| Seq | Timestamp | Type | Name | Duration |
|---|---|---|---|---|
| 0/0 | 2026/09/20 20:10 | flow | patch-triage |
1mArgs:null Results: {
"EnableConfigs": [
"DAMON",
"DAMON_SYSFS",
"DAMON_RECLAIM",
"DAMON_LRU_SORT"
],
"FocusSymbols": [
"damos_set_quota_goal_current_value",
"complement_store",
"complement_show",
"damos_new_quota_goal",
"damos_commit_quota_goal",
"damos_commit_quota_goals",
"damos_sysfs_set_quota_scores"
],
"KMSANReasoning": "The patch adds a boolean 'complement' field to DAMON's quota goal structures (struct damos_quota_goal and struct damos_sysfs_quota_goal) and exposes it via sysfs. \n\n1. Allocation \u0026 Initialization: Sysfs quota goal instances are allocated using kzalloc_obj(), which zeroes all fields by default, while kernel quota goal instances created via damos_new_quota_goal() explicitly initialize goal-\u003ecomplement = complement.\n2. User-space Exposure: The sysfs interface exposes this property via sysfs_emit() with formatted string output ('Y' or 'N'), avoiding any raw structure copying or padding leak to userspace (no copy_to_user of structs with padding).\n3. Arithmetic / Control Flow: The arithmetic operations performed on goal-\u003ecurrent_value based on complement do not alter buffer bounds, length calculations, or memory accesses.\n\nBecause no uninitialized memory can be read or leaked, there is no uninitialized memory risk that requires KMSAN. Standard KASAN/sanitizer configurations are sufficient to test these changes.",
"NeedsKMSAN": false,
"Reasoning": "The patch modifies memory management (mm/damon) by adding a 'complement' option to DAMOS quota goals. This introduces new sysfs handlers (complement_store, complement_show) and modifies quota calculation logic in damos_set_quota_goal_current_value(), where arithmetic operations on goal values (e.g. subtracting from 10000 or reset_interval * 1000) could potentially underflow/overflow. The modified code is reachable from userspace via the DAMON sysfs interface in standard virtualized environments.",
"WorthFuzzing": true
} |
| 1/1 | 2026/09/20 20:10 | action | read-patch-diff |
0mArgs:null Results: {
"PatchDiff": "commit b05a7bec58c8cc3b3748c793cdaa49f65c3b7d63\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Sun Sep 20 20:10:10 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon\nindex 55df688ea596f..4acb2015c2f4f 100644\n--- a/Documentation/ABI/testing/sysfs-kernel-mm-damon\n+++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon\n@@ -375,6 +375,12 @@ Contact:\tSJ Park \u003csj@kernel.org\u003e\n Description:\tWriting to and reading from this file sets and gets the quota\n \t\tauto-tuning goal metric.\n \n+What:\t\t/sys/kernel/mm/damon/admin/kdamonds/\u003cK\u003e/contexts/\u003cC\u003e/schemes/\u003cS\u003e/quotas/goals/\u003cG\u003e/complement\n+Date:\t\tSep 2026\n+Contact:\tSJ Park \u003csj@kernel.org\u003e\n+Description:\tWriting to and reading from this file sets and gets whether to\n+\t\tuse the complement value of the quota auto-tuning goal metric.\n+\n What:\t\t/sys/kernel/mm/damon/admin/kdamonds/\u003cK\u003e/contexts/\u003cC\u003e/schemes/\u003cS\u003e/quotas/goals/\u003cG\u003e/target_value\n Date:\t\tNov 2023\n Contact:\tSJ Park \u003csj@kernel.org\u003e\ndiff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst\nindex ba47255448564..b3f2e591fb7e4 100644\n--- a/Documentation/admin-guide/mm/damon/usage.rst\n+++ b/Documentation/admin-guide/mm/damon/usage.rst\n@@ -98,7 +98,8 @@ comma (\",\").\n │ │ │ │ │ │ │ fail_charge_num,fail_charge_denom\n │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil\n │ │ │ │ │ │ │ │ :ref:`goals \u003csysfs_schemes_quota_goals\u003e`/nr_goals\n- │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value,nid,path\n+ │ │ │ │ │ │ │ │ │ 0/target_metric,complement,target_value,\n+ │ │ │ │ │ │ │ │ │ current_value,nid,path\n │ │ │ │ │ │ │ :ref:`watermarks \u003csysfs_watermarks\u003e`/metric,interval_us,high,mid,low\n │ │ │ │ │ │ │ :ref:`{core_,ops_,}filters \u003csysfs_filters\u003e`/nr_filters\n │ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,damon_target_idx,min,max\n@@ -493,11 +494,11 @@ to ``N-1``. Each directory represents each goal and current achievement.\n Among the multiple feedback, the best one is used.\n \n Each goal directory contains five files, namely ``target_metric``,\n-``target_value``, ``current_value``, ``nid``, and ``path``. Users can set and\n-get the five parameters for the quota auto-tuning goals that specified on the\n-:ref:`design doc \u003cdamon_design_damos_quotas_auto_tuning\u003e` by writing to and\n-reading from each of the files. Because the kernel does not update\n-``current_value``, reading it only makes sense when ``target_metric`` is\n+``complement``, ``target_value``, ``current_value``, ``nid``, and ``path``.\n+Users can set and get the six parameters for the quota auto-tuning goals that\n+specified on the :ref:`design doc \u003cdamon_design_damos_quotas_auto_tuning\u003e` by\n+writing to and reading from each of the files. Because the kernel does not\n+update ``current_value``, reading it only makes sense when ``target_metric`` is\n ``user_input``. Note that users should further write\n ``commit_schemes_quota_goals`` to the ``state`` file of the :ref:`kdamond\n directory \u003csysfs_kdamond\u003e` to pass the feedback to DAMON.\ndiff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst\nindex e82390e77a70a..c82be80738c45 100644\n--- a/Documentation/mm/damon/design.rst\n+++ b/Documentation/mm/damon/design.rst\n@@ -702,10 +702,10 @@ There are two such tuning algorithms that users can select as they need.\n that the zero quota is a valid quota, and therefore ``qt_exceeds`` :ref:`stat\n \u003cdamon_design_damos_stat\u003e` will keep increasing in this case.\n \n-The goal can be specified with five parameters, namely ``target_metric``,\n-``target_value``, ``current_value``, ``nid`` and ``path``. The auto-tuning\n-mechanism tries to make ``current_value`` of ``target_metric`` be same to\n-``target_value``.\n+The goal can be specified with six parameters, namely ``target_metric``,\n+``complement``, ``target_value``, ``current_value``, ``nid`` and ``path``. The\n+auto-tuning mechanism tries to make ``current_value`` of ``complement``-ed\n+``target_metric`` be same to ``target_value``.\n \n - ``user_input``: User-provided value. Users could use any metric that they\n has interest in for the value. Use space main workload's latency or\n@@ -733,6 +733,11 @@ mechanism tries to make ``current_value`` of ``target_metric`` be same to\n - ``hugepage_mem_bp``: Total huge page to total used memory ratio in bp\n (1/10,000).\n \n+``complement`` is a boolean parameter that determines whether to use\n+complemented value of the target metric. For example, if ``complement`` is set\n+and target metric is ``active_mem_bp``, it is effectively same to\n+``inactive_mem_bp``.\n+\n ``nid`` is optionally required for ``node_mem_used_bp``, ``node_mem_free_bp``,\n ``node_memcg_used_bp``, ``node_memcg_free_bp`` and ``node_eligible_mem_bp`` to\n point the specific NUMA node.\ndiff --git a/include/linux/damon.h b/include/linux/damon.h\nindex 836353c4ab9aa..754752d891ca2 100644\n--- a/include/linux/damon.h\n+++ b/include/linux/damon.h\n@@ -175,6 +175,7 @@ enum damos_quota_goal_metric {\n /**\n * struct damos_quota_goal - DAMOS scheme quota auto-tuning goal.\n * @metric:\t\tMetric to be used for representing the goal.\n+ * @complement:\t\tUse the complement of the metric.\n * @target_value:\tTarget value of @metric to achieve with the tuning.\n * @current_value:\tCurrent value of @metric.\n * @nid:\t\tNode id.\n@@ -197,6 +198,7 @@ enum damos_quota_goal_metric {\n */\n struct damos_quota_goal {\n \tenum damos_quota_goal_metric metric;\n+\tbool complement;\n \tunsigned long target_value;\n \tunsigned long current_value;\n \t/* metric-dependent fields */\n@@ -1095,7 +1097,7 @@ bool damos_filter_for_ops(enum damos_filter_type type);\n void damos_destroy_filter(struct damos_filter *f);\n \n struct damos_quota_goal *damos_new_quota_goal(\n-\t\tenum damos_quota_goal_metric metric,\n+\t\tenum damos_quota_goal_metric metric, bool complement,\n \t\tunsigned long target_value);\n void damos_add_quota_goal(struct damos_quota *q, struct damos_quota_goal *g);\n void damos_destroy_quota_goal(struct damos_quota_goal *goal);\ndiff --git a/mm/damon/core.c b/mm/damon/core.c\nindex 2258b72da7a78..2dc1ee96814d0 100644\n--- a/mm/damon/core.c\n+++ b/mm/damon/core.c\n@@ -691,7 +691,7 @@ void damos_destroy_filter(struct damos_filter *f)\n }\n \n struct damos_quota_goal *damos_new_quota_goal(\n-\t\tenum damos_quota_goal_metric metric,\n+\t\tenum damos_quota_goal_metric metric, bool complement,\n \t\tunsigned long target_value)\n {\n \tstruct damos_quota_goal *goal;\n@@ -700,6 +700,7 @@ struct damos_quota_goal *damos_new_quota_goal(\n \tif (!goal)\n \t\treturn NULL;\n \tgoal-\u003emetric = metric;\n+\tgoal-\u003ecomplement = complement;\n \tgoal-\u003etarget_value = target_value;\n \tif (metric == DAMOS_QUOTA_SOME_MEM_PSI_US)\n \t\tgoal-\u003elast_psi_total = U64_MAX;\n@@ -1224,6 +1225,7 @@ static int damos_commit_quota_goal(\n \tif (!src-\u003etarget_value)\n \t\treturn -EINVAL;\n \tdst-\u003emetric = src-\u003emetric;\n+\tdst-\u003ecomplement = src-\u003ecomplement;\n \tdst-\u003etarget_value = src-\u003etarget_value;\n \tif (dst-\u003emetric == DAMOS_QUOTA_USER_INPUT)\n \t\tdst-\u003ecurrent_value = src-\u003ecurrent_value;\n@@ -1261,8 +1263,8 @@ int damos_commit_quota_goals(struct damos_quota *dst, struct damos_quota *src)\n \tdamos_for_each_quota_goal_safe(src_goal, next, src) {\n \t\tif (j++ \u003c i)\n \t\t\tcontinue;\n-\t\tnew_goal = damos_new_quota_goal(\n-\t\t\t\tsrc_goal-\u003emetric, src_goal-\u003etarget_value);\n+\t\tnew_goal = damos_new_quota_goal(src_goal-\u003emetric, false,\n+\t\t\t\tsrc_goal-\u003etarget_value);\n \t\tif (!new_goal)\n \t\t\treturn -ENOMEM;\n \t\terr = damos_commit_quota_goal(new_goal, src_goal);\n@@ -3238,6 +3240,19 @@ static void damos_set_quota_goal_current_value(struct damon_ctx *c,\n \tdefault:\n \t\tbreak;\n \t}\n+\tif (!goal-\u003ecomplement)\n+\t\treturn;\n+\n+\t/* updte current_value to complemented value */\n+\n+\t/* for user_input, users set complemented value on their own */\n+\tif (goal-\u003emetric == DAMOS_QUOTA_USER_INPUT)\n+\t\treturn;\n+\tif (goal-\u003emetric == DAMOS_QUOTA_SOME_MEM_PSI_US)\n+\t\tgoal-\u003ecurrent_value = s-\u003equota.reset_interval * 1000 -\n+\t\t\tgoal-\u003ecurrent_value;\n+\telse\n+\t\tgoal-\u003ecurrent_value = 10000 - goal-\u003ecurrent_value;\n }\n \n /* Return the highest score since it makes schemes least aggressive */\ndiff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c\nindex ad8e86dd3a93e..aca90b8115b8d 100644\n--- a/mm/damon/lru_sort.c\n+++ b/mm/damon/lru_sort.c\n@@ -233,12 +233,13 @@ static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,\n \n \tif (!active_mem_bp)\n \t\treturn 0;\n-\tgoal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, active_mem_bp);\n+\tgoal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, false,\n+\t\t\tactive_mem_bp);\n \tif (!goal)\n \t\treturn -ENOMEM;\n \tdamos_add_quota_goal(\u0026hot_scheme-\u003equota, goal);\n \t/* aim 0.2 % goal conflict, to keep little ping pong */\n-\tgoal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP,\n+\tgoal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP, false,\n \t\t\t10000 - active_mem_bp + 2);\n \tif (!goal)\n \t\treturn -ENOMEM;\ndiff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c\nindex 42a2c9cb13431..014b0779ea6dd 100644\n--- a/mm/damon/reclaim.c\n+++ b/mm/damon/reclaim.c\n@@ -233,7 +233,7 @@ static int damon_reclaim_apply_parameters(void)\n \tdamon_set_schemes(param_ctx, \u0026scheme, 1);\n \n \tif (quota_mem_pressure_us) {\n-\t\tgoal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US,\n+\t\tgoal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US, false,\n \t\t\t\tquota_mem_pressure_us);\n \t\tif (!goal)\n \t\t\tgoto out;\n@@ -241,7 +241,8 @@ static int damon_reclaim_apply_parameters(void)\n \t}\n \n \tif (quota_autotune_feedback) {\n-\t\tgoal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000);\n+\t\tgoal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, false,\n+\t\t\t\t10000);\n \t\tif (!goal)\n \t\t\tgoto out;\n \t\tgoal-\u003ecurrent_value = quota_autotune_feedback;\ndiff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c\nindex bfb6f0bc3f213..8f083611741fd 100644\n--- a/mm/damon/sysfs-schemes.c\n+++ b/mm/damon/sysfs-schemes.c\n@@ -1220,6 +1220,7 @@ static const struct kobj_type damon_sysfs_watermarks_ktype = {\n struct damos_sysfs_quota_goal {\n \tstruct kobject kobj;\n \tenum damos_quota_goal_metric metric;\n+\tbool complement;\n \tunsigned long target_value;\n \tunsigned long current_value;\n \tint nid;\n@@ -1316,6 +1317,30 @@ static ssize_t target_metric_store(struct kobject *kobj,\n \treturn -EINVAL;\n }\n \n+static ssize_t complement_show(struct kobject *kobj,\n+\t\tstruct kobj_attribute *attr, char *buf)\n+{\n+\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\n+\t\t\tstruct damos_sysfs_quota_goal, kobj);\n+\n+\treturn sysfs_emit(buf, \"%c\\n\", goal-\u003ecomplement ? 'Y' : 'N');\n+}\n+\n+static ssize_t complement_store(struct kobject *kobj,\n+\t\tstruct kobj_attribute *attr, const char *buf, size_t count)\n+{\n+\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\n+\t\t\tstruct damos_sysfs_quota_goal, kobj);\n+\tbool complement;\n+\tint err = kstrtobool(buf, \u0026complement);\n+\n+\tif (err)\n+\t\treturn err;\n+\n+\tgoal-\u003ecomplement = complement;\n+\treturn count;\n+}\n+\n static ssize_t target_value_show(struct kobject *kobj,\n \t\tstruct kobj_attribute *attr, char *buf)\n {\n@@ -1424,6 +1449,9 @@ static void damos_sysfs_quota_goal_release(struct kobject *kobj)\n static struct kobj_attribute damos_sysfs_quota_goal_target_metric_attr =\n \t\t__ATTR_RW_MODE(target_metric, 0600);\n \n+static struct kobj_attribute damos_sysfs_quota_goal_complement_attr =\n+\t\t__ATTR_RW_MODE(complement, 0600);\n+\n static struct kobj_attribute damos_sysfs_quota_goal_target_value_attr =\n \t\t__ATTR_RW_MODE(target_value, 0600);\n \n@@ -1438,6 +1466,7 @@ static struct kobj_attribute damos_sysfs_quota_goal_path_attr =\n \n static struct attribute *damos_sysfs_quota_goal_attrs[] = {\n \t\u0026damos_sysfs_quota_goal_target_metric_attr.attr,\n+\t\u0026damos_sysfs_quota_goal_complement_attr.attr,\n \t\u0026damos_sysfs_quota_goal_target_value_attr.attr,\n \t\u0026damos_sysfs_quota_goal_current_value_attr.attr,\n \t\u0026damos_sysfs_quota_goal_nid_attr.attr,\n@@ -2870,6 +2899,7 @@ static int damos_sysfs_add_quota_score(\n \t\t\tcontinue;\n \n \t\tgoal = damos_new_quota_goal(sysfs_goal-\u003emetric,\n+\t\t\t\tsysfs_goal-\u003ecomplement,\n \t\t\t\tsysfs_goal-\u003etarget_value);\n \t\tif (!goal)\n \t\t\treturn -ENOMEM;\ndiff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h\nindex 5ff0436c58441..2394e074ef628 100644\n--- a/mm/damon/tests/core-kunit.h\n+++ b/mm/damon/tests/core-kunit.h\n@@ -819,6 +819,7 @@ static void damos_test_commit_quota_goal_for(struct kunit *test,\n \tdamos_commit_quota_goal(dst, src);\n \n \tKUNIT_EXPECT_EQ(test, dst-\u003emetric, src-\u003emetric);\n+\tKUNIT_EXPECT_EQ(test, dst-\u003ecomplement, src-\u003ecomplement);\n \tKUNIT_EXPECT_EQ(test, dst-\u003etarget_value, src-\u003etarget_value);\n \tif (src-\u003emetric == DAMOS_QUOTA_USER_INPUT)\n \t\tKUNIT_EXPECT_EQ(test, dst-\u003ecurrent_value, src-\u003ecurrent_value);\n@@ -862,6 +863,7 @@ static void damos_test_commit_quota_goal(struct kunit *test)\n \tdamos_test_commit_quota_goal_for(test, \u0026dst,\n \t\t\t\u0026(struct damos_quota_goal){\n \t\t\t.metric = DAMOS_QUOTA_USER_INPUT,\n+\t\t\t.complement = true,\n \t\t\t.target_value = 789,\n \t\t\t.current_value = 12});\n \tdamos_test_commit_quota_goal_for(test, \u0026dst,\n@@ -929,7 +931,7 @@ static void damos_test_commit_quota_goals_for(struct kunit *test,\n \t\t * damos_commit_quota_goals() will kfree() the dst goals.\n \t\t * Make it kfree()-able.\n \t\t */\n-\t\tgoal = damos_new_quota_goal(dst_goals[i].metric,\n+\t\tgoal = damos_new_quota_goal(dst_goals[i].metric, false,\n \t\t\t\tdst_goals[i].target_value);\n \t\tif (!goal)\n \t\t\tgoto out;\ndiff --git a/samples/damon/mtier.c b/samples/damon/mtier.c\nindex 27dc88bdf7a0e..a2e311082cd4b 100644\n--- a/samples/damon/mtier.c\n+++ b/samples/damon/mtier.c\n@@ -163,7 +163,7 @@ static struct damon_ctx *damon_sample_mtier_build_ctx(bool promote)\n \tdamon_set_schemes(ctx, \u0026scheme, 1);\n \tquota_goal = damos_new_quota_goal(\n \t\t\tpromote ? DAMOS_QUOTA_NODE_MEM_USED_BP :\n-\t\t\tDAMOS_QUOTA_NODE_MEM_FREE_BP,\n+\t\t\tDAMOS_QUOTA_NODE_MEM_FREE_BP, false,\n \t\t\tpromote ? node0_mem_used_bp : node0_mem_free_bp);\n \tif (!quota_goal)\n \t\tgoto free_out;\n"
} |
| 2/1 | 2026/09/20 20:10 | agent | patch-evaluator |
0mModel:core Args: null Results: {
"EnableConfigs": [
"DAMON",
"DAMON_SYSFS",
"DAMON_RECLAIM",
"DAMON_LRU_SORT"
],
"FocusSymbols": [
"damos_set_quota_goal_current_value",
"complement_store",
"complement_show",
"damos_new_quota_goal",
"damos_commit_quota_goal",
"damos_commit_quota_goals",
"damos_sysfs_set_quota_scores"
],
"Reasoning": "The patch modifies memory management (mm/damon) by adding a 'complement' option to DAMOS quota goals. This introduces new sysfs handlers (complement_store, complement_show) and modifies quota calculation logic in damos_set_quota_goal_current_value(), where arithmetic operations on goal values (e.g. subtracting from 10000 or reset_interval * 1000) could potentially underflow/overflow. The modified code is reachable from userspace via the DAMON sysfs interface in standard virtualized environments.",
"WorthFuzzing": true
}Instruction: You are an expert Linux kernel maintainer and security engineer.
Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller.
IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on internal assumptions. You must actively use your code access
tools to inspect the actual source code, callers, and surrounding context.
================================================================================
1. CORE TRIAGE PHILOSOPHY
================================================================================
The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs,
and newly triggered assertions introduced by the patch series.
- REACHABILITY IS THE PRIMARY GATE:
Fuzzing can only discover bugs in code that can actually execute in standard virtualized
environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap).
If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed,
regardless of whether it adds assertions or complex logic.
- DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS:
Patch authors routinely label changes as "cleanups", "refactorings", or state
"No functional change intended". Do NOT take these claims at face value.
Code refactorings that rearrange logic, introduce helper functions, or alter state management
in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs.
If reachable executable code is modified or refactored, it MUST be fuzzed.
- NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED:
When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON*, VM_WARN_ON*,
BUG_ON*, lockdep_assert*) in reachable code paths, it enforces new or stricter invariants.
Even if the author believes the invariant always holds, fuzzing is essential to verify whether
an unusual sequence of operations can violate it.
================================================================================
2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA)
================================================================================
Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories:
- Non-kernel and non-executable changes:
* Modifications to Documentation/, comments, or spelling fixes.
* User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/)
that do not affect the compiled kernel image (vmlinux) or kernel modules.
* Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints
that do not alter control flow or data structures.
* Build system or Kconfig changes that do not alter compiled C logic.
- Structurally unreachable hardware:
* Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed,
ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU.
- Unreachable execution paths:
* Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during
physical PCI hot-unplug or manual sysfs driver unbinding.
* Code paths exclusive to architectures other than the target architecture.
================================================================================
3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA)
================================================================================
Return WorthFuzzing=true whenever the patch touches reachable executable code, including:
- Core Subsystems:
* Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/),
BPF, scheduler, core networking, VFS, or syscall handling.
- Refactorings and Code Cleanups:
* Any restructuring of reachable data structures, helper abstractions, or algorithm flows.
- Runtime Assertions and Defensive Checks:
* Any introduction or alteration of assertions (WARN_ON*, VM_WARN_ON*, BUG_ON*, etc.) in reachable paths.
- Reachable Drivers and Protocols:
* Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.).
================================================================================
4. EXTRACTING FocusSymbols (PREVENTING DILUTION)
================================================================================
When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer:
- AVOID UBIQUITOUS LIFECYCLE HOT-PATHS:
Do NOT list generic, ubiquitous functions called by almost every program in the corpus
(including, but not limited to: general memory allocators and deallocators, page fault
and trap handlers, or core synchronization primitives; this is not an exhaustive list).
Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused",
which severely dilutes fuzzing effort away from the actual changes.
- TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS:
List functions that specifically implement the logic being added or altered, or direct API entrypoints
for the subsystem feature under review.
- HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h):
Compiler-inlined static functions (such as static inlines in mm/*.h or include/linux/*.h) lack
distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters.
If the changes are primarily in static inline helpers, identify non-static, feature-specific caller
functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers).
================================================================================
5. IDENTIFYING EnableConfigs
================================================================================
Identify any specific CONFIG_ options required to properly compile and reach the modified code:
- Inspect Kconfig files and #ifdef guards; do not make assumptions.
- Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed.
- Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit b05a7bec58c8cc3b3748c793cdaa49f65c3b7d63
Author: syz-cluster <triage@syzkaller.com>
Date: Sun Sep 20 20:10:10 2026 +0000
syz-cluster: applied patch under review
diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
index 55df688ea596f..4acb2015c2f4f 100644
--- a/Documentation/ABI/testing/sysfs-kernel-mm-damon
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
@@ -375,6 +375,12 @@ Contact: SJ Park <sj@kernel.org>
Description: Writing to and reading from this file sets and gets the quota
auto-tuning goal metric.
+What: /sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/goals/<G>/complement
+Date: Sep 2026
+Contact: SJ Park <sj@kernel.org>
+Description: Writing to and reading from this file sets and gets whether to
+ use the complement value of the quota auto-tuning goal metric.
+
What: /sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/goals/<G>/target_value
Date: Nov 2023
Contact: SJ Park <sj@kernel.org>
diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index ba47255448564..b3f2e591fb7e4 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -98,7 +98,8 @@ comma (",").
│ │ │ │ │ │ │ fail_charge_num,fail_charge_denom
│ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil
│ │ │ │ │ │ │ │ :ref:`goals <sysfs_schemes_quota_goals>`/nr_goals
- │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value,nid,path
+ │ │ │ │ │ │ │ │ │ 0/target_metric,complement,target_value,
+ │ │ │ │ │ │ │ │ │ current_value,nid,path
│ │ │ │ │ │ │ :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low
│ │ │ │ │ │ │ :ref:`{core_,ops_,}filters <sysfs_filters>`/nr_filters
│ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,damon_target_idx,min,max
@@ -493,11 +494,11 @@ to ``N-1``. Each directory represents each goal and current achievement.
Among the multiple feedback, the best one is used.
Each goal directory contains five files, namely ``target_metric``,
-``target_value``, ``current_value``, ``nid``, and ``path``. Users can set and
-get the five parameters for the quota auto-tuning goals that specified on the
-:ref:`design doc <damon_design_damos_quotas_auto_tuning>` by writing to and
-reading from each of the files. Because the kernel does not update
-``current_value``, reading it only makes sense when ``target_metric`` is
+``complement``, ``target_value``, ``current_value``, ``nid``, and ``path``.
+Users can set and get the six parameters for the quota auto-tuning goals that
+specified on the :ref:`design doc <damon_design_damos_quotas_auto_tuning>` by
+writing to and reading from each of the files. Because the kernel does not
+update ``current_value``, reading it only makes sense when ``target_metric`` is
``user_input``. Note that users should further write
``commit_schemes_quota_goals`` to the ``state`` file of the :ref:`kdamond
directory <sysfs_kdamond>` to pass the feedback to DAMON.
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index e82390e77a70a..c82be80738c45 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -702,10 +702,10 @@ There are two such tuning algorithms that users can select as they need.
that the zero quota is a valid quota, and therefore ``qt_exceeds`` :ref:`stat
<damon_design_damos_stat>` will keep increasing in this case.
-The goal can be specified with five parameters, namely ``target_metric``,
-``target_value``, ``current_value``, ``nid`` and ``path``. The auto-tuning
-mechanism tries to make ``current_value`` of ``target_metric`` be same to
-``target_value``.
+The goal can be specified with six parameters, namely ``target_metric``,
+``complement``, ``target_value``, ``current_value``, ``nid`` and ``path``. The
+auto-tuning mechanism tries to make ``current_value`` of ``complement``-ed
+``target_metric`` be same to ``target_value``.
- ``user_input``: User-provided value. Users could use any metric that they
has interest in for the value. Use space main workload's latency or
@@ -733,6 +733,11 @@ mechanism tries to make ``current_value`` of ``target_metric`` be same to
- ``hugepage_mem_bp``: Total huge page to total used memory ratio in bp
(1/10,000).
+``complement`` is a boolean parameter that determines whether to use
+complemented value of the target metric. For example, if ``complement`` is set
+and target metric is ``active_mem_bp``, it is effectively same to
+``inactive_mem_bp``.
+
``nid`` is optionally required for ``node_mem_used_bp``, ``node_mem_free_bp``,
``node_memcg_used_bp``, ``node_memcg_free_bp`` and ``node_eligible_mem_bp`` to
point the specific NUMA node.
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 836353c4ab9aa..754752d891ca2 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -175,6 +175,7 @@ enum damos_quota_goal_metric {
/**
* struct damos_quota_goal - DAMOS scheme quota auto-tuning goal.
* @metric: Metric to be used for representing the goal.
+ * @complement: Use the complement of the metric.
* @target_value: Target value of @metric to achieve with the tuning.
* @current_value: Current value of @metric.
* @nid: Node id.
@@ -197,6 +198,7 @@ enum damos_quota_goal_metric {
*/
struct damos_quota_goal {
enum damos_quota_goal_metric metric;
+ bool complement;
unsigned long target_value;
unsigned long current_value;
/* metric-dependent fields */
@@ -1095,7 +1097,7 @@ bool damos_filter_for_ops(enum damos_filter_type type);
void damos_destroy_filter(struct damos_filter *f);
struct damos_quota_goal *damos_new_quota_goal(
- enum damos_quota_goal_metric metric,
+ enum damos_quota_goal_metric metric, bool complement,
unsigned long target_value);
void damos_add_quota_goal(struct damos_quota *q, struct damos_quota_goal *g);
void damos_destroy_quota_goal(struct damos_quota_goal *goal);
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 2258b72da7a78..2dc1ee96814d0 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -691,7 +691,7 @@ void damos_destroy_filter(struct damos_filter *f)
}
struct damos_quota_goal *damos_new_quota_goal(
- enum damos_quota_goal_metric metric,
+ enum damos_quota_goal_metric metric, bool complement,
unsigned long target_value)
{
struct damos_quota_goal *goal;
@@ -700,6 +700,7 @@ struct damos_quota_goal *damos_new_quota_goal(
if (!goal)
return NULL;
goal->metric = metric;
+ goal->complement = complement;
goal->target_value = target_value;
if (metric == DAMOS_QUOTA_SOME_MEM_PSI_US)
goal->last_psi_total = U64_MAX;
@@ -1224,6 +1225,7 @@ static int damos_commit_quota_goal(
if (!src->target_value)
return -EINVAL;
dst->metric = src->metric;
+ dst->complement = src->complement;
dst->target_value = src->target_value;
if (dst->metric == DAMOS_QUOTA_USER_INPUT)
dst->current_value = src->current_value;
@@ -1261,8 +1263,8 @@ int damos_commit_quota_goals(struct damos_quota *dst, struct damos_quota *src)
damos_for_each_quota_goal_safe(src_goal, next, src) {
if (j++ < i)
continue;
- new_goal = damos_new_quota_goal(
- src_goal->metric, src_goal->target_value);
+ new_goal = damos_new_quota_goal(src_goal->metric, false,
+ src_goal->target_value);
if (!new_goal)
return -ENOMEM;
err = damos_commit_quota_goal(new_goal, src_goal);
@@ -3238,6 +3240,19 @@ static void damos_set_quota_goal_current_value(struct damon_ctx *c,
default:
break;
}
+ if (!goal->complement)
+ return;
+
+ /* updte current_value to complemented value */
+
+ /* for user_input, users set complemented value on their own */
+ if (goal->metric == DAMOS_QUOTA_USER_INPUT)
+ return;
+ if (goal->metric == DAMOS_QUOTA_SOME_MEM_PSI_US)
+ goal->current_value = s->quota.reset_interval * 1000 -
+ goal->current_value;
+ else
+ goal->current_value = 10000 - goal->current_value;
}
/* Return the highest score since it makes schemes least aggressive */
diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index ad8e86dd3a93e..aca90b8115b8d 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -233,12 +233,13 @@ static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,
if (!active_mem_bp)
return 0;
- goal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, active_mem_bp);
+ goal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, false,
+ active_mem_bp);
if (!goal)
return -ENOMEM;
damos_add_quota_goal(&hot_scheme->quota, goal);
/* aim 0.2 % goal conflict, to keep little ping pong */
- goal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP,
+ goal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP, false,
10000 - active_mem_bp + 2);
if (!goal)
return -ENOMEM;
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index 42a2c9cb13431..014b0779ea6dd 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -233,7 +233,7 @@ static int damon_reclaim_apply_parameters(void)
damon_set_schemes(param_ctx, &scheme, 1);
if (quota_mem_pressure_us) {
- goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US,
+ goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US, false,
quota_mem_pressure_us);
if (!goal)
goto out;
@@ -241,7 +241,8 @@ static int damon_reclaim_apply_parameters(void)
}
if (quota_autotune_feedback) {
- goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000);
+ goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, false,
+ 10000);
if (!goal)
goto out;
goal->current_value = quota_autotune_feedback;
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index bfb6f0bc3f213..8f083611741fd 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1220,6 +1220,7 @@ static const struct kobj_type damon_sysfs_watermarks_ktype = {
struct damos_sysfs_quota_goal {
struct kobject kobj;
enum damos_quota_goal_metric metric;
+ bool complement;
unsigned long target_value;
unsigned long current_value;
int nid;
@@ -1316,6 +1317,30 @@ static ssize_t target_metric_store(struct kobject *kobj,
return -EINVAL;
}
+static ssize_t complement_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct damos_sysfs_quota_goal *goal = container_of(kobj,
+ struct damos_sysfs_quota_goal, kobj);
+
+ return sysfs_emit(buf, "%c\n", goal->complement ? 'Y' : 'N');
+}
+
+static ssize_t complement_store(struct kobject *kobj,
+ struct kobj_attribute *attr, const char *buf, size_t count)
+{
+ struct damos_sysfs_quota_goal *goal = container_of(kobj,
+ struct damos_sysfs_quota_goal, kobj);
+ bool complement;
+ int err = kstrtobool(buf, &complement);
+
+ if (err)
+ return err;
+
+ goal->complement = complement;
+ return count;
+}
+
static ssize_t target_value_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -1424,6 +1449,9 @@ static void damos_sysfs_quota_goal_release(struct kobject *kobj)
static struct kobj_attribute damos_sysfs_quota_goal_target_metric_attr =
__ATTR_RW_MODE(target_metric, 0600);
+static struct kobj_attribute damos_sysfs_quota_goal_complement_attr =
+ __ATTR_RW_MODE(complement, 0600);
+
static struct kobj_attribute damos_sysfs_quota_goal_target_value_attr =
__ATTR_RW_MODE(target_value, 0600);
@@ -1438,6 +1466,7 @@ static struct kobj_attribute damos_sysfs_quota_goal_path_attr =
static struct attribute *damos_sysfs_quota_goal_attrs[] = {
&damos_sysfs_quota_goal_target_metric_attr.attr,
+ &damos_sysfs_quota_goal_complement_attr.attr,
&damos_sysfs_quota_goal_target_value_attr.attr,
&damos_sysfs_quota_goal_current_value_attr.attr,
&damos_sysfs_quota_goal_nid_attr.attr,
@@ -2870,6 +2899,7 @@ static int damos_sysfs_add_quota_score(
continue;
goal = damos_new_quota_goal(sysfs_goal->metric,
+ sysfs_goal->complement,
sysfs_goal->target_value);
if (!goal)
return -ENOMEM;
diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 5ff0436c58441..2394e074ef628 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -819,6 +819,7 @@ static void damos_test_commit_quota_goal_for(struct kunit *test,
damos_commit_quota_goal(dst, src);
KUNIT_EXPECT_EQ(test, dst->metric, src->metric);
+ KUNIT_EXPECT_EQ(test, dst->complement, src->complement);
KUNIT_EXPECT_EQ(test, dst->target_value, src->target_value);
if (src->metric == DAMOS_QUOTA_USER_INPUT)
KUNIT_EXPECT_EQ(test, dst->current_value, src->current_value);
@@ -862,6 +863,7 @@ static void damos_test_commit_quota_goal(struct kunit *test)
damos_test_commit_quota_goal_for(test, &dst,
&(struct damos_quota_goal){
.metric = DAMOS_QUOTA_USER_INPUT,
+ .complement = true,
.target_value = 789,
.current_value = 12});
damos_test_commit_quota_goal_for(test, &dst,
@@ -929,7 +931,7 @@ static void damos_test_commit_quota_goals_for(struct kunit *test,
* damos_commit_quota_goals() will kfree() the dst goals.
* Make it kfree()-able.
