AI Trajectory


Trajectory: (Expand/Collapse All)
Seq Timestamp Type Name Duration
0/0 2026/09/03 00:29 flow patch-triage
1m Args: 
null

Results: 
{
  "EnableConfigs": [
    "MODULES",
    "MEM_ALLOC_PROFILING"
  ],
  "FocusSymbols": [
    "init_module",
    "finit_module",
    "codetag_alloc_module_section",
    "codetag_free_module_sections"
  ],
  "KMSANReasoning": "The patch refactors the ELF section layout and allocation logic for standalone module sections (such as per-CPU sections and codetag/alloc_tag sections) during module loading in `kernel/module/main.c` and adjusts error handling in `mm/alloc_tag.c`.\n\nKMSAN vs KASAN analysis:\n- KMSAN detects reads of uninitialized memory and information leaks to user space. The patch does not introduce uninitialized stack or heap variables, does not leave structure paddings uninitialized, does not expose data to user space, and does not introduce branches on uninitialized state. The section data copied via `memcpy()` originates from already-loaded ELF image buffers.\n- Any potential memory management issues introduced by changes to section layouts, relocations, or separate memory allocations (such as out-of-bounds section reads/writes, buffer overflows, or use-after-free conditions) are addressable errors that are detected by standard KASAN.\n\nTherefore, dedicated KMSAN fuzzing is not required.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch changes core kernel module loading and layout logic for standalone sections (per-CPU sections and codetags/alloc tags) as well as memory allocation profiling tag reservation fallback handling when tags are not addressable. These changes are reachable via module loading syscalls (init_module and finit_module) and are worth fuzzing.",
  "WorthFuzzing": true
}
1/1 2026/09/03 00:29 action read-patch-diff
0m Args: 
null