*/
- goal = damos_new_quota_goal(dst_goals[i].metric,
+ goal = damos_new_quota_goal(dst_goals[i].metric, false,
dst_goals[i].target_value);
if (!goal)
goto out;
diff --git a/samples/damon/mtier.c b/samples/damon/mtier.c
index 27dc88bdf7a0e..a2e311082cd4b 100644
--- a/samples/damon/mtier.c
+++ b/samples/damon/mtier.c
@@ -163,7 +163,7 @@ static struct damon_ctx *damon_sample_mtier_build_ctx(bool promote)
damon_set_schemes(ctx, &scheme, 1);
quota_goal = damos_new_quota_goal(
promote ? DAMOS_QUOTA_NODE_MEM_USED_BP :
- DAMOS_QUOTA_NODE_MEM_FREE_BP,
+ DAMOS_QUOTA_NODE_MEM_FREE_BP, false,
promote ? node0_mem_used_bp : node0_mem_free_bp);
if (!quota_goal)
goto free_out;
|
| 3/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 7995 output: 28 thoughts: 986 Thoughts: **DAMON Patch Analysis: Potential Vulnerability Discovered** Okay, let's break this down. First, I need to understand what this patch is doing. It's touching DAMON, the Data Access Monitor, deep within the memory management subsystem. That's immediately interesting; memory management is a critical area. The patch affects several files, including documentation and code, but specifically these files are notable: * `include/linux/damon.h`: Modifies the `struct damos_quota_goal` by adding a `bool complement`. Also updates `damos_new_quota_goal` prototype to take `bool complement`. * `mm/damon/core.c`: Modifies core functions related to quota goals, including how the `complement` flag is handled and stored. Notably, I've noticed a potentially dangerous flaw. * `mm/damon/sysfs-schemes.c`: Adds sysfs attributes (`complement_show`, `complement_store`) for the `complement` flag, enabling user-space interaction with this new feature. The core of the issue seems to be the introduction of this `complement` flag. In `mm/damon/core.c`, the `damos_set_quota_goal_current_value()` function is where it gets interesting. I see a comment in that code, and I see a potential *integer underflow vulnerability* that might be present. Specifically, the subtraction of `goal->current_value` from a fixed value (either `s->quota.reset_interval * 1000` or `10000`). If `goal->current_value` is larger than the fixed value, the unsigned long underflows, resulting in a large positive number. This could lead to unexpected behavior, potentially bypassing quota limits. This is a critical point that needs thorough analysis. Considering the sysfs exposure in `mm/damon/sysfs-schemes.c` with the `complement` attribute, this is something that a user in root or admin privileges can directly control via the filesystem, which means this flaw may be user-exploitable. Now, from a fuzzing perspective, DAMON is definitely reachable and worth investigating. This is good news, as it gives me the go-ahead. It's part of `mm/`, making it a core subsystem. The user-space sysfs interface makes it *readily* accessible, and completely software-based, I can control and manipulate it from userspace. My next step will be to confirm the Kconfig options for DAMON and the DAMON sysfs interface to see if they're enabled by default, and if so, how to interact with it. I'll need to check if syzkaller can interact with this sysfs interface; it's capable of writing to sysfs, so there's a good chance it can be used to trigger the vulnerability. |
| 4/2 | 2026/09/20 20:10 | tool | grepper |
0mArgs:{
"Expression": "config DAMON",
"PathPrefix": "mm/damon/"
}Results: {
"Output": "mm/damon/Kconfig=3=menu \"Data Access Monitoring\"\nmm/damon/Kconfig-4-\nmm/damon/Kconfig:5:config DAMON\nmm/damon/Kconfig-6-\tbool \"DAMON: Data Access Monitoring Framework\"\n--\nmm/damon/Kconfig-14-\nmm/damon/Kconfig:15:config DAMON_DEBUG_SANITY\nmm/damon/Kconfig-16-\tbool \"Check sanity of DAMON code\"\n--\nmm/damon/Kconfig-25-\nmm/damon/Kconfig:26:config DAMON_KUNIT_TEST\nmm/damon/Kconfig-27-\tbool \"Test for damon\" if !KUNIT_ALL_TESTS\n--\nmm/damon/Kconfig-37-\nmm/damon/Kconfig:38:config DAMON_VADDR\nmm/damon/Kconfig-39-\tbool \"Data access monitoring operations for virtual address spaces\"\n--\nmm/damon/Kconfig-46-\nmm/damon/Kconfig:47:config DAMON_PADDR\nmm/damon/Kconfig-48-\tbool \"Data access monitoring operations for the physical address space\"\n--\nmm/damon/Kconfig-55-\nmm/damon/Kconfig:56:config DAMON_VADDR_KUNIT_TEST\nmm/damon/Kconfig-57-\tbool \"Test for DAMON operations\" if !KUNIT_ALL_TESTS\n--\nmm/damon/Kconfig-67-\nmm/damon/Kconfig:68:config DAMON_SYSFS\nmm/damon/Kconfig-69-\tbool \"DAMON sysfs interface\"\n--\nmm/damon/Kconfig-75-\nmm/damon/Kconfig:76:config DAMON_SYSFS_KUNIT_TEST\nmm/damon/Kconfig-77-\tbool \"Test for damon sysfs interface\" if !KUNIT_ALL_TESTS\n--\nmm/damon/Kconfig-87-\nmm/damon/Kconfig:88:config DAMON_RECLAIM\nmm/damon/Kconfig-89-\tbool \"Build DAMON-based reclaim (DAMON_RECLAIM)\"\n--\nmm/damon/Kconfig-99-\nmm/damon/Kconfig:100:config DAMON_LRU_SORT\nmm/damon/Kconfig-101-\tbool \"Build DAMON-based LRU-lists sorting (DAMON_LRU_SORT)\"\n--\nmm/damon/Kconfig-107-\nmm/damon/Kconfig:108:config DAMON_STAT\nmm/damon/Kconfig-109-\tbool \"Build data access monitoring stat (DAMON_STAT)\"\n--\nmm/damon/Kconfig-115-\nmm/damon/Kconfig:116:config DAMON_STAT_ENABLED_DEFAULT\nmm/damon/Kconfig-117-\tbool \"Enable DAMON_STAT by default\"\n"
} |
| 5/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 10371 output: 33 thoughts: 22 Thoughts: Here's a summary of my immediate thought process: **Diving into DAMON's Makefile and Kconfig** Okay, time to get my hands dirty. I need to take a look at the core build infrastructure for the Data Access Monitor (DAMON) implementation. My first step is to open up `mm/damon/Makefile` and `mm/damon/Kconfig`. I'm expecting to find the standard build rules and likely the module definitions in the Makefile. From a Kconfig perspective, I'll be looking for the configuration options that govern DAMON's features, dependencies, and any runtime behaviors that are controlled through kernel configurations. I'm keen to understand how the build system integrates DAMON and to see the modularity of the design, which might reveal aspects related to its scalability and configurability. Analyzing the Makefile will quickly give me insight into the build process, while Kconfig will illuminate the available configuration choices. This is my starting point for understanding how DAMON is baked into the kernel. |
| 6/2 | 2026/09/20 20:10 | tool | read-file |
0mArgs:{
"File": "mm/damon/Kconfig",
"FirstLine": 1,
"LineCount": 90
}Results: {
"Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\t\n 3:\tmenu \"Data Access Monitoring\"\n 4:\t\n 5:\tconfig DAMON\n 6:\t\tbool \"DAMON: Data Access Monitoring Framework\"\n 7:\t\thelp\n 8:\t\t This builds a framework that allows kernel subsystems to monitor\n 9:\t\t access frequency of each memory region. The information can be useful\n 10:\t\t for performance-centric DRAM level memory management.\n 11:\t\n 12:\t\t See https://www.kernel.org/doc/html/latest/mm/damon/index.html for\n 13:\t\t more information.\n 14:\t\n 15:\tconfig DAMON_DEBUG_SANITY\n 16:\t\tbool \"Check sanity of DAMON code\"\n 17:\t\tdepends on DAMON\n 18:\t\thelp\n 19:\t\t This enables additional DAMON debugging-purpose sanity checks in\n 20:\t\t DAMON code. This can be useful for finding bugs, but impose\n 21:\t\t additional overhead. This is therefore recommended to be enabled on\n 22:\t\t only development and test setups.\n 23:\t\n 24:\t\t If unsure, say N.\n 25:\t\n 26:\tconfig DAMON_KUNIT_TEST\n 27:\t\tbool \"Test for damon\" if !KUNIT_ALL_TESTS\n 28:\t\tdepends on DAMON \u0026\u0026 KUNIT=y\n 29:\t\tdefault KUNIT_ALL_TESTS\n 30:\t\thelp\n 31:\t\t This builds the DAMON Kunit test suite.\n 32:\t\n 33:\t\t For more information on KUnit and unit tests in general, please refer\n 34:\t\t to the KUnit documentation.\n 35:\t\n 36:\t\t If unsure, say N.\n 37:\t\n 38:\tconfig DAMON_VADDR\n 39:\t\tbool \"Data access monitoring operations for virtual address spaces\"\n 40:\t\tdepends on DAMON \u0026\u0026 MMU\n 41:\t\tselect PAGE_IDLE_FLAG\n 42:\t\tdefault DAMON\n 43:\t\thelp\n 44:\t\t This builds the default data access monitoring operations for DAMON\n 45:\t\t that work for virtual address spaces.\n 46:\t\n 47:\tconfig DAMON_PADDR\n 48:\t\tbool \"Data access monitoring operations for the physical address space\"\n 49:\t\tdepends on DAMON \u0026\u0026 MMU\n 50:\t\tselect PAGE_IDLE_FLAG\n 51:\t\tdefault DAMON\n 52:\t\thelp\n 53:\t\t This builds the default data access monitoring operations for DAMON\n 54:\t\t that works for the physical address space.\n 55:\t\n 56:\tconfig DAMON_VADDR_KUNIT_TEST\n 57:\t\tbool \"Test for DAMON operations\" if !KUNIT_ALL_TESTS\n 58:\t\tdepends on DAMON_VADDR \u0026\u0026 KUNIT=y\n 59:\t\tdefault KUNIT_ALL_TESTS\n 60:\t\thelp\n 61:\t\t This builds the DAMON virtual addresses operations Kunit test suite.\n 62:\t\n 63:\t\t For more information on KUnit and unit tests in general, please refer\n 64:\t\t to the KUnit documentation.\n 65:\t\n 66:\t\t If unsure, say N.\n 67:\t\n 68:\tconfig DAMON_SYSFS\n 69:\t\tbool \"DAMON sysfs interface\"\n 70:\t\tdepends on DAMON \u0026\u0026 SYSFS\n 71:\t\tdefault DAMON\n 72:\t\thelp\n 73:\t\t This builds the sysfs interface for DAMON. The user space can use\n 74:\t\t the interface for arbitrary data access monitoring.\n 75:\t\n 76:\tconfig DAMON_SYSFS_KUNIT_TEST\n 77:\t\tbool \"Test for damon sysfs interface\" if !KUNIT_ALL_TESTS\n 78:\t\tdepends on DAMON_SYSFS \u0026\u0026 KUNIT=y\n 79:\t\tdefault KUNIT_ALL_TESTS\n 80:\t\thelp\n 81:\t\t This builds the DAMON sysfs interface Kunit test suite.\n 82:\t\n 83:\t\t For more information on KUnit and unit tests in general, please refer\n 84:\t\t to the KUnit documentation.\n 85:\t\n 86:\t\t If unsure, say N.\n 87:\t\n 88:\tconfig DAMON_RECLAIM\n 89:\t\tbool \"Build DAMON-based reclaim (DAMON_RECLAIM)\"\n 90:\t\tdepends on DAMON_PADDR\n"
} |
| 7/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 11815 output: 32 thoughts: 12 Thoughts: Here's a summary of my thought process, as if I were the one thinking it: **Diving into the Makefile** Alright, time to get my hands dirty. My immediate instinct is to take a look at the `mm/damon/Makefile`. This is where the core build instructions for the DAMON subsystem should reside, and it's the logical starting point for understanding how this part of the memory management code is structured and compiled. I'll be looking for things like include paths, compilation flags, object file dependencies, and how DAMON modules might be linked together. Hopefully, it's well-organized and clearly documents the build process. Knowing the Makefile will be crucial for any in-depth investigation or modification of the DAMON implementation. Let's see what's in there! |
| 8/2 | 2026/09/20 20:10 | tool | read-file |
0mArgs:{
"File": "mm/damon/Makefile",
"FirstLine": 1,
"LineCount": 20
}Results: {
"Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0\n 2:\t\n 3:\tobj-y\t\t\t\t:= core.o\n 4:\tobj-$(CONFIG_DAMON_VADDR)\t+= ops-common.o vaddr.o\n 5:\tobj-$(CONFIG_DAMON_PADDR)\t+= ops-common.o paddr.o\n 6:\tobj-$(CONFIG_DAMON_SYSFS)\t+= sysfs-common.o sysfs-schemes.o sysfs.o\n 7:\tobj-$(CONFIG_DAMON_RECLAIM)\t+= modules-common.o reclaim.o\n 8:\tobj-$(CONFIG_DAMON_LRU_SORT)\t+= modules-common.o lru_sort.o\n 9:\tobj-$(CONFIG_DAMON_STAT)\t+= modules-common.o stat.o\n"
} |
| 9/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 12245 output: 25 thoughts: 63 Thoughts: **Investigating the DAMON Configuration** Okay, so I'm looking at this `mm/damon/Makefile`, and it's pretty straightforward: if `CONFIG_DAMON` is enabled, then `core.o` gets built within the `mm/damon` directory. Standard stuff. But wait a minute...how exactly is this `mm/damon` directory getting integrated into the overall `mm/` build process? Where's the connection point? I need to track down how `mm/damon` is included within the main `mm/Makefile`. Time to go spelunking in the parent `Makefile` to see how this all fits together. This feels like it should be documented... |
| 10/2 | 2026/09/20 20:10 | tool | grepper |
0mArgs:{
"Expression": "damon",
"PathPrefix": "mm/Makefile"
}Results: {
"Output": "mm/Makefile=136=obj-$(CONFIG_DEBUG_PAGE_REF) += debug_page_ref.o\nmm/Makefile:137:obj-$(CONFIG_DAMON) += damon/\nmm/Makefile-138-obj-$(CONFIG_HARDENED_USERCOPY) += usercopy.o\n"
} |
| 11/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 12570 output: 37 thoughts: 160 Thoughts: **My Assessment of the DAMON Configuration and Quota Goal Mechanism** Okay, let's break this down. The configuration options for DAMON are pretty modular, which is good to see. `CONFIG_DAMON` itself is the base, responsible for building `mm/damon/core.o` – the core functionality. Then we have a few add-ons: `CONFIG_DAMON_SYSFS` builds the sysfs interface components, which depend on the base DAMON and the `SYSFS` infrastructure, specifically generating `sysfs-schemes.o`, `sysfs.o`, and `sysfs-common.o`. `CONFIG_DAMON_PADDR` adds physical address mapping, constructing `paddr.o`. This physical address support then unlocks more specialized features like `CONFIG_DAMON_RECLAIM` and `CONFIG_DAMON_LRU_SORT`, which build `reclaim.o` and `lru_sort.o` respectively and rely on `DAMON_PADDR`. Now, I need to understand how the quota goals are actually *used* in this framework. My next step is to trace how `damos_set_quota_goal_current_value` is called. It will give me the insights I need to see how the quota system influences DAMON's behavior and the interaction with its internals. I'm keen to examine the call sites and context to understand the trigger conditions for these adjustments. |
| 12/2 | 2026/09/20 20:10 | tool | grepper |
0mArgs:{
"Expression": "damos_set_quota_goal_current_value",
"PathPrefix": "mm/damon/"
}Results: {
"Output": "mm/damon/core.c=3185=static unsigned int damos_hugepage_mem_bp(void)\n--\nmm/damon/core.c-3200-\nmm/damon/core.c:3201:static void damos_set_quota_goal_current_value(struct damon_ctx *c,\nmm/damon/core.c-3202-\t\tstruct damos *s, struct damos_quota_goal *goal)\n--\nmm/damon/core.c=3259=static unsigned long damos_quota_score(struct damon_ctx *c, struct damos *s)\n--\nmm/damon/core.c-3265-\tdamos_for_each_quota_goal(goal, quota) {\nmm/damon/core.c:3266:\t\tdamos_set_quota_goal_current_value(c, s, goal);\nmm/damon/core.c-3267-\t\thighest_score = max(highest_score,\n"
} |
| 13/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 13333 output: 37 thoughts: 24 Thoughts: Here's a summary of my thought process, as requested: **Diving into `mm/damon/core.c`** Okay, time to get my hands dirty. I'm going to focus my attention on the code block from line 3200 to 3280 within `mm/damon/core.c`. I need to understand what's happening within that specific segment. I know DAMON's core functionalities are complex, but this range is likely focused on a particular aspect. Could be initialization, a specific monitoring function, or perhaps handling some kind of data structure. I'll need to carefully parse the surrounding code if context is needed. I'm going to start by quickly scanning the lines, looking for any immediate keywords or function calls that jump out. That should give me a good jumping-off point to build a deeper understanding. Let's get to it. |
| 14/2 | 2026/09/20 20:10 | tool | read-file |
0mArgs:{
"File": "mm/damon/core.c",
"FirstLine": 3200,
"LineCount": 80
}Results: {
"Contents": "3200:\t\n3201:\tstatic void damos_set_quota_goal_current_value(struct damon_ctx *c,\n3202:\t\t\tstruct damos *s, struct damos_quota_goal *goal)\n3203:\t{\n3204:\t\tu64 now_psi_total;\n3205:\t\n3206:\t\tswitch (goal-\u003emetric) {\n3207:\t\tcase DAMOS_QUOTA_USER_INPUT:\n3208:\t\t\t/* User should already set goal-\u003ecurrent_value */\n3209:\t\t\tbreak;\n3210:\t\tcase DAMOS_QUOTA_SOME_MEM_PSI_US:\n3211:\t\t\tnow_psi_total = damos_get_some_mem_psi_total();\n3212:\t\t\t/* uninitialized last_psi_total; make no effect this round */\n3213:\t\t\tif (goal-\u003elast_psi_total == U64_MAX)\n3214:\t\t\t\tgoal-\u003ecurrent_value = goal-\u003etarget_value;\n3215:\t\t\telse\n3216:\t\t\t\tgoal-\u003ecurrent_value = now_psi_total -\n3217:\t\t\t\t\tgoal-\u003elast_psi_total;\n3218:\t\t\tgoal-\u003elast_psi_total = now_psi_total;\n3219:\t\t\tbreak;\n3220:\t\tcase DAMOS_QUOTA_NODE_MEM_USED_BP:\n3221:\t\tcase DAMOS_QUOTA_NODE_MEM_FREE_BP:\n3222:\t\t\tgoal-\u003ecurrent_value = damos_get_node_mem_bp(goal);\n3223:\t\t\tbreak;\n3224:\t\tcase DAMOS_QUOTA_NODE_MEMCG_USED_BP:\n3225:\t\tcase DAMOS_QUOTA_NODE_MEMCG_FREE_BP:\n3226:\t\t\tgoal-\u003ecurrent_value = damos_get_node_memcg_used_bp(goal);\n3227:\t\t\tbreak;\n3228:\t\tcase DAMOS_QUOTA_ACTIVE_MEM_BP:\n3229:\t\tcase DAMOS_QUOTA_INACTIVE_MEM_BP:\n3230:\t\t\tgoal-\u003ecurrent_value = damos_get_in_active_mem_bp(\n3231:\t\t\t\t\tgoal-\u003emetric == DAMOS_QUOTA_ACTIVE_MEM_BP);\n3232:\t\t\tbreak;\n3233:\t\tcase DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP:\n3234:\t\t\tgoal-\u003ecurrent_value = damos_get_node_eligible_mem_bp(c, s,\n3235:\t\t\t\t\tgoal-\u003enid);\n3236:\t\t\tbreak;\n3237:\t\tcase DAMOS_QUOTA_HUGEPAGE_MEM_BP:\n3238:\t\t\tgoal-\u003ecurrent_value = damos_hugepage_mem_bp();\n3239:\t\t\tbreak;\n3240:\t\tdefault:\n3241:\t\t\tbreak;\n3242:\t\t}\n3243:\t\tif (!goal-\u003ecomplement)\n3244:\t\t\treturn;\n3245:\t\n3246:\t\t/* updte current_value to complemented value */\n3247:\t\n3248:\t\t/* for user_input, users set complemented value on their own */\n3249:\t\tif (goal-\u003emetric == DAMOS_QUOTA_USER_INPUT)\n3250:\t\t\treturn;\n3251:\t\tif (goal-\u003emetric == DAMOS_QUOTA_SOME_MEM_PSI_US)\n3252:\t\t\tgoal-\u003ecurrent_value = s-\u003equota.reset_interval * 1000 -\n3253:\t\t\t\tgoal-\u003ecurrent_value;\n3254:\t\telse\n3255:\t\t\tgoal-\u003ecurrent_value = 10000 - goal-\u003ecurrent_value;\n3256:\t}\n3257:\t\n3258:\t/* Return the highest score since it makes schemes least aggressive */\n3259:\tstatic unsigned long damos_quota_score(struct damon_ctx *c, struct damos *s)\n3260:\t{\n3261:\t\tstruct damos_quota_goal *goal;\n3262:\t\tstruct damos_quota *quota = \u0026s-\u003equota;\n3263:\t\tunsigned long highest_score = 0;\n3264:\t\n3265:\t\tdamos_for_each_quota_goal(goal, quota) {\n3266:\t\t\tdamos_set_quota_goal_current_value(c, s, goal);\n3267:\t\t\thighest_score = max(highest_score,\n3268:\t\t\t\t\tmult_frac(goal-\u003ecurrent_value, 10000,\n3269:\t\t\t\t\t\tgoal-\u003etarget_value));\n3270:\t\t}\n3271:\t\n3272:\t\treturn highest_score;\n3273:\t}\n3274:\t\n3275:\tstatic void damos_goal_tune_esz_bp_consist(struct damon_ctx *c, struct damos *s)\n3276:\t{\n3277:\t\tstruct damos_quota *quota = \u0026s-\u003equota;\n3278:\t\tunsigned long score = damos_quota_score(c, s);\n3279:\t\n"
} |
| 15/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 14910 output: 31 thoughts: 1982 Thoughts: **Integer Overflow and Underflow Vulnerability in DAMON Quota Management** Okay, I see some potentially nasty integer issues here. Looking at the code, specifically lines like `goal->current_value = 10000 - goal->current_value;` and `goal->current_value = s->quota.reset_interval * 1000 - goal->current_value;`, there's a serious risk of integer underflow and overflow. If `goal->current_value` becomes larger than the reset interval times 1000, then we are in trouble. Multiplying by 10000 within the `mult_frac` function could easily overflow an `unsigned long`. That's a classic memory management bug waiting to happen. I'm also paying attention to the `complement` flag, which is stored and read via sysfs. I see it's defined and used in `mm/damon/sysfs-schemes.c` with `complement_show` and `complement_store`. We also have sysfs file creations related to it. The `damos_commit_quota_goals` function is copying `complement` flag via `damos_commit_quota_goal()`. This code modifies the quota goal current value calculation, which is concerning. This code, especially the stuff within the DAMON subsystem, is *definitely* reachable via sysfs, so it's worth fuzzing and thus `WorthFuzzing` should be `true`. It touches core memory management and sysfs interaction, which is a big red flag for potential issues. The code is in `/sys/kernel/mm/damon/admin/kdamonds/...`, so clearly reachable. So what configurations are needed? I'll need to enable `DAMON` and `DAMON_SYSFS` as a minimum. `DAMON_RECLAIM` and `DAMON_LRU_SORT` may also be relevant, but are potentially optional, because the core logic is based on `DAMON` and `DAMON_SYSFS`. |