Results: 
{
  "PatchDiff": "commit 9d7114f89f2af78fead39760e3cefbca211a249e\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Thu Sep 3 00:29:06 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/linux/module.h b/include/linux/module.h\nindex 96cc98568eea5..0c6f32ddcbf2d 100644\n--- a/include/linux/module.h\n+++ b/include/linux/module.h\n@@ -325,6 +325,8 @@ enum mod_mem_type {\n \tMOD_INIT_RODATA,\n \n \tMOD_MEM_NUM_TYPES,\n+\n+\tMOD_STANDALONE = -2,\n \tMOD_INVALID = -1,\n };\n \ndiff --git a/kernel/module/internal.h b/kernel/module/internal.h\nindex 061161cc79d90..4c738074a27b8 100644\n--- a/kernel/module/internal.h\n+++ b/kernel/module/internal.h\n@@ -29,6 +29,14 @@\n #define SH_ENTSIZE_TYPE_MASK\t((1UL \u003c\u003c SH_ENTSIZE_TYPE_BITS) - 1)\n #define SH_ENTSIZE_OFFSET_MASK\t((1UL \u003c\u003c (BITS_PER_LONG - SH_ENTSIZE_TYPE_BITS)) - 1)\n \n+/*\n+ * Marker for sections with a separate allocation, which are not placed\n+ * into mod-\u003emem[].\n+ */\n+#define SH_ENTSIZE_STANDALONE\t\t\t\t\t\\\n+\t(((unsigned long)MOD_STANDALONE \u0026 SH_ENTSIZE_TYPE_MASK)\t\\\n+\t \u003c\u003c SH_ENTSIZE_TYPE_SHIFT)\n+\n /* Maximum number of characters written by module_flags() */\n #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)\n \ndiff --git a/kernel/module/main.c b/kernel/module/main.c\nindex c1b34dc1e89ac..760449ddab224 100644\n--- a/kernel/module/main.c\n+++ b/kernel/module/main.c\n@@ -1617,14 +1617,8 @@ static int apply_relocations(struct module *mod, const struct load_info *info)\n \t\tif (infosec \u003e= info-\u003ehdr-\u003ee_shnum)\n \t\t\tcontinue;\n \n-\t\t/*\n-\t\t * Don't bother with non-allocated sections.\n-\t\t * An exception is the percpu section, which has separate allocations\n-\t\t * for individual CPUs. We relocate the percpu section in the initial\n-\t\t * ELF template and subsequently copy it to the per-CPU destinations.\n-\t\t */\n-\t\tif (!(info-\u003esechdrs[infosec].sh_flags \u0026 SHF_ALLOC) \u0026\u0026\n-\t\t    (!infosec || infosec != info-\u003eindex.pcpu))\n+\t\t/* Don't bother with non-allocated sections. */\n+\t\tif (!(info-\u003esechdrs[infosec].sh_flags \u0026 SHF_ALLOC))\n \t\t\tcontinue;\n \n \t\tif (info-\u003esechdrs[i].sh_flags \u0026 SHF_RELA_LIVEPATCH)\n@@ -1715,27 +1709,13 @@ static void __layout_sections(struct module *mod, struct load_info *info, bool i\n \n \t\t\tif ((s-\u003esh_flags \u0026 masks[m][0]) != masks[m][0]\n \t\t\t    || (s-\u003esh_flags \u0026 masks[m][1])\n-\t\t\t    || s-\u003esh_entsize != ~0UL\n+\t\t\t    || s-\u003esh_entsize != ~0UL /* offset or standalone */\n \t\t\t    || is_init != module_init_layout_section(sname))\n \t\t\t\tcontinue;\n \n \t\t\tif (WARN_ON_ONCE(type == MOD_INVALID))\n \t\t\t\tcontinue;\n \n-\t\t\t/*\n-\t\t\t * Do not allocate codetag memory as we load it into\n-\t\t\t * preallocated contiguous memory.\n-\t\t\t */\n-\t\t\tif (codetag_needs_module_section(mod, sname, s-\u003esh_size)) {\n-\t\t\t\t/*\n-\t\t\t\t * s-\u003esh_entsize won't be used but populate the\n-\t\t\t\t * type field to avoid confusion.\n-\t\t\t\t */\n-\t\t\t\ts-\u003esh_entsize = ((unsigned long)(type) \u0026 SH_ENTSIZE_TYPE_MASK)\n-\t\t\t\t\t\t\u003c\u003c SH_ENTSIZE_TYPE_SHIFT;\n-\t\t\t\tcontinue;\n-\t\t\t}\n-\n \t\t\ts-\u003esh_entsize = module_get_offset_and_type(mod, type, s, i);\n \t\t\tpr_debug(\"\\t%s\\n\", sname);\n \t\t}\n@@ -1745,16 +1725,10 @@ static void __layout_sections(struct module *mod, struct load_info *info, bool i\n /*\n  * Lay out the SHF_ALLOC sections in a way not dissimilar to how ld\n  * might -- code, read-only data, read-write data, small data.  Tally\n- * sizes, and place the offsets into sh_entsize fields: high bit means it\n- * belongs in init.\n+ * sizes, and place the offsets into sh_entsize fields.\n  */\n static void layout_sections(struct module *mod, struct load_info *info)\n {\n-\tunsigned int i;\n-\n-\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n-\t\tinfo-\u003esechdrs[i].sh_entsize = ~0UL;\n-\n \tpr_debug(\"Core section allocation order for %s:\\n\", mod-\u003ename);\n \t__layout_sections(mod, info, false);\n \n@@ -2800,7 +2774,6 @@ static int move_module(struct module *mod, struct load_info *info)\n {\n \tint i, ret;\n \tenum mod_mem_type t = MOD_MEM_NUM_TYPES;\n-\tbool codetag_section_found = false;\n \n \tfor_each_mod_mem_type(type) {\n \t\tif (!mod-\u003emem[type].size) {\n@@ -2820,34 +2793,13 @@ static int move_module(struct module *mod, struct load_info *info)\n \tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++) {\n \t\tvoid *dest;\n \t\tElf_Shdr *shdr = \u0026info-\u003esechdrs[i];\n-\t\tconst char *sname;\n \n-\t\tif (!(shdr-\u003esh_flags \u0026 SHF_ALLOC))\n+\t\tif (!(shdr-\u003esh_flags \u0026 SHF_ALLOC)\n+\t\t    || shdr-\u003esh_entsize == SH_ENTSIZE_STANDALONE)\n \t\t\tcontinue;\n \n-\t\tsname = info-\u003esecstrings + shdr-\u003esh_name;\n-\t\t/*\n-\t\t * Load codetag sections separately as they might still be used\n-\t\t * after module unload.\n-\t\t */\n-\t\tif (codetag_needs_module_section(mod, sname, shdr-\u003esh_size)) {\n-\t\t\tdest = codetag_alloc_module_section(mod, sname, shdr-\u003esh_size,\n-\t\t\t\t\tarch_mod_section_prepend(mod, i), shdr-\u003esh_addralign);\n-\t\t\tif (WARN_ON(!dest)) {\n-\t\t\t\tret = -EINVAL;\n-\t\t\t\tgoto out_err;\n-\t\t\t}\n-\t\t\tif (IS_ERR(dest)) {\n-\t\t\t\tret = PTR_ERR(dest);\n-\t\t\t\tgoto out_err;\n-\t\t\t}\n-\t\t\tcodetag_section_found = true;\n-\t\t} else {\n-\t\t\tenum mod_mem_type type = shdr-\u003esh_entsize \u003e\u003e SH_ENTSIZE_TYPE_SHIFT;\n-\t\t\tunsigned long offset = shdr-\u003esh_entsize \u0026 SH_ENTSIZE_OFFSET_MASK;\n-\n-\t\t\tdest = mod-\u003emem[type].base + offset;\n-\t\t}\n+\t\tdest = mod-\u003emem[shdr-\u003esh_entsize \u003e\u003e SH_ENTSIZE_TYPE_SHIFT].base +\n+\t\t       (shdr-\u003esh_entsize \u0026 SH_ENTSIZE_OFFSET_MASK);\n \n \t\tif (shdr-\u003esh_type != SHT_NOBITS) {\n \t\t\t/*\n@@ -2879,8 +2831,6 @@ static int move_module(struct module *mod, struct load_info *info)\n \tmodule_memory_restore_rox(mod);\n \twhile (t--)\n \t\tmodule_memory_free(mod, t);\n-\tif (codetag_section_found)\n-\t\tcodetag_free_module_sections(mod);\n \n \treturn ret;\n }\n@@ -2951,9 +2901,51 @@ static bool blacklisted(const char *module_name)\n }\n core_param(module_blacklist, module_blacklist, charp, 0400);\n \n+/*\n+ * Allocate codetag sections separately. They are loaded into preallocated\n+ * contiguous memory because they may still be used after the module is\n+ * unloaded.\n+ *\n+ * If the separate allocation overflows, allocate the section normally\n+ * so that the module can still be loaded.\n+ */\n+static int allocate_codetag_sections(struct load_info *info)\n+{\n+\tfor (unsigned int i = 1; i \u003c info-\u003ehdr-\u003ee_shnum; i++) {\n+\t\tElf_Shdr *shdr = \u0026info-\u003esechdrs[i];\n+\t\tconst char *sname = info-\u003esecstrings + shdr-\u003esh_name;\n+\t\tvoid *dest;\n+\n+\t\tif (!codetag_needs_module_section(info-\u003emod, sname, shdr-\u003esh_size))\n+\t\t\tcontinue;\n+\n+\t\tdest = codetag_alloc_module_section(info-\u003emod, sname, shdr-\u003esh_size,\n+\t\t\t\tarch_mod_section_prepend(info-\u003emod, i), shdr-\u003esh_addralign);\n+\t\tif (WARN_ON(!dest)) {\n+\t\t\tcodetag_free_module_sections(info-\u003emod);\n+\t\t\treturn -EINVAL;\n+\t\t}\n+\t\tif (dest == ERR_PTR(-EAGAIN))\n+\t\t\t/* Allocate the section as a regular section. */\n+\t\t\tcontinue;\n+\t\tif (IS_ERR(dest)) {\n+\t\t\tcodetag_free_module_sections(info-\u003emod);\n+\t\t\treturn PTR_ERR(dest);\n+\t\t}\n+\n+\t\tif (shdr-\u003esh_type != SHT_NOBITS)\n+\t\t\tmemcpy(dest, (void *)shdr-\u003esh_addr, shdr-\u003esh_size);\n+\t\tshdr-\u003esh_addr = (unsigned long)dest;\n+\t\tshdr-\u003esh_entsize = SH_ENTSIZE_STANDALONE;\n+\t}\n+\n+\treturn 0;\n+}\n+\n static struct module *layout_and_allocate(struct load_info *info, int flags)\n {\n \tstruct module *mod;\n+\tunsigned int i;\n \tint err;\n \n \t/* Allow arches to frob section contents and sizes.  */\n@@ -2967,8 +2959,13 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)\n \tif (err \u003c 0)\n \t\treturn ERR_PTR(err);\n \n+\t/* Repurpose sh_entsize to track where each section is allocated. */\n+\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n+\t\tinfo-\u003esechdrs[i].sh_entsize = ~0UL;\n+\n \t/* We will do a special allocation for per-cpu sections later. */\n-\tinfo-\u003esechdrs[info-\u003eindex.pcpu].sh_flags \u0026= ~(unsigned long)SHF_ALLOC;\n+\tif (info-\u003eindex.pcpu)\n+\t\tinfo-\u003esechdrs[info-\u003eindex.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;\n \n \t/*\n \t * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can\n@@ -2977,18 +2974,21 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)\n \t */\n \tmodule_mark_ro_after_init(info-\u003ehdr, info-\u003esechdrs, info-\u003esecstrings);\n \n-\t/*\n-\t * Determine total sizes, and put offsets in sh_entsize.  For now\n-\t * this is done generically; there doesn't appear to be any\n-\t * special cases for the architectures.