| 16/2 | 2026/09/20 20:10 | tool | grepper |
0mArgs:{
"Expression": "config DAMON_",
"PathPrefix": "mm/damon/Kconfig"
}Results: {
"Output": "mm/damon/Kconfig=5=config DAMON\n--\nmm/damon/Kconfig-14-\nmm/damon/Kconfig:15:config DAMON_DEBUG_SANITY\nmm/damon/Kconfig-16-\tbool \"Check sanity of DAMON code\"\n--\nmm/damon/Kconfig-25-\nmm/damon/Kconfig:26:config DAMON_KUNIT_TEST\nmm/damon/Kconfig-27-\tbool \"Test for damon\" if !KUNIT_ALL_TESTS\n--\nmm/damon/Kconfig-37-\nmm/damon/Kconfig:38:config DAMON_VADDR\nmm/damon/Kconfig-39-\tbool \"Data access monitoring operations for virtual address spaces\"\n--\nmm/damon/Kconfig-46-\nmm/damon/Kconfig:47:config DAMON_PADDR\nmm/damon/Kconfig-48-\tbool \"Data access monitoring operations for the physical address space\"\n--\nmm/damon/Kconfig-55-\nmm/damon/Kconfig:56:config DAMON_VADDR_KUNIT_TEST\nmm/damon/Kconfig-57-\tbool \"Test for DAMON operations\" if !KUNIT_ALL_TESTS\n--\nmm/damon/Kconfig-67-\nmm/damon/Kconfig:68:config DAMON_SYSFS\nmm/damon/Kconfig-69-\tbool \"DAMON sysfs interface\"\n--\nmm/damon/Kconfig-75-\nmm/damon/Kconfig:76:config DAMON_SYSFS_KUNIT_TEST\nmm/damon/Kconfig-77-\tbool \"Test for damon sysfs interface\" if !KUNIT_ALL_TESTS\n--\nmm/damon/Kconfig-87-\nmm/damon/Kconfig:88:config DAMON_RECLAIM\nmm/damon/Kconfig-89-\tbool \"Build DAMON-based reclaim (DAMON_RECLAIM)\"\n--\nmm/damon/Kconfig-99-\nmm/damon/Kconfig:100:config DAMON_LRU_SORT\nmm/damon/Kconfig-101-\tbool \"Build DAMON-based LRU-lists sorting (DAMON_LRU_SORT)\"\n--\nmm/damon/Kconfig-107-\nmm/damon/Kconfig:108:config DAMON_STAT\nmm/damon/Kconfig-109-\tbool \"Build data access monitoring stat (DAMON_STAT)\"\n--\nmm/damon/Kconfig-115-\nmm/damon/Kconfig:116:config DAMON_STAT_ENABLED_DEFAULT\nmm/damon/Kconfig-117-\tbool \"Enable DAMON_STAT by default\"\n"
} |
| 17/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 18065 output: 34 thoughts: 286 Thoughts: **Analyzing DAMON Code Changes** Okay, let's start by quickly verifying the scope. I need to make sure I'm not chasing my tail in the wrong areas. First, I'll take a look at `samples/damon/mtier.c`. Ah, right, that's in the `samples/` directory, so that's user-space or sample code, not the core kernel. Good, I can skip that. And I'll note that `mm/damon/tests/core-kunit.h` is for KUnit testing. Got it. Now, let's zoom in on `FocusSymbols`. I need to pinpoint the functions directly implementing the changes or acting as API entrypoints. The key is identifying those impacted functions. Let's list the modified functions as my starting point. Okay, the listing mentions `damos_set_quota_goal_current_value` in `mm/damon/core.c`. Hmm, it's a static function. But I need to determine how it's used; whether it is inlined or not and what calls it. Is it even static, or is it exported or called by non-static functions? Let's check for it in `mm/damon/core.c` via grep. Alright, the callers are: `damos_quota_score(struct damon_ctx *c, struct damos *s)`. Interesting, which is itself called by: - `damos_goal_tune_esz_bp_consist()` - `damos_adjust_quota()` Now I need to understand the full caller hierarchy from this point forward, all within `mm/damon/core.c`. That will help determine the impact of these changes. |
| 18/2 | 2026/09/20 20:10 | tool | grepper |
0mArgs:{
"Expression": "damos_quota_score",
"PathPrefix": "mm/damon/core.c"
}Results: {
"Output": "mm/damon/core.c=3201=static void damos_set_quota_goal_current_value(struct damon_ctx *c,\n--\nmm/damon/core.c-3258-/* Return the highest score since it makes schemes least aggressive */\nmm/damon/core.c:3259:static unsigned long damos_quota_score(struct damon_ctx *c, struct damos *s)\nmm/damon/core.c-3260-{\n--\nmm/damon/core.c=3275=static void damos_goal_tune_esz_bp_consist(struct damon_ctx *c, struct damos *s)\n--\nmm/damon/core.c-3277-\tstruct damos_quota *quota = \u0026s-\u003equota;\nmm/damon/core.c:3278:\tunsigned long score = damos_quota_score(c, s);\nmm/damon/core.c-3279-\n--\nmm/damon/core.c=3284=static void damos_goal_tune_esz_bp_temporal(struct damon_ctx *c,\n--\nmm/damon/core.c-3287-\tstruct damos_quota *quota = \u0026s-\u003equota;\nmm/damon/core.c:3288:\tunsigned long score = damos_quota_score(c, s);\nmm/damon/core.c-3289-\n"
} |
| 19/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 19129 output: 39 thoughts: 38 Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue: **Investigating the `damos_goal_tune` Functions** Alright, time to get a handle on how `damos_goal_tune_esz_bp_consist` and `damos_goal_tune_esz_bp_temporal` are being utilized. I need to understand their context, so I'm going to track down every instance where those two functions are invoked. This will illuminate the specific scenarios they're designed for and, more broadly, how they fit into the larger tuning and optimization workflow for our DAMOS goals. Pinpointing the call sites is the crucial first step. Understanding the inputs passed, any surrounding logic, and the expected outcomes will quickly reveal their purpose. This is basic, but essential, code archaeology. Let's see where they're being *used*. |
| 20/2 | 2026/09/20 20:10 | tool | grepper |
0mArgs:{
"Expression": "damos_goal_tune_esz_bp_",
"PathPrefix": "mm/damon/core.c"
}Results: {
"Output": "mm/damon/core.c=3259=static unsigned long damos_quota_score(struct damon_ctx *c, struct damos *s)\n--\nmm/damon/core.c-3274-\nmm/damon/core.c:3275:static void damos_goal_tune_esz_bp_consist(struct damon_ctx *c, struct damos *s)\nmm/damon/core.c-3276-{\n--\nmm/damon/core.c-3283-\nmm/damon/core.c:3284:static void damos_goal_tune_esz_bp_temporal(struct damon_ctx *c,\nmm/damon/core.c-3285-\t\tstruct damos *s)\n--\nmm/damon/core.c=3301=static void damos_set_effective_quota(struct damon_ctx *ctx, struct damos *s)\n--\nmm/damon/core.c-3314-\t\tif (quota-\u003egoal_tuner == DAMOS_QUOTA_GOAL_TUNER_CONSIST)\nmm/damon/core.c:3315:\t\t\tdamos_goal_tune_esz_bp_consist(ctx, s);\nmm/damon/core.c-3316-\t\telse if (quota-\u003egoal_tuner == DAMOS_QUOTA_GOAL_TUNER_TEMPORAL)\nmm/damon/core.c:3317:\t\t\tdamos_goal_tune_esz_bp_temporal(ctx, s);\nmm/damon/core.c-3318-\t\tesz = quota-\u003eesz_bp / 10000;\n"
} |
| 21/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 19815 output: 41 thoughts: 164 Thoughts: **My DAMON Quota Exploration** Okay, so I'm diving deeper into this quota management within DAMON. Right now, I see that `damos_set_effective_quota` is called within `damos_adjust_quota()`. That's the core linkage. Now, I should probably understand how these functions are changing or interacting with it: * `damos_new_quota_goal` * `damos_commit_quota_goal` * `damos_commit_quota_goals` * `damos_set_quota_goal_current_value` I'll need to trace the evolution of the quota goal and see how it's handled within the DAMON core. Then, there's some activity in `mm/damon/sysfs-schemes.c`, specifically: * `complement_show` * `complement_store` These should handle the sysfs interface and display and configure the values. And finally, here's `damos_sysfs_add_quota_score`. I should probably clarify my understanding of this. It might be key to setting quotas and might be a critical piece to this whole picture. I'll need to dive into its definition and see what exactly it's doing. |
| 22/2 | 2026/09/20 20:10 | tool | read-file |
0mArgs:{
"File": "mm/damon/sysfs-schemes.c",
"FirstLine": 2890,
"LineCount": 40
}Results: {
"Contents": "2890:\t{\n2891:\t\tstruct damos_quota_goal *goal;\n2892:\t\tint i, err;\n2893:\t\n2894:\t\tfor (i = 0; i \u003c sysfs_goals-\u003enr; i++) {\n2895:\t\t\tstruct damos_sysfs_quota_goal *sysfs_goal =\n2896:\t\t\t\tsysfs_goals-\u003egoals_arr[i];\n2897:\t\n2898:\t\t\tif (!sysfs_goal-\u003etarget_value)\n2899:\t\t\t\tcontinue;\n2900:\t\n2901:\t\t\tgoal = damos_new_quota_goal(sysfs_goal-\u003emetric,\n2902:\t\t\t\t\tsysfs_goal-\u003ecomplement,\n2903:\t\t\t\t\tsysfs_goal-\u003etarget_value);\n2904:\t\t\tif (!goal)\n2905:\t\t\t\treturn -ENOMEM;\n2906:\t\t\tswitch (sysfs_goal-\u003emetric) {\n2907:\t\t\tcase DAMOS_QUOTA_USER_INPUT:\n2908:\t\t\t\tgoal-\u003ecurrent_value = sysfs_goal-\u003ecurrent_value;\n2909:\t\t\t\tbreak;\n2910:\t\t\tcase DAMOS_QUOTA_NODE_MEM_USED_BP:\n2911:\t\t\tcase DAMOS_QUOTA_NODE_MEM_FREE_BP:\n2912:\t\t\t\tgoal-\u003enid = sysfs_goal-\u003enid;\n2913:\t\t\t\tbreak;\n2914:\t\t\tcase DAMOS_QUOTA_NODE_MEMCG_USED_BP:\n2915:\t\t\tcase DAMOS_QUOTA_NODE_MEMCG_FREE_BP:\n2916:\t\t\t\terr = damon_sysfs_memcg_path_to_id(\n2917:\t\t\t\t\t\tsysfs_goal-\u003epath, \u0026goal-\u003ememcg_id);\n2918:\t\t\t\tif (err) {\n2919:\t\t\t\t\tdamos_destroy_quota_goal(goal);\n2920:\t\t\t\t\treturn err;\n2921:\t\t\t\t}\n2922:\t\t\t\tgoal-\u003enid = sysfs_goal-\u003enid;\n2923:\t\t\t\tbreak;\n2924:\t\t\tcase DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP:\n2925:\t\t\t\tgoal-\u003enid = sysfs_goal-\u003enid;\n2926:\t\t\t\tbreak;\n2927:\t\t\tdefault:\n2928:\t\t\t\tbreak;\n2929:\t\t\t}\n"
} |
| 23/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 20921 output: 41 thoughts: 29 Thoughts: Here's my thinking process: **Diving into DAMON's Scheme Configuration** Okay, so I need to track down a specific function within DAMON's sysfs interface for schemes. Let's start with the file `mm/damon/sysfs-schemes.c`. Given the context, this file probably handles the system file interface for creating and managing different DAMON schemes. Since I need a function name, let's zero in on line 2890. That is a pretty specific request, so hopefully, there will be a clear indication of a useful function name at that line. It might be a definition, a call, or part of a larger structure definition. Time to check it out. |
| 24/2 | 2026/09/20 20:10 | tool | read-file |
0mArgs:{
"File": "mm/damon/sysfs-schemes.c",
"FirstLine": 2880,
"LineCount": 15
}Results: {
"Contents": "2880:\t\t\t}\n2881:\t\n2882:\t\t\tdamos_add_filter(scheme, filter);\n2883:\t\t}\n2884:\t\treturn 0;\n2885:\t}\n2886:\t\n2887:\tstatic int damos_sysfs_add_quota_score(\n2888:\t\t\tstruct damos_sysfs_quota_goals *sysfs_goals,\n2889:\t\t\tstruct damos_quota *quota)\n2890:\t{\n2891:\t\tstruct damos_quota_goal *goal;\n2892:\t\tint i, err;\n2893:\t\n2894:\t\tfor (i = 0; i \u003c sysfs_goals-\u003enr; i++) {\n"
} |
| 25/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 21349 output: 36 thoughts: 46 Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue: **Investigating Quota Score Addition via Sysfs** Right, `damos_sysfs_add_quota_score`... I remember that function. It's the one responsible for pulling in those quota goals from the sysfs filesystem, isn't it? Okay, so that's its primary function. Now, a crucial follow-up question: where *exactly* is that function being called from? I need to understand the call graph to fully grasp its impact and potential interactions with other subsystems. Let's dig into the code and trace those calls. Time to check its usage. |
| 26/2 | 2026/09/20 20:10 | tool | grepper |
0mArgs:{
"Expression": "damos_sysfs_add_quota_score",
"PathPrefix": "mm/damon/"
}Results: {
"Output": "mm/damon/sysfs-schemes.c=2838=static int damon_sysfs_add_scheme_filters(struct damos *scheme,\n--\nmm/damon/sysfs-schemes.c-2886-\nmm/damon/sysfs-schemes.c:2887:static int damos_sysfs_add_quota_score(\nmm/damon/sysfs-schemes.c-2888-\t\tstruct damos_sysfs_quota_goals *sysfs_goals,\n--\nmm/damon/sysfs-schemes.c=2935=int damos_sysfs_set_quota_scores(struct damon_sysfs_schemes *sysfs_schemes,\n--\nmm/damon/sysfs-schemes.c-2952-\t\tsysfs_scheme = sysfs_schemes-\u003eschemes_arr[i];\nmm/damon/sysfs-schemes.c:2953:\t\terr = damos_sysfs_add_quota_score(sysfs_scheme-\u003equotas-\u003egoals,\nmm/damon/sysfs-schemes.c-2954-\t\t\t\t\u0026quota);\n--\nmm/damon/sysfs-schemes.c=3011=static struct damos *damon_sysfs_mk_scheme(\n--\nmm/damon/sysfs-schemes.c-3054-\nmm/damon/sysfs-schemes.c:3055:\terr = damos_sysfs_add_quota_score(sysfs_quotas-\u003egoals, \u0026scheme-\u003equota);\nmm/damon/sysfs-schemes.c-3056-\tif (err) {\n"
} |
| 27/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 21996 output: 36 thoughts: 51 Thoughts: Okay, here's my interpretation of that thought process, as if it were my own: **Investigating the `damos_sysfs_set_quota_scores` Function** Right, so `damos_sysfs_set_quota_scores` is living in `mm/damon/sysfs.c`. It's exposed, or at least used, in there. Good. Now, given that this function seems to be part of the DAMON (Data Access MONitor) subsystem's sysfs interface, my next step is clear. I need to understand how it's being *used*. Specifically, I'm going to track down every single call site for `damos_sysfs_set_quota_scores`. Understanding the callers will provide crucial context – how are these quota scores being set, what are the use cases, and what's the broader interaction with the DAMON framework? I need to build a complete picture of its role. Time to dive into the codebase and find those function calls. |
| 28/2 | 2026/09/20 20:10 | tool | grepper |
0mArgs:{
"Expression": "damos_sysfs_set_quota_scores",
"PathPrefix": "mm/damon/"
}Results: {
"Output": "mm/damon/sysfs-common.h=51=int damon_sysfs_schemes_clear_regions(\n--\nmm/damon/sysfs-common.h-53-\nmm/damon/sysfs-common.h:54:int damos_sysfs_set_quota_scores(struct damon_sysfs_schemes *sysfs_schemes,\nmm/damon/sysfs-common.h-55-\t\tstruct damon_ctx *ctx);\n--\nmm/damon/sysfs-schemes.c=2887=static int damos_sysfs_add_quota_score(\n--\nmm/damon/sysfs-schemes.c-2934-\nmm/damon/sysfs-schemes.c:2935:int damos_sysfs_set_quota_scores(struct damon_sysfs_schemes *sysfs_schemes,\nmm/damon/sysfs-schemes.c-2936-\t\tstruct damon_ctx *ctx)\n--\nmm/damon/sysfs.c=2480=static int damon_sysfs_commit_schemes_quota_goals(void *data)\n--\nmm/damon/sysfs.c-2493-\tsysfs_ctx = sysfs_kdamond-\u003econtexts-\u003econtexts_arr[0];\nmm/damon/sysfs.c:2494:\treturn damos_sysfs_set_quota_scores(sysfs_ctx-\u003eschemes, ctx);\nmm/damon/sysfs.c-2495-}\n"
} |
| 29/2 | 2026/09/20 20:10 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 22691 output: 249 thoughts: 1180 Thoughts: **DAMON Quota Goal Complement Logic: A Summary** Okay, let's break this down. My goal is to clearly document the changes and rationale for this DAMON patch, focusing on the core logic and entry points. First, I identified the key functions related to the new complement feature. These are the ones that are implementing the core logic, or are direct API entrypoints: * `damos_new_quota_goal` * `damos_set_quota_goal_current_value` * `damos_commit_quota_goal` * `damos_commit_quota_goals` * `complement_store` * `complement_show` * `damos_sysfs_set_quota_scores` I paid close attention to static functions, and confirmed that even though `complement_store` and `complement_show` are static, their addresses are taken, so they won't be inlined and are still important. I then identified the other modified functions: * `damon_lru_sort_add_quota_goals` in `mm/damon/lru_sort.c` * `damon_reclaim_apply_parameters` in `mm/damon/reclaim.c` I also verified that the necessary configuration options are enabled: `DAMON`, `DAMON_SYSFS`, `DAMON_RECLAIM`, `DAMON_LRU_SORT`, `DAMON_PADDR`, and `DAMON_VADDR`. I confirmed that `DAMON_SYSFS` does depend on `DAMON` and `SYSFS`, but `DAMON` and `DAMON_SYSFS` is very specific and accurate. No other dependencies seem to exist. The core of this patch introduces a boolean parameter `complement` to the `damos_quota_goal` structure. This enables inverting the auto-tuning quota metric. This changes the core memory management DAMON logic within `mm/damon/core.c`, specifically in calculations like `damos_set_quota_goal_current_value`, introducing potentially problematic arithmetic and the risk of underflow/overflow. The patch also exposes this feature through a new sysfs attribute. Given that this affects kernel code in the `mm/` subsystem, and exposes a user space entrypoint via sysfs, this makes this area prime for fuzzing. |
| 30/2 | 2026/09/20 20:11 | tool | set-results |
0mArgs:{
"EnableConfigs": [
"DAMON",
"DAMON_SYSFS",
"DAMON_RECLAIM",
"DAMON_LRU_SORT"
],
"FocusSymbols": [
"damos_set_quota_goal_current_value",
"complement_store",
"complement_show",
"damos_new_quota_goal",
"damos_commit_quota_goal",
"damos_commit_quota_goals",
"damos_sysfs_set_quota_scores"
],
"Reasoning": "The patch modifies memory management (mm/damon) by adding a 'complement' option to DAMOS quota goals. This introduces new sysfs handlers (complement_store, complement_show) and modifies quota calculation logic in damos_set_quota_goal_current_value(), where arithmetic operations on goal values (e.g. subtracting from 10000 or reset_interval * 1000) could potentially underflow/overflow. The modified code is reachable from userspace via the DAMON sysfs interface in standard virtualized environments.",
"WorthFuzzing": true
}Results: {
"EnableConfigs": [
"DAMON",
"DAMON_SYSFS",
"DAMON_RECLAIM",
"DAMON_LRU_SORT"
],
"FocusSymbols": [
"damos_set_quota_goal_current_value",
"complement_store",
"complement_show",
"damos_new_quota_goal",
"damos_commit_quota_goal",
"damos_commit_quota_goals",
"damos_sysfs_set_quota_scores"
],
"Reasoning": "The patch modifies memory management (mm/damon) by adding a 'complement' option to DAMOS quota goals. This introduces new sysfs handlers (complement_store, complement_show) and modifies quota calculation logic in damos_set_quota_goal_current_value(), where arithmetic operations on goal values (e.g. subtracting from 10000 or reset_interval * 1000) could potentially underflow/overflow. The modified code is reachable from userspace via the DAMON sysfs interface in standard virtualized environments.",
"WorthFuzzing": true
} |
| 31/1 | 2026/09/20 20:11 | action | If |
0mArgs:{
"WorthFuzzing": true
}Results: null |
| 32/2 | 2026/09/20 20:11 | agent | kmsan-evaluator |
0mModel:core Args: null Results: {
"KMSANReasoning": "The patch adds a boolean 'complement' field to DAMON's quota goal structures (struct damos_quota_goal and struct damos_sysfs_quota_goal) and exposes it via sysfs. \n\n1. Allocation \u0026 Initialization: Sysfs quota goal instances are allocated using kzalloc_obj(), which zeroes all fields by default, while kernel quota goal instances created via damos_new_quota_goal() explicitly initialize goal-\u003ecomplement = complement.\n2. User-space Exposure: The sysfs interface exposes this property via sysfs_emit() with formatted string output ('Y' or 'N'), avoiding any raw structure copying or padding leak to userspace (no copy_to_user of structs with padding).\n3. Arithmetic / Control Flow: The arithmetic operations performed on goal-\u003ecurrent_value based on complement do not alter buffer bounds, length calculations, or memory accesses.\n\nBecause no uninitialized memory can be read or leaked, there is no uninitialized memory risk that requires KMSAN. Standard KASAN/sanitizer configurations are sufficient to test these changes.",
"NeedsKMSAN": false
}Instruction: You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.
CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
a comprehensive suite of debugging tools and sanitizers, including KASAN
(out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
(locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
or page allocations) and kernel-to-user memory info-leaks.
Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.
Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.
Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
attributes, ioctl output arguments, socket options, or BPF buffers) where fields
or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
uninitialized bytes of existing buffers.
Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
dereferences, locking deadlocks, or use-after-free bugs (these are already caught
by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.
Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit b05a7bec58c8cc3b3748c793cdaa49f65c3b7d63
Author: syz-cluster <triage@syzkaller.com>
Date: Sun Sep 20 20:10:10 2026 +0000
syz-cluster: applied patch under review
diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
index 55df688ea596f..4acb2015c2f4f 100644
--- a/Documentation/ABI/testing/sysfs-kernel-mm-damon
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
@@ -375,6 +375,12 @@ Contact: SJ Park <sj@kernel.org>
Description: Writing to and reading from this file sets and gets the quota
auto-tuning goal metric.
+What: /sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/goals/<G>/complement
+Date: Sep 2026
+Contact: SJ Park <sj@kernel.org>
+Description: Writing to and reading from this file sets and gets whether to
+ use the complement value of the quota auto-tuning goal metric.
+
What: /sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/goals/<G>/target_value
Date: Nov 2023
Contact: SJ Park <sj@kernel.org>
diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index ba47255448564..b3f2e591fb7e4 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -98,7 +98,8 @@ comma (",").
│ │ │ │ │ │ │ fail_charge_num,fail_charge_denom
│ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil
│ │ │ │ │ │ │ │ :ref:`goals <sysfs_schemes_quota_goals>`/nr_goals
- │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value,nid,path
+ │ │ │ │ │ │ │ │ │ 0/target_metric,complement,target_value,
+ │ │ │ │ │ │ │ │ │ current_value,nid,path
│ │ │ │ │ │ │ :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low
│ │ │ │ │ │ │ :ref:`{core_,ops_,}filters <sysfs_filters>`/nr_filters
│ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,damon_target_idx,min,max
@@ -493,11 +494,11 @@ to ``N-1``. Each directory represents each goal and current achievement.
Among the multiple feedback, the best one is used.
Each goal directory contains five files, namely ``target_metric``,
-``target_value``, ``current_value``, ``nid``, and ``path``. Users can set and
-get the five parameters for the quota auto-tuning goals that specified on the
-:ref:`design doc <damon_design_damos_quotas_auto_tuning>` by writing to and
-reading from each of the files. Because the kernel does not update
-``current_value``, reading it only makes sense when ``target_metric`` is
+``complement``, ``target_value``, ``current_value``, ``nid``, and ``path``.
+Users can set and get the six parameters for the quota auto-tuning goals that
+specified on the :ref:`design doc <damon_design_damos_quotas_auto_tuning>` by
+writing to and reading from each of the files. Because the kernel does not
+update ``current_value``, reading it only makes sense when ``target_metric`` is
``user_input``. Note that users should further write
``commit_schemes_quota_goals`` to the ``state`` file of the :ref:`kdamond
directory <sysfs_kdamond>` to pass the feedback to DAMON.
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index e82390e77a70a..c82be80738c45 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -702,10 +702,10 @@ There are two such tuning algorithms that users can select as they need.
that the zero quota is a valid quota, and therefore ``qt_exceeds`` :ref:`stat
<damon_design_damos_stat>` will keep increasing in this case.
-The goal can be specified with five parameters, namely ``target_metric``,
-``target_value``, ``current_value``, ``nid`` and ``path``. The auto-tuning
-mechanism tries to make ``current_value`` of ``target_metric`` be same to
-``target_value``.
+The goal can be specified with six parameters, namely ``target_metric``,
+``complement``, ``target_value``, ``current_value``, ``nid`` and ``path``. The
+auto-tuning mechanism tries to make ``current_value`` of ``complement``-ed
+``target_metric`` be same to ``target_value``.
- ``user_input``: User-provided value. Users could use any metric that they
has interest in for the value. Use space main workload's latency or
@@ -733,6 +733,11 @@ mechanism tries to make ``current_value`` of ``target_metric`` be same to
- ``hugepage_mem_bp``: Total huge page to total used memory ratio in bp
(1/10,000).
+``complement`` is a boolean parameter that determines whether to use
+complemented value of the target metric. For example, if ``complement`` is set
+and target metric is ``active_mem_bp``, it is effectively same to
+``inactive_mem_bp``.
+
``nid`` is optionally required for ``node_mem_used_bp``, ``node_mem_free_bp``,
``node_memcg_used_bp``, ``node_memcg_free_bp`` and ``node_eligible_mem_bp`` to
point the specific NUMA node.
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 836353c4ab9aa..754752d891ca2 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -175,6 +175,7 @@ enum damos_quota_goal_metric {
/**
* struct damos_quota_goal - DAMOS scheme quota auto-tuning goal.
* @metric: Metric to be used for representing the goal.
+ * @complement: Use the complement of the metric.
* @target_value: Target value of @metric to achieve with the tuning.
* @current_value: Current value of @metric.
* @nid: Node id.
@@ -197,6 +198,7 @@ enum damos_quota_goal_metric {
*/
struct damos_quota_goal {
enum damos_quota_goal_metric metric;
+ bool complement;
unsigned long target_value;
unsigned long current_value;
/* metric-dependent fields */
@@ -1095,7 +1097,7 @@ bool damos_filter_for_ops(enum damos_filter_type type);
void damos_destroy_filter(struct damos_filter *f);
struct damos_quota_goal *damos_new_quota_goal(
- enum damos_quota_goal_metric metric,
+ enum damos_quota_goal_metric metric, bool complement,
unsigned long target_value);
void damos_add_quota_goal(struct damos_quota *q, struct damos_quota_goal *g);
void damos_destroy_quota_goal(struct damos_quota_goal *goal);
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 2258b72da7a78..2dc1ee96814d0 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -691,7 +691,7 @@ void damos_destroy_filter(struct damos_filter *f)
}
struct damos_quota_goal *damos_new_quota_goal(
- enum damos_quota_goal_metric metric,
+ enum damos_quota_goal_metric metric, bool complement,
unsigned long target_value)
{
struct damos_quota_goal *goal;
@@ -700,6 +700,7 @@ struct damos_quota_goal *damos_new_quota_goal(
if (!goal)
return NULL;
goal->metric = metric;
+ goal->complement = complement;
goal->target_value = target_value;
if (metric == DAMOS_QUOTA_SOME_MEM_PSI_US)
goal->last_psi_total = U64_MAX;
@@ -1224,6 +1225,7 @@ static int damos_commit_quota_goal(
if (!src->target_value)
return -EINVAL;
dst->metric = src->metric;
+ dst->complement = src->complement;
dst->target_value = src->target_value;
if (dst->metric == DAMOS_QUOTA_USER_INPUT)
dst->current_value = src->current_value;
@@ -1261,8 +1263,8 @@ int damos_commit_quota_goals(struct damos_quota *dst, struct damos_quota *src)
damos_for_each_quota_goal_safe(src_goal, next, src) {
if (j++ < i)
continue;
- new_goal = damos_new_quota_goal(
- src_goal->metric, src_goal->target_value);
+ new_goal = damos_new_quota_goal(src_goal->metric, false,
+ src_goal->target_value);
if (!new_goal)
return -ENOMEM;
err = damos_commit_quota_goal(new_goal, src_goal);
@@ -3238,6 +3240,19 @@ static void damos_set_quota_goal_current_value(struct damon_ctx *c,
default:
break;
}
+ if (!goal->complement)
+ return;
+
+ /* updte current_value to complemented value */
+
+ /* for user_input, users set complemented value on their own */
+ if (goal->metric == DAMOS_QUOTA_USER_INPUT)
+ return;
+ if (goal->metric == DAMOS_QUOTA_SOME_MEM_PSI_US)
+ goal->current_value = s->quota.reset_interval * 1000 -
+ goal->current_value;
+ else
+ goal->current_value = 10000 - goal->current_value;
}
/* Return the highest score since it makes schemes least aggressive */
diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index ad8e86dd3a93e..aca90b8115b8d 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -233,12 +233,13 @@ static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,
if (!active_mem_bp)
return 0;
- goal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, active_mem_bp);
+ goal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, false,
+ active_mem_bp);
if (!goal)
return -ENOMEM;
damos_add_quota_goal(&hot_scheme->quota, goal);
/* aim 0.2 % goal conflict, to keep little ping pong */
- goal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP,
+ goal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP, false,
10000 - active_mem_bp + 2);
if (!goal)
return -ENOMEM;
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index 42a2c9cb13431..014b0779ea6dd 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -233,7 +233,7 @@ static int damon_reclaim_apply_parameters(void)
damon_set_schemes(param_ctx, &scheme, 1);
if (quota_mem_pressure_us) {
- goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US,
+ goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US, false,
quota_mem_pressure_us);
if (!goal)
goto out;
@@ -241,7 +241,8 @@ static int damon_reclaim_apply_parameters(void)
}
if (quota_autotune_feedback) {
- goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000);
+ goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, false,
+ 10000);
if (!goal)
goto out;
goal->current_value = quota_autotune_feedback;
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index bfb6f0bc3f213..8f083611741fd 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1220,6 +1220,7 @@ static const struct kobj_type damon_sysfs_watermarks_ktype = {
struct damos_sysfs_quota_goal {
struct kobject kobj;
enum damos_quota_goal_metric metric;
+ bool complement;
unsigned long target_value;
unsigned long current_value;
int nid;
@@ -1316,6 +1317,30 @@ static ssize_t target_metric_store(struct kobject *kobj,
return -EINVAL;
}
+static ssize_t complement_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct damos_sysfs_quota_goal *goal = container_of(kobj,
+ struct damos_sysfs_quota_goal, kobj);
+
+ return sysfs_emit(buf, "%c\n", goal->complement ? 'Y' : 'N');
+}
+
+static ssize_t complement_store(struct kobject *kobj,
+ struct kobj_attribute *attr, const char *buf, size_t count)
+{
+ struct damos_sysfs_quota_goal *goal = container_of(kobj,
+ struct damos_sysfs_quota_goal, kobj);
+ bool complement;
+ int err = kstrtobool(buf, &complement);
+
+ if (err)
+ return err;
+
+ goal->complement = complement;
+ return count;
+}
+
static ssize_t target_value_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -1424,6 +1449,9 @@ static void damos_sysfs_quota_goal_release(struct kobject *kobj)
static struct kobj_attribute damos_sysfs_quota_goal_target_metric_attr =
__ATTR_RW_MODE(target_metric, 0600);
+static struct kobj_attribute damos_sysfs_quota_goal_complement_attr =
+ __ATTR_RW_MODE(complement, 0600);
+
static struct kobj_attribute damos_sysfs_quota_goal_target_value_attr =
__ATTR_RW_MODE(target_value, 0600);
@@ -1438,6 +1466,7 @@ static struct kobj_attribute damos_sysfs_quota_goal_path_attr =
static struct attribute *damos_sysfs_quota_goal_attrs[] = {
&damos_sysfs_quota_goal_target_metric_attr.attr,
+ &damos_sysfs_quota_goal_complement_attr.attr,
&damos_sysfs_quota_goal_target_value_attr.attr,
&damos_sysfs_quota_goal_current_value_attr.attr,
&damos_sysfs_quota_goal_nid_attr.attr,
@@ -2870,6 +2899,7 @@ static int damos_sysfs_add_quota_score(
continue;
goal = damos_new_quota_goal(sysfs_goal->metric,
+ sysfs_goal->complement,
sysfs_goal->target_value);
if (!goal)
return -ENOMEM;
diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 5ff0436c58441..2394e074ef628 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -819,6 +819,7 @@ static void damos_test_commit_quota_goal_for(struct kunit *test,
damos_commit_quota_goal(dst, src);
KUNIT_EXPECT_EQ(test, dst->metric, src->metric);
+ KUNIT_EXPECT_EQ(test, dst->complement, src->complement);
KUNIT_EXPECT_EQ(test, dst->target_value, src->target_value);
if (src->metric == DAMOS_QUOTA_USER_INPUT)
KUNIT_EXPECT_EQ(test, dst->current_value, src->current_value);
@@ -862,6 +863,7 @@ static void damos_test_commit_quota_goal(struct kunit *test)
damos_test_commit_quota_goal_for(test, &dst,
&(struct damos_quota_goal){
.metric = DAMOS_QUOTA_USER_INPUT,
+ .complement = true,
.target_value = 789,
.current_value = 12});
damos_test_commit_quota_goal_for(test, &dst,
@@ -929,7 +931,7 @@ static void damos_test_commit_quota_goals_for(struct kunit *test,
* damos_commit_quota_goals() will kfree() the dst goals.
* Make it kfree()-able.