\n-\t */\n+\t/* Allow codetag sections to be allocated separately first. */\n+\terr = allocate_codetag_sections(info);\n+\tif (err)\n+\t\treturn ERR_PTR(err);\n+\n+\t/* Determine total sizes and put offsets in sh_entsize. */\n \tlayout_sections(info-\u003emod, info);\n \tlayout_symtab(info-\u003emod, info);\n \n \t/* Allocate and move to the final place */\n \terr = move_module(info-\u003emod, info);\n-\tif (err)\n+\tif (err) {\n+\t\tcodetag_free_module_sections(info-\u003emod);\n \t\treturn ERR_PTR(err);\n+\t}\n \n \t/* Module has been copied to its final place now: return it. */\n \tmod = (void *)info-\u003esechdrs[info-\u003eindex.mod].sh_addr;\ndiff --git a/mm/alloc_tag.c b/mm/alloc_tag.c\nindex f30ef8dd24c70..8f13369b32ecd 100644\n--- a/mm/alloc_tag.c\n+++ b/mm/alloc_tag.c\n@@ -843,6 +843,52 @@ static int vm_module_tags_populate(void)\n \treturn 0;\n }\n \n+static void release_module_tags(struct module *mod, bool used)\n+{\n+\tMA_STATE(mas, \u0026mod_area_mt, module_tags.size, module_tags.size);\n+\tstruct alloc_tag *start_tag;\n+\tstruct alloc_tag *end_tag;\n+\tstruct module *val;\n+\n+\tmas_lock(\u0026mas);\n+\tmas_for_each_rev(\u0026mas, val, 0)\n+\t\tif (val == mod)\n+\t\t\tbreak;\n+\n+\tif (!val) /* module not found */\n+\t\tgoto out;\n+\n+\tif (!used)\n+\t\tgoto release_area;\n+\n+\tstart_tag = (struct alloc_tag *)(module_tags.start_addr + mas.index);\n+\tend_tag = (struct alloc_tag *)(module_tags.start_addr + mas.last);\n+\tif (!clean_unused_counters(start_tag, end_tag)) {\n+\t\tstruct alloc_tag *tag;\n+\n+\t\tfor (tag = start_tag; tag \u003c= end_tag; tag++) {\n+\t\t\tstruct alloc_tag_counters counter;\n+\n+\t\t\tif (!tag-\u003ecounters)\n+\t\t\t\tcontinue;\n+\n+\t\t\tcounter = alloc_tag_read(tag);\n+\t\t\tpr_info(\"%s:%u module %s func:%s has %llu allocated at module unload\\n\",\n+\t\t\t\ttag-\u003ect.filename, tag-\u003ect.lineno, tag-\u003ect.modname,\n+\t\t\t\ttag-\u003ect.function, counter.bytes);\n+\t\t}\n+\t} else {\n+\t\tused = false;\n+\t}\n+release_area:\n+\tmas_store(\u0026mas, used ? \u0026unloaded_mod : NULL);\n+\tval = mas_prev_range(\u0026mas, 0);\n+\tif (val == \u0026prepend_mod)\n+\t\tmas_store(\u0026mas, NULL);\n+out:\n+\tmas_unlock(\u0026mas);\n+}\n+\n static void *reserve_module_tags(struct module *mod, unsigned long size,\n \t\t\t\t unsigned int prepend, unsigned long align)\n {\n@@ -912,10 +958,12 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,\n \t\tint grow_res;\n \n \t\tmodule_tags.size = offset + size;\n-\t\tif (mem_alloc_profiling_enabled() \u0026\u0026 !tags_addressable()) {\n+\t\tif (!tags_addressable()) {\n \t\t\tshutdown_mem_profiling(true);\n-\t\t\tpr_warn(\"With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\\n\",\n-\t\t\t\tmod-\u003ename, NR_UNUSED_PAGEFLAG_BITS);\n+\t\t\tpr_warn_once(\"With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\\n\",\n+\t\t\t\t     mod-\u003ename, NR_UNUSED_PAGEFLAG_BITS);\n+\t\t\trelease_module_tags(mod, false);\n+\t\t\treturn ERR_PTR(-EAGAIN);\n \t\t}\n \n \t\tgrow_res = vm_module_tags_populate();\n@@ -923,6 +971,7 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,\n \t\t\tshutdown_mem_profiling(true);\n \t\t\tpr_err(\"Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\\n\",\n \t\t\t       mod-\u003ename);\n+\t\t\trelease_module_tags(mod, false);\n \t\t\treturn ERR_PTR(grow_res);\n \t\t}\n \t}\n@@ -930,52 +979,6 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,\n \treturn (struct alloc_tag *)(module_tags.start_addr + offset);\n }\n \n-static void release_module_tags(struct module *mod, bool used)\n-{\n-\tMA_STATE(mas, \u0026mod_area_mt, module_tags.size, module_tags.size);\n-\tstruct alloc_tag *start_tag;\n-\tstruct alloc_tag *end_tag;\n-\tstruct module *val;\n-\n-\tmas_lock(\u0026mas);\n-\tmas_for_each_rev(\u0026mas, val, 0)\n-\t\tif (val == mod)\n-\t\t\tbreak;\n-\n-\tif (!val) /* module not found */\n-\t\tgoto out;\n-\n-\tif (!used)\n-\t\tgoto release_area;\n-\n-\tstart_tag = (struct alloc_tag *)(module_tags.start_addr + mas.index);\n-\tend_tag = (struct alloc_tag *)(module_tags.start_addr + mas.last);\n-\tif (!clean_unused_counters(start_tag, end_tag)) {\n-\t\tstruct alloc_tag *tag;\n-\n-\t\tfor (tag = start_tag; tag \u003c= end_tag; tag++) {\n-\t\t\tstruct alloc_tag_counters counter;\n-\n-\t\t\tif (!tag-\u003ecounters)\n-\t\t\t\tcontinue;\n-\n-\t\t\tcounter = alloc_tag_read(tag);\n-\t\t\tpr_info(\"%s:%u module %s func:%s has %llu allocated at module unload\\n\",\n-\t\t\t\ttag-\u003ect.filename, tag-\u003ect.lineno, tag-\u003ect.modname,\n-\t\t\t\ttag-\u003ect.function, counter.bytes);\n-\t\t}\n-\t} else {\n-\t\tused = false;\n-\t}\n-release_area:\n-\tmas_store(\u0026mas, used ? \u0026unloaded_mod : NULL);\n-\tval = mas_prev_range(\u0026mas, 0);\n-\tif (val == \u0026prepend_mod)\n-\t\tmas_store(\u0026mas, NULL);\n-out:\n-\tmas_unlock(\u0026mas);\n-}\n-\n static int load_module(struct module *mod, struct codetag *start, struct codetag *stop)\n {\n \t/* Allocate module alloc_tag percpu counters */\n"
}
2/1 2026/09/03 00:29 agent patch-evaluator
0m Model: 
core

Args: 
null

Results: 
{
  "EnableConfigs": [
    "MODULES",
    "MEM_ALLOC_PROFILING"
  ],
  "FocusSymbols": [
    "init_module",
    "finit_module",
    "codetag_alloc_module_section",
    "codetag_free_module_sections"
  ],
  "Reasoning": "The patch changes core kernel module loading and layout logic for standalone sections (per-CPU sections and codetags/alloc tags) as well as memory allocation profiling tag reservation fallback handling when tags are not addressable. These changes are reachable via module loading syscalls (init_module and finit_module) and are worth fuzzing.",
  "WorthFuzzing": true
}

Instruction: 
You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
  even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
   Prefer non-static, non-inlined API entrypoint functions over internal static helper functions
   (which are inlined by the compiler and do not have distinct symbol addresses).
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs
   needed for Kbuild to compile the code statically into vmlinux. List them in the EnableConfigs
   output array, and DO NOT add a '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: 
For your convenience, here is the diff of the changes:
commit 9d7114f89f2af78fead39760e3cefbca211a249e
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Sep 3 00:29:06 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/linux/module.h b/include/linux/module.h
index 96cc98568eea5..0c6f32ddcbf2d 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -325,6 +325,8 @@ enum mod_mem_type {
 	MOD_INIT_RODATA,
 
 	MOD_MEM_NUM_TYPES,
+
+	MOD_STANDALONE = -2,
 	MOD_INVALID = -1,
 };
 
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 061161cc79d90..4c738074a27b8 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -29,6 +29,14 @@
 #define SH_ENTSIZE_TYPE_MASK	((1UL << SH_ENTSIZE_TYPE_BITS) - 1)
 #define SH_ENTSIZE_OFFSET_MASK	((1UL << (BITS_PER_LONG - SH_ENTSIZE_TYPE_BITS)) - 1)
 
+/*
+ * Marker for sections with a separate allocation, which are not placed
+ * into mod->mem[].
+ */
+#define SH_ENTSIZE_STANDALONE					\
+	(((unsigned long)MOD_STANDALONE & SH_ENTSIZE_TYPE_MASK)	\
+	 << SH_ENTSIZE_TYPE_SHIFT)
+
 /* Maximum number of characters written by module_flags() */
 #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
 
diff --git a/kernel/module/main.c b/kernel/module/main.c
index c1b34dc1e89ac..760449ddab224 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1617,14 +1617,8 @@ static int apply_relocations(struct module *mod, const struct load_info *info)
 		if (infosec >= info->hdr->e_shnum)
 			continue;
 