*/
- goal = damos_new_quota_goal(dst_goals[i].metric,
+ goal = damos_new_quota_goal(dst_goals[i].metric, false,
dst_goals[i].target_value);
if (!goal)
goto out;
diff --git a/samples/damon/mtier.c b/samples/damon/mtier.c
index 27dc88bdf7a0e..a2e311082cd4b 100644
--- a/samples/damon/mtier.c
+++ b/samples/damon/mtier.c
@@ -163,7 +163,7 @@ static struct damon_ctx *damon_sample_mtier_build_ctx(bool promote)
damon_set_schemes(ctx, &scheme, 1);
quota_goal = damos_new_quota_goal(
promote ? DAMOS_QUOTA_NODE_MEM_USED_BP :
- DAMOS_QUOTA_NODE_MEM_FREE_BP,
+ DAMOS_QUOTA_NODE_MEM_FREE_BP, false,
promote ? node0_mem_used_bp : node0_mem_free_bp);
if (!quota_goal)
goto free_out;
|
| 33/3 | 2026/09/20 20:11 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 7207 output: 41 thoughts: 644 Thoughts: **Analyzing the DAMON Quota Goal Patch for KMSAN Fuzzing Potential** Okay, let's break this down. My initial assessment is whether this patch warrants a dedicated KMSAN fuzzing session. First, I need to understand what this patch is *actually* doing. From the file modifications, it's clear this is adding a `complement` boolean attribute to DAMON's quota goals. Basically, DAMON's quota auto-tuning goals now get a "complement" flag. Looking at the files, it seems pretty straightforward: * **Documentation:** Updates to documentation (`ABI/testing`, `admin-guide`, `design`) to reflect the new attribute. Good hygiene. * **`include/linux/damon.h`:** The core change. A `bool complement` field is added to the `damos_quota_goal` struct. The `damos_new_quota_goal` function is updated to accept this boolean. * **`mm/damon/core.c`:** The `complement` value is set in `damos_new_quota_goal` and copied during commit operations. The interesting part is the `damos_set_quota_goal_current_value` function. This is where the logic for the `complement` flag comes into play. It appears that when complement is false, nothing happens. But when complement is true, the `current_value` is updated to a *complemented* value. There's some specific handling based on the `metric` type (e.g., `DAMOS_QUOTA_USER_INPUT` gets skipped). For `SOME_MEM_PSI_US`, it appears to complement the current value. Otherwise, it's 10000 - current value. * **`mm/damon/lru_sort.c` & `mm/damon/reclaim.c`:** These are passing `false` to the new functions. So it seems like existing usages might be opting out or have to be updated to be complement aware. * **`mm/damon/sysfs-schemes.c`:** This is where the attribute becomes user-facing. The `damos_sysfs_quota_goal` struct is updated to include the `complement` boolean. There are new `complement_show` and `complement_store` functions for sysfs interaction and an attribute added to sysfs. Also, `damos_sysfs_add_quota_score` copies this value. So the sysfs interface is the primary way the complement is enabled. * **`mm/damon/tests/core-kunit.h` & `samples/damon/mtier.c`:** Tests and a sample have been updated. My next step is to examine how `struct damos_sysfs_quota_goal` is allocated, especially within `mm/damon/sysfs-schemes.c`. I need to understand how that structure is created and how data flows into it. I'll need to use `grepper` or `read-file` to get a handle on that. From here, I'll assess the potential KMSAN risk based on those points, particularly focusing on the `damos_set_quota_goal_current_value` function and any pointer dereferences or potential integer overflows that could be triggered with the new `complement` logic. The sysfs interface is another area of interest, as it exposes this functionality to userspace. |
| 34/3 | 2026/09/20 20:11 | tool | grepper |
0mArgs:{
"Expression": "damos_sysfs_quota_goal",
"PathPrefix": "mm/damon/sysfs-schemes.c"
}Results: {
"Output": "mm/damon/sysfs-schemes.c=1210=static const struct kobj_type damon_sysfs_watermarks_ktype = {\n--\nmm/damon/sysfs-schemes.c-1219-\nmm/damon/sysfs-schemes.c:1220:struct damos_sysfs_quota_goal {\nmm/damon/sysfs-schemes.c-1221-\tstruct kobject kobj;\n--\nmm/damon/sysfs-schemes.c-1229-\nmm/damon/sysfs-schemes.c:1230:static struct damos_sysfs_quota_goal *damos_sysfs_quota_goal_alloc(void)\nmm/damon/sysfs-schemes.c-1231-{\nmm/damon/sysfs-schemes.c:1232:\treturn kzalloc_obj(struct damos_sysfs_quota_goal);\nmm/damon/sysfs-schemes.c-1233-}\n--\nmm/damon/sysfs-schemes.c=1284=static ssize_t target_metric_show(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1286-{\nmm/damon/sysfs-schemes.c:1287:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\nmm/damon/sysfs-schemes.c:1288:\t\t\tstruct damos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1289-\tint i;\n--\nmm/damon/sysfs-schemes.c=1301=static ssize_t target_metric_store(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1303-{\nmm/damon/sysfs-schemes.c:1304:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\nmm/damon/sysfs-schemes.c:1305:\t\t\tstruct damos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1306-\tint i;\n--\nmm/damon/sysfs-schemes.c=1320=static ssize_t complement_show(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1322-{\nmm/damon/sysfs-schemes.c:1323:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\nmm/damon/sysfs-schemes.c:1324:\t\t\tstruct damos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1325-\n--\nmm/damon/sysfs-schemes.c=1329=static ssize_t complement_store(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1331-{\nmm/damon/sysfs-schemes.c:1332:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\nmm/damon/sysfs-schemes.c:1333:\t\t\tstruct damos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1334-\tbool complement;\n--\nmm/damon/sysfs-schemes.c=1344=static ssize_t target_value_show(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1346-{\nmm/damon/sysfs-schemes.c:1347:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj, struct\nmm/damon/sysfs-schemes.c:1348:\t\t\tdamos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1349-\n--\nmm/damon/sysfs-schemes.c=1353=static ssize_t target_value_store(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1355-{\nmm/damon/sysfs-schemes.c:1356:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj, struct\nmm/damon/sysfs-schemes.c:1357:\t\t\tdamos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1358-\tint err = kstrtoul(buf, 0, \u0026goal-\u003etarget_value);\n--\nmm/damon/sysfs-schemes.c=1363=static ssize_t current_value_show(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1365-{\nmm/damon/sysfs-schemes.c:1366:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj, struct\nmm/damon/sysfs-schemes.c:1367:\t\t\tdamos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1368-\n--\nmm/damon/sysfs-schemes.c=1372=static ssize_t current_value_store(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1374-{\nmm/damon/sysfs-schemes.c:1375:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj, struct\nmm/damon/sysfs-schemes.c:1376:\t\t\tdamos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1377-\tint err = kstrtoul(buf, 0, \u0026goal-\u003ecurrent_value);\n--\nmm/damon/sysfs-schemes.c=1383=static ssize_t nid_show(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1385-{\nmm/damon/sysfs-schemes.c:1386:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj, struct\nmm/damon/sysfs-schemes.c:1387:\t\t\tdamos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1388-\n--\nmm/damon/sysfs-schemes.c=1393=static ssize_t nid_store(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1395-{\nmm/damon/sysfs-schemes.c:1396:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj, struct\nmm/damon/sysfs-schemes.c:1397:\t\t\tdamos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1398-\tint err = kstrtoint(buf, 0, \u0026goal-\u003enid);\n--\nmm/damon/sysfs-schemes.c=1404=static ssize_t path_show(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1406-{\nmm/damon/sysfs-schemes.c:1407:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\nmm/damon/sysfs-schemes.c:1408:\t\t\tstruct damos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1409-\tint len;\n--\nmm/damon/sysfs-schemes.c=1418=static ssize_t path_store(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1420-{\nmm/damon/sysfs-schemes.c:1421:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\nmm/damon/sysfs-schemes.c:1422:\t\t\tstruct damos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1423-\tchar *path = kmalloc_array(size_add(count, 1), sizeof(*path),\n--\nmm/damon/sysfs-schemes.c-1439-\nmm/damon/sysfs-schemes.c:1440:static void damos_sysfs_quota_goal_release(struct kobject *kobj)\nmm/damon/sysfs-schemes.c-1441-{\nmm/damon/sysfs-schemes.c:1442:\tstruct damos_sysfs_quota_goal *goal = container_of(kobj,\nmm/damon/sysfs-schemes.c:1443:\t\t\tstruct damos_sysfs_quota_goal, kobj);\nmm/damon/sysfs-schemes.c-1444-\n--\nmm/damon/sysfs-schemes.c-1448-\nmm/damon/sysfs-schemes.c:1449:static struct kobj_attribute damos_sysfs_quota_goal_target_metric_attr =\nmm/damon/sysfs-schemes.c-1450-\t\t__ATTR_RW_MODE(target_metric, 0600);\nmm/damon/sysfs-schemes.c-1451-\nmm/damon/sysfs-schemes.c:1452:static struct kobj_attribute damos_sysfs_quota_goal_complement_attr =\nmm/damon/sysfs-schemes.c-1453-\t\t__ATTR_RW_MODE(complement, 0600);\nmm/damon/sysfs-schemes.c-1454-\nmm/damon/sysfs-schemes.c:1455:static struct kobj_attribute damos_sysfs_quota_goal_target_value_attr =\nmm/damon/sysfs-schemes.c-1456-\t\t__ATTR_RW_MODE(target_value, 0600);\nmm/damon/sysfs-schemes.c-1457-\nmm/damon/sysfs-schemes.c:1458:static struct kobj_attribute damos_sysfs_quota_goal_current_value_attr =\nmm/damon/sysfs-schemes.c-1459-\t\t__ATTR_RW_MODE(current_value, 0600);\nmm/damon/sysfs-schemes.c-1460-\nmm/damon/sysfs-schemes.c:1461:static struct kobj_attribute damos_sysfs_quota_goal_nid_attr =\nmm/damon/sysfs-schemes.c-1462-\t\t__ATTR_RW_MODE(nid, 0600);\nmm/damon/sysfs-schemes.c-1463-\nmm/damon/sysfs-schemes.c:1464:static struct kobj_attribute damos_sysfs_quota_goal_path_attr =\nmm/damon/sysfs-schemes.c-1465-\t\t__ATTR_RW_MODE(path, 0600);\nmm/damon/sysfs-schemes.c-1466-\nmm/damon/sysfs-schemes.c:1467:static struct attribute *damos_sysfs_quota_goal_attrs[] = {\nmm/damon/sysfs-schemes.c:1468:\t\u0026damos_sysfs_quota_goal_target_metric_attr.attr,\nmm/damon/sysfs-schemes.c:1469:\t\u0026damos_sysfs_quota_goal_complement_attr.attr,\nmm/damon/sysfs-schemes.c:1470:\t\u0026damos_sysfs_quota_goal_target_value_attr.attr,\nmm/damon/sysfs-schemes.c:1471:\t\u0026damos_sysfs_quota_goal_current_value_attr.attr,\nmm/damon/sysfs-schemes.c:1472:\t\u0026damos_sysfs_quota_goal_nid_attr.attr,\nmm/damon/sysfs-schemes.c:1473:\t\u0026damos_sysfs_quota_goal_path_attr.attr,\nmm/damon/sysfs-schemes.c-1474-\tNULL,\nmm/damon/sysfs-schemes.c-1475-};\nmm/damon/sysfs-schemes.c:1476:ATTRIBUTE_GROUPS(damos_sysfs_quota_goal);\nmm/damon/sysfs-schemes.c-1477-\nmm/damon/sysfs-schemes.c:1478:static const struct kobj_type damos_sysfs_quota_goal_ktype = {\nmm/damon/sysfs-schemes.c:1479:\t.release = damos_sysfs_quota_goal_release,\nmm/damon/sysfs-schemes.c-1480-\t.sysfs_ops = \u0026kobj_sysfs_ops,\nmm/damon/sysfs-schemes.c:1481:\t.default_groups = damos_sysfs_quota_goal_groups,\nmm/damon/sysfs-schemes.c-1482-};\n--\nmm/damon/sysfs-schemes.c-1487-\nmm/damon/sysfs-schemes.c:1488:struct damos_sysfs_quota_goals {\nmm/damon/sysfs-schemes.c-1489-\tstruct kobject kobj;\nmm/damon/sysfs-schemes.c:1490:\tstruct damos_sysfs_quota_goal **goals_arr;\t/* counted by nr */\nmm/damon/sysfs-schemes.c-1491-\tint nr;\n--\nmm/damon/sysfs-schemes.c-1493-\nmm/damon/sysfs-schemes.c:1494:static struct damos_sysfs_quota_goals *damos_sysfs_quota_goals_alloc(void)\nmm/damon/sysfs-schemes.c-1495-{\nmm/damon/sysfs-schemes.c:1496:\treturn kzalloc_obj(struct damos_sysfs_quota_goals);\nmm/damon/sysfs-schemes.c-1497-}\nmm/damon/sysfs-schemes.c-1498-\nmm/damon/sysfs-schemes.c:1499:static void damos_sysfs_quota_goals_rm_dirs(\nmm/damon/sysfs-schemes.c:1500:\t\tstruct damos_sysfs_quota_goals *goals)\nmm/damon/sysfs-schemes.c-1501-{\nmm/damon/sysfs-schemes.c:1502:\tstruct damos_sysfs_quota_goal **goals_arr = goals-\u003egoals_arr;\nmm/damon/sysfs-schemes.c-1503-\tint i;\n--\nmm/damon/sysfs-schemes.c-1513-\nmm/damon/sysfs-schemes.c:1514:static int damos_sysfs_quota_goals_add_dirs(\nmm/damon/sysfs-schemes.c:1515:\t\tstruct damos_sysfs_quota_goals *goals, int nr_goals)\nmm/damon/sysfs-schemes.c-1516-{\nmm/damon/sysfs-schemes.c:1517:\tstruct damos_sysfs_quota_goal **goals_arr, *goal;\nmm/damon/sysfs-schemes.c-1518-\tint err, i;\nmm/damon/sysfs-schemes.c-1519-\nmm/damon/sysfs-schemes.c:1520:\tdamos_sysfs_quota_goals_rm_dirs(goals);\nmm/damon/sysfs-schemes.c-1521-\tif (!nr_goals)\n--\nmm/damon/sysfs-schemes.c-1530-\tfor (i = 0; i \u003c nr_goals; i++) {\nmm/damon/sysfs-schemes.c:1531:\t\tgoal = damos_sysfs_quota_goal_alloc();\nmm/damon/sysfs-schemes.c-1532-\t\tif (!goal) {\nmm/damon/sysfs-schemes.c:1533:\t\t\tdamos_sysfs_quota_goals_rm_dirs(goals);\nmm/damon/sysfs-schemes.c-1534-\t\t\treturn -ENOMEM;\n--\nmm/damon/sysfs-schemes.c-1537-\t\terr = kobject_init_and_add(\u0026goal-\u003ekobj,\nmm/damon/sysfs-schemes.c:1538:\t\t\t\t\u0026damos_sysfs_quota_goal_ktype, \u0026goals-\u003ekobj,\nmm/damon/sysfs-schemes.c-1539-\t\t\t\t\"%d\", i);\n--\nmm/damon/sysfs-schemes.c-1541-\t\t\tkobject_put(\u0026goal-\u003ekobj);\nmm/damon/sysfs-schemes.c:1542:\t\t\tdamos_sysfs_quota_goals_rm_dirs(goals);\nmm/damon/sysfs-schemes.c-1543-\t\t\treturn err;\n--\nmm/damon/sysfs-schemes.c=1552=static ssize_t nr_goals_show(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1554-{\nmm/damon/sysfs-schemes.c:1555:\tstruct damos_sysfs_quota_goals *goals = container_of(kobj,\nmm/damon/sysfs-schemes.c:1556:\t\t\tstruct damos_sysfs_quota_goals, kobj);\nmm/damon/sysfs-schemes.c-1557-\n--\nmm/damon/sysfs-schemes.c=1561=static ssize_t nr_goals_store(struct kobject *kobj,\n--\nmm/damon/sysfs-schemes.c-1563-{\nmm/damon/sysfs-schemes.c:1564:\tstruct damos_sysfs_quota_goals *goals;\nmm/damon/sysfs-schemes.c-1565-\tint nr, err = kstrtoint(buf, 0, \u0026nr);\n--\nmm/damon/sysfs-schemes.c-1571-\nmm/damon/sysfs-schemes.c:1572:\tgoals = container_of(kobj, struct damos_sysfs_quota_goals, kobj);\nmm/damon/sysfs-schemes.c-1573-\n--\nmm/damon/sysfs-schemes.c-1575-\t\treturn -EBUSY;\nmm/damon/sysfs-schemes.c:1576:\terr = damos_sysfs_quota_goals_add_dirs(goals, nr);\nmm/damon/sysfs-schemes.c-1577-\tmutex_unlock(\u0026damon_sysfs_lock);\n--\nmm/damon/sysfs-schemes.c-1583-\nmm/damon/sysfs-schemes.c:1584:static void damos_sysfs_quota_goals_release(struct kobject *kobj)\nmm/damon/sysfs-schemes.c-1585-{\nmm/damon/sysfs-schemes.c:1586:\tkfree(container_of(kobj, struct damos_sysfs_quota_goals, kobj));\nmm/damon/sysfs-schemes.c-1587-}\nmm/damon/sysfs-schemes.c-1588-\nmm/damon/sysfs-schemes.c:1589:static struct kobj_attribute damos_sysfs_quota_goals_nr_attr =\nmm/damon/sysfs-schemes.c-1590-\t\t__ATTR_RW_MODE(nr_goals, 0600);\nmm/damon/sysfs-schemes.c-1591-\nmm/damon/sysfs-schemes.c:1592:static struct attribute *damos_sysfs_quota_goals_attrs[] = {\nmm/damon/sysfs-schemes.c:1593:\t\u0026damos_sysfs_quota_goals_nr_attr.attr,\nmm/damon/sysfs-schemes.c-1594-\tNULL,\nmm/damon/sysfs-schemes.c-1595-};\nmm/damon/sysfs-schemes.c:1596:ATTRIBUTE_GROUPS(damos_sysfs_quota_goals);\nmm/damon/sysfs-schemes.c-1597-\nmm/damon/sysfs-schemes.c:1598:static const struct kobj_type damos_sysfs_quota_goals_ktype = {\nmm/damon/sysfs-schemes.c:1599:\t.release = damos_sysfs_quota_goals_release,\nmm/damon/sysfs-schemes.c-1600-\t.sysfs_ops = \u0026kobj_sysfs_ops,\nmm/damon/sysfs-schemes.c:1601:\t.default_groups = damos_sysfs_quota_goals_groups,\nmm/damon/sysfs-schemes.c-1602-};\n--\nmm/damon/sysfs-schemes.c=1718=struct damon_sysfs_quotas {\n--\nmm/damon/sysfs-schemes.c-1720-\tstruct damon_sysfs_weights *weights;\nmm/damon/sysfs-schemes.c:1721:\tstruct damos_sysfs_quota_goals *goals;\nmm/damon/sysfs-schemes.c-1722-\tunsigned long ms;\n--\nmm/damon/sysfs-schemes.c=1736=static int damon_sysfs_quotas_add_dirs(struct damon_sysfs_quotas *quotas)\n--\nmm/damon/sysfs-schemes.c-1738-\tstruct damon_sysfs_weights *weights;\nmm/damon/sysfs-schemes.c:1739:\tstruct damos_sysfs_quota_goals *goals;\nmm/damon/sysfs-schemes.c-1740-\tint err;\n--\nmm/damon/sysfs-schemes.c-1753-\nmm/damon/sysfs-schemes.c:1754:\tgoals = damos_sysfs_quota_goals_alloc();\nmm/damon/sysfs-schemes.c-1755-\tif (!goals) {\n--\nmm/damon/sysfs-schemes.c-1759-\terr = kobject_init_and_add(\u0026goals-\u003ekobj,\nmm/damon/sysfs-schemes.c:1760:\t\t\t\u0026damos_sysfs_quota_goals_ktype, \u0026quotas-\u003ekobj,\nmm/damon/sysfs-schemes.c-1761-\t\t\t\"goals\");\n--\nmm/damon/sysfs-schemes.c=1772=static void damon_sysfs_quotas_rm_dirs(struct damon_sysfs_quotas *quotas)\n--\nmm/damon/sysfs-schemes.c-1774-\tkobject_put(\u0026quotas-\u003eweights-\u003ekobj);\nmm/damon/sysfs-schemes.c:1775:\tdamos_sysfs_quota_goals_rm_dirs(quotas-\u003egoals);\nmm/damon/sysfs-schemes.c-1776-\tkobject_put(\u0026quotas-\u003egoals-\u003ekobj);\n--\nmm/damon/sysfs-schemes.c=2887=static int damos_sysfs_add_quota_score(\nmm/damon/sysfs-schemes.c:2888:\t\tstruct damos_sysfs_quota_goals *sysfs_goals,\nmm/damon/sysfs-schemes.c-2889-\t\tstruct damos_quota *quota)\n--\nmm/damon/sysfs-schemes.c-2894-\tfor (i = 0; i \u003c sysfs_goals-\u003enr; i++) {\nmm/damon/sysfs-schemes.c:2895:\t\tstruct damos_sysfs_quota_goal *sysfs_goal =\nmm/damon/sysfs-schemes.c-2896-\t\t\tsysfs_goals-\u003egoals_arr[i];\n"
} |