-		/*
-		 * Don't bother with non-allocated sections.
-		 * An exception is the percpu section, which has separate allocations
-		 * for individual CPUs. We relocate the percpu section in the initial
-		 * ELF template and subsequently copy it to the per-CPU destinations.
-		 */
-		if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC) &&
-		    (!infosec || infosec != info->index.pcpu))
+		/* Don't bother with non-allocated sections. */
+		if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC))
 			continue;
 
 		if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH)
@@ -1715,27 +1709,13 @@ static void __layout_sections(struct module *mod, struct load_info *info, bool i
 
 			if ((s->sh_flags & masks[m][0]) != masks[m][0]
 			    || (s->sh_flags & masks[m][1])
-			    || s->sh_entsize != ~0UL
+			    || s->sh_entsize != ~0UL /* offset or standalone */
 			    || is_init != module_init_layout_section(sname))
 				continue;
 
 			if (WARN_ON_ONCE(type == MOD_INVALID))
 				continue;
 
-			/*
-			 * Do not allocate codetag memory as we load it into
-			 * preallocated contiguous memory.
-			 */
-			if (codetag_needs_module_section(mod, sname, s->sh_size)) {
-				/*
-				 * s->sh_entsize won't be used but populate the
-				 * type field to avoid confusion.
-				 */
-				s->sh_entsize = ((unsigned long)(type) & SH_ENTSIZE_TYPE_MASK)
-						<< SH_ENTSIZE_TYPE_SHIFT;
-				continue;
-			}
-
 			s->sh_entsize = module_get_offset_and_type(mod, type, s, i);
 			pr_debug("\t%s\n", sname);
 		}
@@ -1745,16 +1725,10 @@ static void __layout_sections(struct module *mod, struct load_info *info, bool i
 /*
  * Lay out the SHF_ALLOC sections in a way not dissimilar to how ld
  * might -- code, read-only data, read-write data, small data.  Tally
- * sizes, and place the offsets into sh_entsize fields: high bit means it
- * belongs in init.
+ * sizes, and place the offsets into sh_entsize fields.
  */
 static void layout_sections(struct module *mod, struct load_info *info)
 {
-	unsigned int i;
-
-	for (i = 0; i < info->hdr->e_shnum; i++)
-		info->sechdrs[i].sh_entsize = ~0UL;
-
 	pr_debug("Core section allocation order for %s:\n", mod->name);
 	__layout_sections(mod, info, false);
 
@@ -2800,7 +2774,6 @@ static int move_module(struct module *mod, struct load_info *info)
 {
 	int i, ret;
 	enum mod_mem_type t = MOD_MEM_NUM_TYPES;
-	bool codetag_section_found = false;
 
 	for_each_mod_mem_type(type) {
 		if (!mod->mem[type].size) {
@@ -2820,34 +2793,13 @@ static int move_module(struct module *mod, struct load_info *info)
 	for (i = 0; i < info->hdr->e_shnum; i++) {
 		void *dest;
 		Elf_Shdr *shdr = &info->sechdrs[i];
-		const char *sname;
 
-		if (!(shdr->sh_flags & SHF_ALLOC))
+		if (!(shdr->sh_flags & SHF_ALLOC)
+		    || shdr->sh_entsize == SH_ENTSIZE_STANDALONE)
 			continue;
 
-		sname = info->secstrings + shdr->sh_name;
-		/*
-		 * Load codetag sections separately as they might still be used
-		 * after module unload.
-		 */
-		if (codetag_needs_module_section(mod, sname, shdr->sh_size)) {
-			dest = codetag_alloc_module_section(mod, sname, shdr->sh_size,
-					arch_mod_section_prepend(mod, i), shdr->sh_addralign);
-			if (WARN_ON(!dest)) {
-				ret = -EINVAL;
-				goto out_err;
-			}
-			if (IS_ERR(dest)) {
-				ret = PTR_ERR(dest);
-				goto out_err;
-			}
-			codetag_section_found = true;
-		} else {
-			enum mod_mem_type type = shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT;
-			unsigned long offset = shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK;
-
-			dest = mod->mem[type].base + offset;
-		}
+		dest = mod->mem[shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT].base +
+		       (shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK);
 
 		if (shdr->sh_type != SHT_NOBITS) {
 			/*
@@ -2879,8 +2831,6 @@ static int move_module(struct module *mod, struct load_info *info)
 	module_memory_restore_rox(mod);
 	while (t--)
 		module_memory_free(mod, t);
-	if (codetag_section_found)
-		codetag_free_module_sections(mod);
 
 	return ret;
 }
@@ -2951,9 +2901,51 @@ static bool blacklisted(const char *module_name)
 }
 core_param(module_blacklist, module_blacklist, charp, 0400);
 
+/*
+ * Allocate codetag sections separately. They are loaded into preallocated
+ * contiguous memory because they may still be used after the module is
+ * unloaded.
+ *
+ * If the separate allocation overflows, allocate the section normally
+ * so that the module can still be loaded.
+ */
+static int allocate_codetag_sections(struct load_info *info)
+{
+	for (unsigned int i = 1; i < info->hdr->e_shnum; i++) {
+		Elf_Shdr *shdr = &info->sechdrs[i];
+		const char *sname = info->secstrings + shdr->sh_name;
+		void *dest;
+
+		if (!codetag_needs_module_section(info->mod, sname, shdr->sh_size))
+			continue;
+
+		dest = codetag_alloc_module_section(info->mod, sname, shdr->sh_size,
+				arch_mod_section_prepend(info->mod, i), shdr->sh_addralign);
+		if (WARN_ON(!dest)) {
+			codetag_free_module_sections(info->mod);
+			return -EINVAL;
+		}
+		if (dest == ERR_PTR(-EAGAIN))
+			/* Allocate the section as a regular section. */
+			continue;
+		if (IS_ERR(dest)) {
+			codetag_free_module_sections(info->mod);
+			return PTR_ERR(dest);
+		}
+
+		if (shdr->sh_type != SHT_NOBITS)
+			memcpy(dest, (void *)shdr->sh_addr, shdr->sh_size);
+		shdr->sh_addr = (unsigned long)dest;
+		shdr->sh_entsize = SH_ENTSIZE_STANDALONE;
+	}
+
+	return 0;
+}
+
 static struct module *layout_and_allocate(struct load_info *info, int flags)
 {
 	struct module *mod;
+	unsigned int i;
 	int err;
 
 	/* Allow arches to frob section contents and sizes.  */
@@ -2967,8 +2959,13 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
 	if (err < 0)
 		return ERR_PTR(err);
 
+	/* Repurpose sh_entsize to track where each section is allocated. */
+	for (i = 0; i < info->hdr->e_shnum; i++)
+		info->sechdrs[i].sh_entsize = ~0UL;
+
 	/* We will do a special allocation for per-cpu sections later. */
-	info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;
+	if (info->index.pcpu)
+		info->sechdrs[info->index.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;
 
 	/*
 	 * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can
@@ -2977,18 +2974,21 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
 	 */
 	module_mark_ro_after_init(info->hdr, info->sechdrs, info->secstrings);
 
-	/*
-	 * Determine total sizes, and put offsets in sh_entsize.  For now
-	 * this is done generically; there doesn't appear to be any
-	 * special cases for the architectures.
-	 */
+	/* Allow codetag sections to be allocated separately first. */
+	err = allocate_codetag_sections(info);
+	if (err)
+		return ERR_PTR(err);
+
+	/* Determine total sizes and put offsets in sh_entsize. */
 	layout_sections(info->mod, info);
 	layout_symtab(info->mod, info);
 
 	/* Allocate and move to the final place */
 	err = move_module(info->mod, info);
-	if (err)
+	if (err) {
+		codetag_free_module_sections(info->mod);
 		return ERR_PTR(err);
+	}
 
 	/* Module has been copied to its final place now: return it. */
 	mod = (void *)info->sechdrs[info->index.mod].sh_addr;
diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c
index f30ef8dd24c70..8f13369b32ecd 100644
--- a/mm/alloc_tag.c
+++ b/mm/alloc_tag.c
@@ -843,6 +843,52 @@ static int vm_module_tags_populate(void)
 	return 0;
 }
 
+static void release_module_tags(struct module *mod, bool used)
+{
+	MA_STATE(mas, &mod_area_mt, module_tags.size, module_tags.size);
+	struct alloc_tag *start_tag;
+	struct alloc_tag *end_tag;
+	struct module *val;
+
+	mas_lock(&mas);
+	mas_for_each_rev(&mas, val, 0)
+		if (val == mod)
+			break;
+
+	if (!val) /* module not found */
+		goto out;
+
+	if (!used)
+		goto release_area;
+
+	start_tag = (struct alloc_tag *)(module_tags.start_addr + mas.index);
+	end_tag = (struct alloc_tag *)(module_tags.start_addr + mas.last);
+	if (!clean_unused_counters(start_tag, end_tag)) {
+		struct alloc_tag *tag;
+
+		for (tag = start_tag; tag <= end_tag; tag++) {
+			struct alloc_tag_counters counter;
+
+			if (!tag->counters)
+				continue;
+
+			counter = alloc_tag_read(tag);
+			pr_info("%s:%u module %s func:%s has %llu allocated at module unload\n",
+				tag->ct.filename, tag->ct.lineno, tag->ct.modname,
+				tag->ct.function, counter.bytes);
+		}
+	} else {
+		used = false;
+	}
+release_area:
+	mas_store(&mas, used ? &unloaded_mod : NULL);
+	val = mas_prev_range(&mas, 0);
+	if (val == &prepend_mod)
+		mas_store(&mas, NULL);
+out:
+	mas_unlock(&mas);
+}
+
 static void *reserve_module_tags(struct module *mod, unsigned long size,
 				 unsigned int prepend, unsigned long align)
 {
@@ -912,10 +958,12 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,
 		int grow_res;
 