| 35/3 | 2026/09/20 20:11 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 14971 output: 33 thoughts: 28 Thoughts: Here's my take on those thoughts, tailored for an expert audience: **Examining `damos_new_quota_goal` in `mm/damon/core.c`** Okay, so we're looking at quota goal adjustments within the DAMON context. I need to make sure I understand how this new quota goal, `damos_new_quota_goal`, is being handled at the core level. Specifically, I want to drill into `mm/damon/core.c`. This suggests a potentially critical function or data structure resides there that might be responsible for setting or reacting to these quota changes. Is it a function handling the quota calculation? Is it where the monitoring actually happens? I need to understand how these quota updates percolate through the system. I'll need to pay close attention to the interactions between the DAMON core and other potentially relevant subsystems. My focus will be on the implications for overall memory management efficiency and stability. I should also see if there are any potential race conditions or edge cases related to these updates, especially if there's concurrent access to the quota data. This is an important piece to understand when evaluating the overall impact of the quota implementation. |
| 36/3 | 2026/09/20 20:11 | tool | grepper |
0mArgs:{
"Expression": "damos_new_quota_goal",
"PathPrefix": "mm/damon/"
}Results: {
"Output": "mm/damon/core.c=687=void damos_destroy_filter(struct damos_filter *f)\n--\nmm/damon/core.c-692-\nmm/damon/core.c:693:struct damos_quota_goal *damos_new_quota_goal(\nmm/damon/core.c-694-\t\tenum damos_quota_goal_metric metric, bool complement,\n--\nmm/damon/core.c=1248=int damos_commit_quota_goals(struct damos_quota *dst, struct damos_quota *src)\n--\nmm/damon/core.c-1265-\t\t\tcontinue;\nmm/damon/core.c:1266:\t\tnew_goal = damos_new_quota_goal(src_goal-\u003emetric, false,\nmm/damon/core.c-1267-\t\t\t\tsrc_goal-\u003etarget_value);\n--\nmm/damon/lru_sort.c=229=static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,\n--\nmm/damon/lru_sort.c-235-\t\treturn 0;\nmm/damon/lru_sort.c:236:\tgoal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, false,\nmm/damon/lru_sort.c-237-\t\t\tactive_mem_bp);\n--\nmm/damon/lru_sort.c-241-\t/* aim 0.2 % goal conflict, to keep little ping pong */\nmm/damon/lru_sort.c:242:\tgoal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP, false,\nmm/damon/lru_sort.c-243-\t\t\t10000 - active_mem_bp + 2);\n--\nmm/damon/reclaim.c=194=static int damon_reclaim_apply_parameters(void)\n--\nmm/damon/reclaim.c-235-\tif (quota_mem_pressure_us) {\nmm/damon/reclaim.c:236:\t\tgoal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US, false,\nmm/damon/reclaim.c-237-\t\t\t\tquota_mem_pressure_us);\n--\nmm/damon/reclaim.c-243-\tif (quota_autotune_feedback) {\nmm/damon/reclaim.c:244:\t\tgoal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, false,\nmm/damon/reclaim.c-245-\t\t\t\t10000);\n--\nmm/damon/sysfs-schemes.c=2887=static int damos_sysfs_add_quota_score(\n--\nmm/damon/sysfs-schemes.c-2900-\nmm/damon/sysfs-schemes.c:2901:\t\tgoal = damos_new_quota_goal(sysfs_goal-\u003emetric,\nmm/damon/sysfs-schemes.c-2902-\t\t\t\tsysfs_goal-\u003ecomplement,\n--\nmm/damon/tests/core-kunit.h=915=static void damos_test_commit_quota_goals_for(struct kunit *test,\n--\nmm/damon/tests/core-kunit.h-933-\t\t */\nmm/damon/tests/core-kunit.h:934:\t\tgoal = damos_new_quota_goal(dst_goals[i].metric, false,\nmm/damon/tests/core-kunit.h-935-\t\t\t\tdst_goals[i].target_value);\n"
} |
| 37/3 | 2026/09/20 20:11 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 16226 output: 36 thoughts: 26 Thoughts: Here's my take on the thought process, as if it were my own: **Investigating the New Quota Goal in DAMON** Okay, so I need to understand how the new quota goal is defined within DAMON. My first step is clear: I need to dive into the `mm/damon/core.c` file and specifically locate the `damos_new_quota_goal` definition. This is where the core logic of the quota management within DAMON likely resides. I'm expecting to find the underlying mechanisms and parameters that dictate how this new goal is established and enforced. From here, I will begin to understand how to tune and calibrate. |
| 38/3 | 2026/09/20 20:11 | tool | read-file |
0mArgs:{
"File": "mm/damon/core.c",
"FirstLine": 692,
"LineCount": 30
}Results: {
"Contents": " 692:\t\n 693:\tstruct damos_quota_goal *damos_new_quota_goal(\n 694:\t\t\tenum damos_quota_goal_metric metric, bool complement,\n 695:\t\t\tunsigned long target_value)\n 696:\t{\n 697:\t\tstruct damos_quota_goal *goal;\n 698:\t\n 699:\t\tgoal = kmalloc_obj(*goal);\n 700:\t\tif (!goal)\n 701:\t\t\treturn NULL;\n 702:\t\tgoal-\u003emetric = metric;\n 703:\t\tgoal-\u003ecomplement = complement;\n 704:\t\tgoal-\u003etarget_value = target_value;\n 705:\t\tif (metric == DAMOS_QUOTA_SOME_MEM_PSI_US)\n 706:\t\t\tgoal-\u003elast_psi_total = U64_MAX;\n 707:\t\tINIT_LIST_HEAD(\u0026goal-\u003elist);\n 708:\t\treturn goal;\n 709:\t}\n 710:\t\n 711:\tvoid damos_add_quota_goal(struct damos_quota *q, struct damos_quota_goal *g)\n 712:\t{\n 713:\t\tlist_add_tail(\u0026g-\u003elist, \u0026q-\u003egoals);\n 714:\t}\n 715:\t\n 716:\tstatic void damos_del_quota_goal(struct damos_quota_goal *g)\n 717:\t{\n 718:\t\tlist_del(\u0026g-\u003elist);\n 719:\t}\n 720:\t\n 721:\tstatic void damos_free_quota_goal(struct damos_quota_goal *g)\n"
} |
| 39/3 | 2026/09/20 20:11 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 16871 output: 36 thoughts: 87 Thoughts: **A DAMON Core Oversight** Hold on a second! I need to double-check something. My gut is telling me there's an issue... specifically, let me zoom in on line 699 of `mm/damon/core.c`. Ah ha! Here it is: `goal = kmalloc_obj(*goal);`. Okay, now, hold on a second! Why are we using `kmalloc_obj` here, NOT `kzalloc_obj`?! I need to investigate this further. I need to make sure that the memory is initialized correctly. Alright, time to crack this open. Let me examine the `struct damos_quota_goal` definition and *all* the fields within that structure. I need to ensure that uninitialized memory is not at play here. This could lead to a very subtle but nasty bug. Okay, let's also read `include/linux/damon.h` and check the relevant struct there, to make sure everything's consistent! |
| 40/3 | 2026/09/20 20:11 | tool | read-file |
0mArgs:{
"File": "include/linux/damon.h",
"FirstLine": 190,
"LineCount": 40
}Results: {
"Contents": " 190:\t * entered by the user, probably inside the kdamond callbacks. Otherwise,\n 191:\t * DAMON sets @current_value with self-measured value of @metric.\n 192:\t *\n 193:\t * If @metric is DAMOS_QUOTA_NODE_MEM_{USED,FREE}_BP, @nid represents the node\n 194:\t * id of the target node to account the used/free memory.\n 195:\t *\n 196:\t * If @metric is DAMOS_QUOTA_NODE_MEMCG_{USED,FREE}_BP, @nid and @memcg_id\n 197:\t * represents the node id and the cgroup to account the used memory for.\n 198:\t */\n 199:\tstruct damos_quota_goal {\n 200:\t\tenum damos_quota_goal_metric metric;\n 201:\t\tbool complement;\n 202:\t\tunsigned long target_value;\n 203:\t\tunsigned long current_value;\n 204:\t\t/* metric-dependent fields */\n 205:\t\tunion {\n 206:\t\t\tstruct {\n 207:\t\t\t\tint nid;\n 208:\t\t\t\tu64 memcg_id;\n 209:\t\t\t};\n 210:\t/* private: */\n 211:\t\t\t/* Last measured total PSI */\n 212:\t\t\tu64 last_psi_total;\n 213:\t\n 214:\t\t};\n 215:\t/* private: */\n 216:\t\t/* List head for siblings. */\n 217:\t\tstruct list_head list;\n 218:\t};\n 219:\t\n 220:\t/**\n 221:\t * enum damos_quota_goal_tuner - Goal-based quota tuning logic.\n 222:\t * @DAMOS_QUOTA_GOAL_TUNER_CONSIST:\tAim long term consistent quota.\n 223:\t * @DAMOS_QUOTA_GOAL_TUNER_TEMPORAL:\tAim zero quota asap.\n 224:\t */\n 225:\tenum damos_quota_goal_tuner {\n 226:\t\tDAMOS_QUOTA_GOAL_TUNER_CONSIST,\n 227:\t\tDAMOS_QUOTA_GOAL_TUNER_TEMPORAL,\n 228:\t};\n 229:\t\n"
} |
| 41/3 | 2026/09/20 20:11 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 17824 output: 37 thoughts: 366 Thoughts: **Analyzing the `damos_new_quota_goal` Function**
Okay, hold on a second. Let me take a closer look at this `damos_new_quota_goal` function. Specifically, let's see how this new quota goal is being constructed. I see the code is:
```c
struct damos_quota_goal *damos_new_quota_goal(
enum damos_quota_goal_metric metric, bool complement,
unsigned long target_value)
{
struct damos_quota_goal *goal;
goal = kmalloc_obj(*goal);
if (!goal)
return NULL;
goal->metric = metric;
goal->complement = complement;
goal->target_value = target_value;
if (metric == DAMOS_QUOTA_SOME_MEM_PSI_US)
goal->last_psi_total = U64_MAX;
INIT_LIST_HEAD(&goal->list);
return goal;
}
```
My initial thought is to immediately zoom in on what happens to certain critical fields within the `struct damos_quota_goal`. Specifically, where does `goal->current_value` get its value? And what about `goal->nid` or `goal->memcg_id`? Are they being initialized here? Or somewhere else? Are they left uninitialized? That could be a problem, so I need to know.
Okay, wait, what exactly did the patch change? Let me scroll back... Ah, here it is:
```c
struct damos_quota_goal *damos_new_quota_goal(
- enum damos_quota_goal_metric metric,
+ enum damos_quota_goal_metric metric, bool complement,
unsigned long target_value)
{
...
+ goal->complement = complement;
```
Right, it added the `complement` parameter and assigned it to `goal->complement`. Good. At least *that* field is being initialized now. But what about the other fields I was concerned with? I better check how `damos_set_quota_goal_current_value` works, as it's the most likely place these other fields will be set. I need to be sure.
|
| 42/3 | 2026/09/20 20:11 | tool | read-file |
0mArgs:{
"File": "mm/damon/core.c",
"FirstLine": 3200,
"LineCount": 60
}Results: {
"Contents": "3200:\t\n3201:\tstatic void damos_set_quota_goal_current_value(struct damon_ctx *c,\n3202:\t\t\tstruct damos *s, struct damos_quota_goal *goal)\n3203:\t{\n3204:\t\tu64 now_psi_total;\n3205:\t\n3206:\t\tswitch (goal-\u003emetric) {\n3207:\t\tcase DAMOS_QUOTA_USER_INPUT:\n3208:\t\t\t/* User should already set goal-\u003ecurrent_value */\n3209:\t\t\tbreak;\n3210:\t\tcase DAMOS_QUOTA_SOME_MEM_PSI_US:\n3211:\t\t\tnow_psi_total = damos_get_some_mem_psi_total();\n3212:\t\t\t/* uninitialized last_psi_total; make no effect this round */\n3213:\t\t\tif (goal-\u003elast_psi_total == U64_MAX)\n3214:\t\t\t\tgoal-\u003ecurrent_value = goal-\u003etarget_value;\n3215:\t\t\telse\n3216:\t\t\t\tgoal-\u003ecurrent_value = now_psi_total -\n3217:\t\t\t\t\tgoal-\u003elast_psi_total;\n3218:\t\t\tgoal-\u003elast_psi_total = now_psi_total;\n3219:\t\t\tbreak;\n3220:\t\tcase DAMOS_QUOTA_NODE_MEM_USED_BP:\n3221:\t\tcase DAMOS_QUOTA_NODE_MEM_FREE_BP:\n3222:\t\t\tgoal-\u003ecurrent_value = damos_get_node_mem_bp(goal);\n3223:\t\t\tbreak;\n3224:\t\tcase DAMOS_QUOTA_NODE_MEMCG_USED_BP:\n3225:\t\tcase DAMOS_QUOTA_NODE_MEMCG_FREE_BP:\n3226:\t\t\tgoal-\u003ecurrent_value = damos_get_node_memcg_used_bp(goal);\n3227:\t\t\tbreak;\n3228:\t\tcase DAMOS_QUOTA_ACTIVE_MEM_BP:\n3229:\t\tcase DAMOS_QUOTA_INACTIVE_MEM_BP:\n3230:\t\t\tgoal-\u003ecurrent_value = damos_get_in_active_mem_bp(\n3231:\t\t\t\t\tgoal-\u003emetric == DAMOS_QUOTA_ACTIVE_MEM_BP);\n3232:\t\t\tbreak;\n3233:\t\tcase DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP:\n3234:\t\t\tgoal-\u003ecurrent_value = damos_get_node_eligible_mem_bp(c, s,\n3235:\t\t\t\t\tgoal-\u003enid);\n3236:\t\t\tbreak;\n3237:\t\tcase DAMOS_QUOTA_HUGEPAGE_MEM_BP:\n3238:\t\t\tgoal-\u003ecurrent_value = damos_hugepage_mem_bp();\n3239:\t\t\tbreak;\n3240:\t\tdefault:\n3241:\t\t\tbreak;\n3242:\t\t}\n3243:\t\tif (!goal-\u003ecomplement)\n3244:\t\t\treturn;\n3245:\t\n3246:\t\t/* updte current_value to complemented value */\n3247:\t\n3248:\t\t/* for user_input, users set complemented value on their own */\n3249:\t\tif (goal-\u003emetric == DAMOS_QUOTA_USER_INPUT)\n3250:\t\t\treturn;\n3251:\t\tif (goal-\u003emetric == DAMOS_QUOTA_SOME_MEM_PSI_US)\n3252:\t\t\tgoal-\u003ecurrent_value = s-\u003equota.reset_interval * 1000 -\n3253:\t\t\t\tgoal-\u003ecurrent_value;\n3254:\t\telse\n3255:\t\t\tgoal-\u003ecurrent_value = 10000 - goal-\u003ecurrent_value;\n3256:\t}\n3257:\t\n3258:\t/* Return the highest score since it makes schemes least aggressive */\n3259:\tstatic unsigned long damos_quota_score(struct damon_ctx *c, struct damos *s)\n"
} |
| 43/3 | 2026/09/20 20:11 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 19745 output: 37 thoughts: 40 Thoughts: Okay, let's dive into this. I need to refresh my memory on how `damos_commit_quota_goals` actually functions. I'll head straight to the source. Specifically, I need to understand lines 1220 through 1280 within the `mm/damon/core.c` file. That section holds the key to how it all operates, and I want a clear picture of its implementation details. Time to get down to the nitty-gritty. |
| 44/3 | 2026/09/20 20:11 | tool | read-file |
0mArgs:{
"File": "mm/damon/core.c",
"FirstLine": 1220,
"LineCount": 60
}Results: {
"Contents": "1220:\t}\n1221:\t\n1222:\tstatic int damos_commit_quota_goal(\n1223:\t\t\tstruct damos_quota_goal *dst, struct damos_quota_goal *src)\n1224:\t{\n1225:\t\tif (!src-\u003etarget_value)\n1226:\t\t\treturn -EINVAL;\n1227:\t\tdst-\u003emetric = src-\u003emetric;\n1228:\t\tdst-\u003ecomplement = src-\u003ecomplement;\n1229:\t\tdst-\u003etarget_value = src-\u003etarget_value;\n1230:\t\tif (dst-\u003emetric == DAMOS_QUOTA_USER_INPUT)\n1231:\t\t\tdst-\u003ecurrent_value = src-\u003ecurrent_value;\n1232:\t\tdamos_commit_quota_goal_union(dst, src);\n1233:\t\treturn 0;\n1234:\t}\n1235:\t\n1236:\t/**\n1237:\t * damos_commit_quota_goals() - Commit DAMOS quota goals to another quota.\n1238:\t * @dst:\tThe commit destination DAMOS quota.\n1239:\t * @src:\tThe commit source DAMOS quota.\n1240:\t *\n1241:\t * Copies user-specified parameters for quota goals from @src to @dst. Users\n1242:\t * should use this function for quota goals-level parameters update of running\n1243:\t * DAMON contexts, instead of manual in-place updates.\n1244:\t *\n1245:\t * This function should be called from parameters-update safe context, like\n1246:\t * damon_call().\n1247:\t */\n1248:\tint damos_commit_quota_goals(struct damos_quota *dst, struct damos_quota *src)\n1249:\t{\n1250:\t\tstruct damos_quota_goal *dst_goal, *next, *src_goal, *new_goal;\n1251:\t\tint i = 0, j = 0, err;\n1252:\t\n1253:\t\tdamos_for_each_quota_goal_safe(dst_goal, next, dst) {\n1254:\t\t\tsrc_goal = damos_nth_quota_goal(i++, src);\n1255:\t\t\tif (src_goal) {\n1256:\t\t\t\terr = damos_commit_quota_goal(dst_goal, src_goal);\n1257:\t\t\t\tif (err)\n1258:\t\t\t\t\treturn err;\n1259:\t\t\t} else {\n1260:\t\t\t\tdamos_destroy_quota_goal(dst_goal);\n1261:\t\t\t}\n1262:\t\t}\n1263:\t\tdamos_for_each_quota_goal_safe(src_goal, next, src) {\n1264:\t\t\tif (j++ \u003c i)\n1265:\t\t\t\tcontinue;\n1266:\t\t\tnew_goal = damos_new_quota_goal(src_goal-\u003emetric, false,\n1267:\t\t\t\t\tsrc_goal-\u003etarget_value);\n1268:\t\t\tif (!new_goal)\n1269:\t\t\t\treturn -ENOMEM;\n1270:\t\t\terr = damos_commit_quota_goal(new_goal, src_goal);\n1271:\t\t\tif (err) {\n1272:\t\t\t\tdamos_free_quota_goal(new_goal);\n1273:\t\t\t\treturn err;\n1274:\t\t\t}\n1275:\t\t\tdamos_add_quota_goal(dst, new_goal);\n1276:\t\t}\n1277:\t\treturn 0;\n1278:\t}\n1279:\t\n"
} |
| 45/3 | 2026/09/20 20:11 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 20874 output: 20 thoughts: 359 Thoughts: **Analyzing DAMOS Quota Goal Implementation** Okay, let's break this down. I'm seeing a potential area of concern within the DAMOS quota goal handling, specifically related to the `complement` flag. The first thing that jumps out is the sequence in `damos_commit_quota_goals`. I see a new goal being created: `new_goal = damos_new_quota_goal(...)` and then immediately, the newly created goal is committed: `err = damos_commit_quota_goal(new_goal, src_goal)`. Now, the commit operation seems to be where the `dst->complement = src->complement;` assignment takes place. This is interesting, because `damos_sysfs_quota_goal` uses `kzalloc_obj`, which defaults `complement` to `false`. So, from what I'm seeing, `complement` is initialized to false, gets set from sysfs, and then ultimately gets copied in the commit function. The sysfs interface reads and writes `complement` as 'Y' or 'N' using `kstrtobool` and `sysfs_emit`. The issue is, how is it getting set? I see in `damos_sysfs_add_quota_score`, that the sysfs value is passed directly as a parameter. `goal = damos_new_quota_goal(sysfs_goal->metric, sysfs_goal->complement, sysfs_goal->target_value);` which is good, that's what I would expect. However, what else is setting or using `damos_new_quota_goal` or accessing `complement`? I need to look for other uses of `damos_quota_goal`, and `complement` in the repository to make sure this is the only way it's being used. |
| 46/3 | 2026/09/20 20:11 | tool | grepper |
0mArgs:{
"Expression": "damos_quota_goal"
}Results: {
"Output": "include/linux/damon.h=128=enum damos_action {\n--\ninclude/linux/damon.h-143-/**\ninclude/linux/damon.h:144: * enum damos_quota_goal_metric - Represents the metric to be used as the goal\ninclude/linux/damon.h-145- *\n--\ninclude/linux/damon.h-160- */\ninclude/linux/damon.h:161:enum damos_quota_goal_metric {\ninclude/linux/damon.h-162-\tDAMOS_QUOTA_USER_INPUT,\n--\ninclude/linux/damon.h-175-/**\ninclude/linux/damon.h:176: * struct damos_quota_goal - DAMOS scheme quota auto-tuning goal.\ninclude/linux/damon.h-177- * @metric:\t\tMetric to be used for representing the goal.\n--\ninclude/linux/damon.h-198- */\ninclude/linux/damon.h:199:struct damos_quota_goal {\ninclude/linux/damon.h:200:\tenum damos_quota_goal_metric metric;\ninclude/linux/damon.h-201-\tbool complement;\n--\ninclude/linux/damon.h-220-/**\ninclude/linux/damon.h:221: * enum damos_quota_goal_tuner - Goal-based quota tuning logic.\ninclude/linux/damon.h-222- * @DAMOS_QUOTA_GOAL_TUNER_CONSIST:\tAim long term consistent quota.\n--\ninclude/linux/damon.h-224- */\ninclude/linux/damon.h:225:enum damos_quota_goal_tuner {\ninclude/linux/damon.h-226-\tDAMOS_QUOTA_GOAL_TUNER_CONSIST,\n--\ninclude/linux/damon.h=278=struct damos_quota {\n--\ninclude/linux/damon.h-282-\ninclude/linux/damon.h:283:\tenum damos_quota_goal_tuner goal_tuner;\ninclude/linux/damon.h-284-\tunsigned long esz;\n--\ninclude/linux/damon.h-293-/* private: */\ninclude/linux/damon.h:294:\t/* Head of quota tuning goals (\u0026damos_quota_goal) list. */\ninclude/linux/damon.h-295-\tstruct list_head goals;\n--\ninclude/linux/damon.h=1097=void damos_destroy_filter(struct damos_filter *f);\ninclude/linux/damon.h-1098-\ninclude/linux/damon.h:1099:struct damos_quota_goal *damos_new_quota_goal(\ninclude/linux/damon.h:1100:\t\tenum damos_quota_goal_metric metric, bool complement,\ninclude/linux/damon.h-1101-\t\tunsigned long target_value);\ninclude/linux/damon.h:1102:void damos_add_quota_goal(struct damos_quota *q, struct damos_quota_goal *g);\ninclude/linux/damon.h:1103:void damos_destroy_quota_goal(struct damos_quota_goal *goal);\ninclude/linux/damon.h-1104-\n--\nmm/damon/core.c=687=void damos_destroy_filter(struct damos_filter *f)\n--\nmm/damon/core.c-692-\nmm/damon/core.c:693:struct damos_quota_goal *damos_new_quota_goal(\nmm/damon/core.c:694:\t\tenum damos_quota_goal_metric metric, bool complement,\nmm/damon/core.c-695-\t\tunsigned long target_value)\nmm/damon/core.c-696-{\nmm/damon/core.c:697:\tstruct damos_quota_goal *goal;\nmm/damon/core.c-698-\n--\nmm/damon/core.c-710-\nmm/damon/core.c:711:void damos_add_quota_goal(struct damos_quota *q, struct damos_quota_goal *g)\nmm/damon/core.c-712-{\n--\nmm/damon/core.c-715-\nmm/damon/core.c:716:static void damos_del_quota_goal(struct damos_quota_goal *g)\nmm/damon/core.c-717-{\n--\nmm/damon/core.c-720-\nmm/damon/core.c:721:static void damos_free_quota_goal(struct damos_quota_goal *g)\nmm/damon/core.c-722-{\n--\nmm/damon/core.c-725-\nmm/damon/core.c:726:void damos_destroy_quota_goal(struct damos_quota_goal *g)\nmm/damon/core.c-727-{\n--\nmm/damon/core.c-731-\nmm/damon/core.c:732:static bool damos_quota_goals_empty(struct damos_quota *q)\nmm/damon/core.c-733-{\n--\nmm/damon/core.c=820=void damon_destroy_scheme(struct damos *s)\nmm/damon/core.c-821-{\nmm/damon/core.c:822:\tstruct damos_quota_goal *g, *g_next;\nmm/damon/core.c-823-\tstruct damos_filter *f, *next;\n--\nmm/damon/core.c=1173=void damon_set_schemes(struct damon_ctx *ctx, struct damos **schemes,\n--\nmm/damon/core.c-1184-\nmm/damon/core.c:1185:static struct damos_quota_goal *damos_nth_quota_goal(\nmm/damon/core.c-1186-\t\tint n, struct damos_quota *q)\nmm/damon/core.c-1187-{\nmm/damon/core.c:1188:\tstruct damos_quota_goal *goal;\nmm/damon/core.c-1189-\tint i = 0;\n--\nmm/damon/core.c=1198=static void damos_commit_quota_goal_union(\nmm/damon/core.c:1199:\t\tstruct damos_quota_goal *dst, struct damos_quota_goal *src)\nmm/damon/core.c-1200-{\n--\nmm/damon/core.c=1222=static int damos_commit_quota_goal(\nmm/damon/core.c:1223:\t\tstruct damos_quota_goal *dst, struct damos_quota_goal *src)\nmm/damon/core.c-1224-{\n--\nmm/damon/core.c=1248=int damos_commit_quota_goals(struct damos_quota *dst, struct damos_quota *src)\nmm/damon/core.c-1249-{\nmm/damon/core.c:1250:\tstruct damos_quota_goal *dst_goal, *next, *src_goal, *new_goal;\nmm/damon/core.c-1251-\tint i = 0, j = 0, err;\n--\nmm/damon/core.c=1930=static int __damon_commit_ctx(struct damon_ctx *dst, struct damon_ctx *src)\n--\nmm/damon/core.c-1933-\tstruct damos *scheme;\nmm/damon/core.c:1934:\tstruct damos_quota_goal *goal;\nmm/damon/core.c-1935-\n--\nmm/damon/core.c=2457=static bool damos_quota_is_set(struct damos_quota *quota)\n--\nmm/damon/core.c-2459-\treturn quota-\u003eesz || quota-\u003esz || quota-\u003ems ||\nmm/damon/core.c:2460:\t\t!damos_quota_goals_empty(quota);\nmm/damon/core.c-2461-}\n--\nmm/damon/core.c=2966=static __kernel_ulong_t damos_get_node_mem_bp(\nmm/damon/core.c:2967:\t\tstruct damos_quota_goal *goal)\nmm/damon/core.c-2968-{\n--\nmm/damon/core.c=2994=static unsigned long damos_get_node_memcg_used_bp(\nmm/damon/core.c:2995:\t\tstruct damos_quota_goal *goal)\nmm/damon/core.c-2996-{\n--\nmm/damon/core.c=3148=static __kernel_ulong_t damos_get_node_mem_bp(\nmm/damon/core.c:3149:\t\tstruct damos_quota_goal *goal)\nmm/damon/core.c-3150-{\n--\nmm/damon/core.c=3154=static unsigned long damos_get_node_memcg_used_bp(\nmm/damon/core.c:3155:\t\tstruct damos_quota_goal *goal)\nmm/damon/core.c-3156-{\n--\nmm/damon/core.c=3201=static void damos_set_quota_goal_current_value(struct damon_ctx *c,\nmm/damon/core.c:3202:\t\tstruct damos *s, struct damos_quota_goal *goal)\nmm/damon/core.c-3203-{\n--\nmm/damon/core.c=3259=static unsigned long damos_quota_score(struct damon_ctx *c, struct damos *s)\nmm/damon/core.c-3260-{\nmm/damon/core.c:3261:\tstruct damos_quota_goal *goal;\nmm/damon/core.c-3262-\tstruct damos_quota *quota = \u0026s-\u003equota;\n--\nmm/damon/lru_sort.c=229=static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,\n--\nmm/damon/lru_sort.c-231-{\nmm/damon/lru_sort.c:232:\tstruct damos_quota_goal *goal;\nmm/damon/lru_sort.c-233-\n--\nmm/damon/reclaim.c=194=static int damon_reclaim_apply_parameters(void)\n--\nmm/damon/reclaim.c-199-\tstruct damos *scheme;\nmm/damon/reclaim.c:200:\tstruct damos_quota_goal *goal;\nmm/damon/reclaim.c-201-\tstruct damos_filter *filter;\n--\nmm/damon/sysfs-schemes.c=1220=struct damos_sysfs_quota_goal {\nmm/damon/sysfs-schemes.c-1221-\tstruct kobject kobj;\nmm/damon/sysfs-schemes.c:1222:\tenum damos_quota_goal_metric metric;\nmm/damon/sysfs-schemes.c-1223-\tbool complement;\n--\nmm/damon/sysfs-schemes.c=1235=struct damos_sysfs_qgoal_metric_name {\nmm/damon/sysfs-schemes.c:1236:\tenum damos_quota_goal_metric metric;\nmm/damon/sysfs-schemes.c-1237-\tchar *name;\n--\nmm/damon/sysfs-schemes.c=1718=struct damon_sysfs_quotas {\n--\nmm/damon/sysfs-schemes.c-1725-\tunsigned long effective_sz;\t/* Effective size quota in bytes */\nmm/damon/sysfs-schemes.c:1726:\tenum damos_quota_goal_tuner goal_tuner;\nmm/damon/sysfs-schemes.c-1727-\tunsigned int fail_charge_num;\n--\nmm/damon/sysfs-schemes.c=1851=struct damos_sysfs_qgoal_tuner_name {\nmm/damon/sysfs-schemes.c:1852:\tenum damos_quota_goal_tuner tuner;\nmm/damon/sysfs-schemes.c-1853-\tchar *name;\n--\nmm/damon/sysfs-schemes.c=2887=static int damos_sysfs_add_quota_score(\n--\nmm/damon/sysfs-schemes.c-2890-{\nmm/damon/sysfs-schemes.c:2891:\tstruct damos_quota_goal *goal;\nmm/damon/sysfs-schemes.c-2892-\tint i, err;\n--\nmm/damon/sysfs-schemes.c=2935=int damos_sysfs_set_quota_scores(struct damon_sysfs_schemes *sysfs_schemes,\n--\nmm/damon/sysfs-schemes.c-2944-\t\tstruct damon_sysfs_scheme *sysfs_scheme;\nmm/damon/sysfs-schemes.c:2945:\t\tstruct damos_quota_goal *g, *g_next;\nmm/damon/sysfs-schemes.c-2946-\t\tint err;\n--\nmm/damon/tests/core-kunit.h=815=static void damos_test_commit_quota_goal_for(struct kunit *test,\nmm/damon/tests/core-kunit.h:816:\t\tstruct damos_quota_goal *dst,\nmm/damon/tests/core-kunit.h:817:\t\tstruct damos_quota_goal *src)\nmm/damon/tests/core-kunit.h-818-{\n--\nmm/damon/tests/core-kunit.h=847=static void damos_test_commit_quota_goal(struct kunit *test)\nmm/damon/tests/core-kunit.h-848-{\nmm/damon/tests/core-kunit.h:849:\tstruct damos_quota_goal dst = {\nmm/damon/tests/core-kunit.h-850-\t\t.metric = DAMOS_QUOTA_SOME_MEM_PSI_US,\n--\nmm/damon/tests/core-kunit.h-856-\tdamos_test_commit_quota_goal_for(test, \u0026dst,\nmm/damon/tests/core-kunit.h:857:\t\t\t\u0026(struct damos_quota_goal) {\nmm/damon/tests/core-kunit.h-858-\t\t\t.metric = DAMOS_QUOTA_SOME_MEM_PSI_US,\n--\nmm/damon/tests/core-kunit.h-863-\tdamos_test_commit_quota_goal_for(test, \u0026dst,\nmm/damon/tests/core-kunit.h:864:\t\t\t\u0026(struct damos_quota_goal){\nmm/damon/tests/core-kunit.h-865-\t\t\t.metric = DAMOS_QUOTA_USER_INPUT,\n--\nmm/damon/tests/core-kunit.h-869-\tdamos_test_commit_quota_goal_for(test, \u0026dst,\nmm/damon/tests/core-kunit.h:870:\t\t\t\u0026(struct damos_quota_goal){\nmm/damon/tests/core-kunit.h-871-\t\t\t.metric = DAMOS_QUOTA_NODE_MEM_FREE_BP,\n--\nmm/damon/tests/core-kunit.h-876-\tdamos_test_commit_quota_goal_for(test, \u0026dst,\nmm/damon/tests/core-kunit.h:877:\t\t\t\u0026(struct damos_quota_goal){\nmm/damon/tests/core-kunit.h-878-\t\t\t.metric = DAMOS_QUOTA_NODE_MEM_USED_BP,\n--\nmm/damon/tests/core-kunit.h-883-\tdamos_test_commit_quota_goal_for(test, \u0026dst,\nmm/damon/tests/core-kunit.h:884:\t\t\t\u0026(struct damos_quota_goal){\nmm/damon/tests/core-kunit.h-885-\t\t\t.metric = DAMOS_QUOTA_NODE_MEMCG_USED_BP,\n--\nmm/damon/tests/core-kunit.h-891-\tdamos_test_commit_quota_goal_for(test, \u0026dst,\nmm/damon/tests/core-kunit.h:892:\t\t\t\u0026(struct damos_quota_goal){\nmm/damon/tests/core-kunit.h-893-\t\t\t.metric = DAMOS_QUOTA_NODE_MEMCG_FREE_BP,\n--\nmm/damon/tests/core-kunit.h-899-\tdamos_test_commit_quota_goal_for(test, \u0026dst,\nmm/damon/tests/core-kunit.h:900:\t\t\t\u0026(struct damos_quota_goal) {\nmm/damon/tests/core-kunit.h-901-\t\t\t.metric = DAMOS_QUOTA_SOME_MEM_PSI_US,\n--\nmm/damon/tests/core-kunit.h-906-\tdamos_test_commit_quota_goal_for(test, \u0026dst,\nmm/damon/tests/core-kunit.h:907:\t\t\t\u0026(struct damos_quota_goal){\nmm/damon/tests/core-kunit.h-908-\t\t\t.metric = DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP,\n--\nmm/damon/tests/core-kunit.h=915=static void damos_test_commit_quota_goals_for(struct kunit *test,\nmm/damon/tests/core-kunit.h:916:\t\tstruct damos_quota_goal *dst_goals, int nr_dst_goals,\nmm/damon/tests/core-kunit.h:917:\t\tstruct damos_quota_goal *src_goals, int nr_src_goals)\nmm/damon/tests/core-kunit.h-918-{\nmm/damon/tests/core-kunit.h-919-\tstruct damos_quota dst, src;\nmm/damon/tests/core-kunit.h:920:\tstruct damos_quota_goal *goal, *next;\nmm/damon/tests/core-kunit.h-921-\tbool skip = true;\n--\nmm/damon/tests/core-kunit.h=969=static void damos_test_commit_quota_goals(struct kunit *test)\n--\nmm/damon/tests/core-kunit.h-971-\tdamos_test_commit_quota_goals_for(test,\nmm/damon/tests/core-kunit.h:972:\t\t\t(struct damos_quota_goal[]){}, 0,\nmm/damon/tests/core-kunit.h:973:\t\t\t(struct damos_quota_goal[]){\nmm/damon/tests/core-kunit.h-974-\t\t\t\t{\n--\nmm/damon/tests/core-kunit.h-979-\tdamos_test_commit_quota_goals_for(test,\nmm/damon/tests/core-kunit.h:980:\t\t\t(struct damos_quota_goal[]){\nmm/damon/tests/core-kunit.h-981-\t\t\t\t{\n--\nmm/damon/tests/core-kunit.h-986-\t\t\t}, 1,\nmm/damon/tests/core-kunit.h:987:\t\t\t(struct damos_quota_goal[]){\nmm/damon/tests/core-kunit.h-988-\t\t\t\t{\n--\nmm/damon/tests/core-kunit.h-993-\tdamos_test_commit_quota_goals_for(test,\nmm/damon/tests/core-kunit.h:994:\t\t\t(struct damos_quota_goal[]){\nmm/damon/tests/core-kunit.h-995-\t\t\t\t{\n--\nmm/damon/tests/core-kunit.h-1000-\t\t\t}, 1,\nmm/damon/tests/core-kunit.h:1001:\t\t\t(struct damos_quota_goal[]){}, 0);\nmm/damon/tests/core-kunit.h-1002-}\n--\nsamples/damon/mtier.c=78=static struct damon_ctx *damon_sample_mtier_build_ctx(bool promote)\n--\nsamples/damon/mtier.c-83-\tstruct damos *scheme;\nsamples/damon/mtier.c:84:\tstruct damos_quota_goal *quota_goal;\nsamples/damon/mtier.c-85-\tstruct damos_filter *filter;\n--\ntools/testing/selftests/damon/Makefile=13=TEST_PROGS += sysfs_update_schemes_tried_regions_wss_estimation.py\ntools/testing/selftests/damon/Makefile:14:TEST_PROGS += damos_quota.py damos_quota_goal.py damos_apply_interval.py\ntools/testing/selftests/damon/Makefile-15-TEST_PROGS += damos_tried_regions.py damon_nr_regions.py\n--\ntools/testing/selftests/damon/drgn_dump_damon_status.py=114=def damos_access_pattern_to_dict(pattern):\n--\ntools/testing/selftests/damon/drgn_dump_damon_status.py-123-\ntools/testing/selftests/damon/drgn_dump_damon_status.py:124:def damos_quota_goal_to_dict(goal):\ntools/testing/selftests/damon/drgn_dump_damon_status.py-125- return to_dict(goal, [\n--\ntools/testing/selftests/damon/drgn_dump_damon_status.py-132-\ntools/testing/selftests/damon/drgn_dump_damon_status.py:133:def damos_quota_goals_to_list(goals):\ntools/testing/selftests/damon/drgn_dump_damon_status.py:134: return [damos_quota_goal_to_dict(g)\ntools/testing/selftests/damon/drgn_dump_damon_status.py-135- for g in list_for_each_entry(\ntools/testing/selftests/damon/drgn_dump_damon_status.py:136: 'struct damos_quota_goal', goals.address_of_(), 'list')]\ntools/testing/selftests/damon/drgn_dump_damon_status.py-137-\ntools/testing/selftests/damon/drgn_dump_damon_status.py=138=def damos_quota_to_dict(quota):\n--\ntools/testing/selftests/damon/drgn_dump_damon_status.py-141- ['ms', int], ['sz', int],\ntools/testing/selftests/damon/drgn_dump_damon_status.py:142: ['goals', damos_quota_goals_to_list],\ntools/testing/selftests/damon/drgn_dump_damon_status.py-143- ['goal_tuner', int],\n"
} |
| 47/3 | 2026/09/20 20:11 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 27667 output: 248 thoughts: 1116 Thoughts: **KMSAN Assessment: No Need for Dedicated Fuzzing**
Alright, let's break this down. I've reviewed the code changes carefully, focusing on potential uninitialized memory risks, and I'm confident in my assessment.
First, the patch introduces a `complement` boolean field into `damos_quota_goal` and `damos_sysfs_quota_goal`. This `complement` field is exposed via a sysfs attribute. The implementation updates the relevant structures and functions (`damos_new_quota_goal`, `damos_commit_quota_goal`, `damos_set_quota_goal_current_value`) to handle this new field. Critically, I've checked all allocations and uses of this field.
My analysis follows the KMSAN criteria rigorously. We need to look for cases where uninitialized memory could be read, especially:
1. **Kernel structures to userspace:** The sysfs attribute uses `sysfs_emit`, which formats a character ('Y' or 'N') based on `goal->complement` into a buffer. `goal->complement` itself is always initialized, either during allocation using `kzalloc_obj` or through explicit assignment in `damos_new_quota_goal()`. There's no raw structure copying to user space. No issue here.
2. **Conditional logic on uninitialized fields:** `goal->complement` is consistently initialized. I've tracked its initialization through all allocation paths – `damos_sysfs_quota_goal` via `kzalloc_obj` defaults to `false`, and `damos_quota_goal` is explicitly set via the constructor. So, no risk of a read of an uninitialized value.
3. **Complex data structures, uninitialized fields read later:** The `complement` field is explicitly initialized everywhere. I'm confident we're not dealing with any read issues from uninitialized memory.
4. **Bounds/Length issues:** The patch doesn't modify any buffer bounds. The arithmetic operation `10000 - goal->current_value` is safe since the `goal->current_value` is initialized.
Therefore, there are **no uninitialized memory risks** introduced by these changes. This means standard debuggers such as KASAN would catch any issues present (UAF, OOB, etc). KMSAN, specifically, deals with read of uninitialized memory. There's no need for a dedicated KMSAN fuzzing run. KMSAN would be superfluous here since the risk is effectively zero. The sysfs interaction is also straightforward, no chance of info leak.
I've contrasted KASAN and KMSAN. Standard KASAN will catch memory safety problems, while KMSAN specifically detects reads from uninitialized memory. Here, `complement` is always initialized by either zero allocation or explicit constructors/creators.
Hence, I'm comfortable setting `NeedsKMSAN = false`. I'm ready to call `set-results`.
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| 48/3 | 2026/09/20 20:11 | tool | set-results |
0mArgs:{
"KMSANReasoning": "The patch adds a boolean 'complement' field to DAMON's quota goal structures (struct damos_quota_goal and struct damos_sysfs_quota_goal) and exposes it via sysfs. \n\n1. Allocation \u0026 Initialization: Sysfs quota goal instances are allocated using kzalloc_obj(), which zeroes all fields by default, while kernel quota goal instances created via damos_new_quota_goal() explicitly initialize goal-\u003ecomplement = complement.\n2. User-space Exposure: The sysfs interface exposes this property via sysfs_emit() with formatted string output ('Y' or 'N'), avoiding any raw structure copying or padding leak to userspace (no copy_to_user of structs with padding).\n3. Arithmetic / Control Flow: The arithmetic operations performed on goal-\u003ecurrent_value based on complement do not alter buffer bounds, length calculations, or memory accesses.\n\nBecause no uninitialized memory can be read or leaked, there is no uninitialized memory risk that requires KMSAN. Standard KASAN/sanitizer configurations are sufficient to test these changes.",
"NeedsKMSAN": false
}Results: {
"KMSANReasoning": "The patch adds a boolean 'complement' field to DAMON's quota goal structures (struct damos_quota_goal and struct damos_sysfs_quota_goal) and exposes it via sysfs. \n\n1. Allocation \u0026 Initialization: Sysfs quota goal instances are allocated using kzalloc_obj(), which zeroes all fields by default, while kernel quota goal instances created via damos_new_quota_goal() explicitly initialize goal-\u003ecomplement = complement.\n2. User-space Exposure: The sysfs interface exposes this property via sysfs_emit() with formatted string output ('Y' or 'N'), avoiding any raw structure copying or padding leak to userspace (no copy_to_user of structs with padding).\n3. Arithmetic / Control Flow: The arithmetic operations performed on goal-\u003ecurrent_value based on complement do not alter buffer bounds, length calculations, or memory accesses.\n\nBecause no uninitialized memory can be read or leaked, there is no uninitialized memory risk that requires KMSAN. Standard KASAN/sanitizer configurations are sufficient to test these changes.",
"NeedsKMSAN": false
} |
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