 		module_tags.size = offset + size;
-		if (mem_alloc_profiling_enabled() && !tags_addressable()) {
+		if (!tags_addressable()) {
 			shutdown_mem_profiling(true);
-			pr_warn("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n",
-				mod->name, NR_UNUSED_PAGEFLAG_BITS);
+			pr_warn_once("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n",
+				     mod->name, NR_UNUSED_PAGEFLAG_BITS);
+			release_module_tags(mod, false);
+			return ERR_PTR(-EAGAIN);
 		}
 
 		grow_res = vm_module_tags_populate();
@@ -923,6 +971,7 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,
 			shutdown_mem_profiling(true);
 			pr_err("Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\n",
 			       mod->name);
+			release_module_tags(mod, false);
 			return ERR_PTR(grow_res);
 		}
 	}
@@ -930,52 +979,6 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,
 	return (struct alloc_tag *)(module_tags.start_addr + offset);
 }
 
-static void release_module_tags(struct module *mod, bool used)
-{
-	MA_STATE(mas, &mod_area_mt, module_tags.size, module_tags.size);
-	struct alloc_tag *start_tag;
-	struct alloc_tag *end_tag;
-	struct module *val;
-
-	mas_lock(&mas);
-	mas_for_each_rev(&mas, val, 0)
-		if (val == mod)
-			break;
-
-	if (!val) /* module not found */
-		goto out;
-
-	if (!used)
-		goto release_area;
-
-	start_tag = (struct alloc_tag *)(module_tags.start_addr + mas.index);
-	end_tag = (struct alloc_tag *)(module_tags.start_addr + mas.last);
-	if (!clean_unused_counters(start_tag, end_tag)) {
-		struct alloc_tag *tag;
-
-		for (tag = start_tag; tag <= end_tag; tag++) {
-			struct alloc_tag_counters counter;
-
-			if (!tag->counters)
-				continue;
-
-			counter = alloc_tag_read(tag);
-			pr_info("%s:%u module %s func:%s has %llu allocated at module unload\n",
-				tag->ct.filename, tag->ct.lineno, tag->ct.modname,
-				tag->ct.function, counter.bytes);
-		}
-	} else {
-		used = false;
-	}
-release_area:
-	mas_store(&mas, used ? &unloaded_mod : NULL);
-	val = mas_prev_range(&mas, 0);
-	if (val == &prepend_mod)
-		mas_store(&mas, NULL);
-out:
-	mas_unlock(&mas);
-}
-
 static int load_module(struct module *mod, struct codetag *start, struct codetag *stop)
 {
 	/* Allocate module alloc_tag percpu counters */

3/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 6681
							output: 29
							thoughts: 308

Thoughts: 
**Analyzing This Patch: A Deep Dive**

Okay, let's break down this patch. My initial thought is to understand the scope and potential implications, especially considering what config options might be involved. The patch touches several key files, and immediately I'm looking for the "why" behind these changes.

First, `include/linux/module.h` has a new enum value, `MOD_STANDALONE = -2`, added to `enum mod_mem_type`. That's the starting point. Then `kernel/module/internal.h` adds the `SH_ENTSIZE_STANDALONE` macro – so this `-2` is definitely connected to the standalone memory type. This means we're dealing with a distinct memory region for module loading.

The real meat of the changes seems to be in `kernel/module/main.c`. It's modifying core module layout and allocation routines: `apply_relocations`, `__layout_sections`, `layout_sections`, `move_module`, and `layout_and_allocate`. Plus, there's the introduction of `allocate_codetag_sections`. This looks like a significant refactoring of how sections, particularly codetag sections and percpu sections (standalone sections), are handled during module loading. The changes seem to be focused on ensuring that these new standalone sections are correctly managed during loading and relocation.

Finally, `mm/alloc_tag.c` sees some interesting reordering and error handling around module tag allocation. The `release_module_tags` function is called before `reserve_module_tags`. In `reserve_module_tags`, there's a specific check for `!tags_addressable()`, and if it's true, it releases tags and returns `-EAGAIN`. Also, there's a failure release for `vm_module_tags_populate()`. This is key. It implies a new approach or condition where memory tagging might fail and requires a retry or fallback. This could open interesting fuzzing possibilities.

Now, my next step is to figure out if this is fuzzable. I need to get a clear picture of what's controlled by configuration options. I'll need to use `grepper` or dive into the Kconfig files around `alloc_tag` and module loading, specifically looking for dependencies or triggers for these changes. I need to understand what configuration options expose these new paths, so I can create a fuzzing configuration that reaches these new features. This patch has definitely caught my attention.

4/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "MEM_ALLOC_PROFILING",
  "PathPrefix": "mm/"
}

Results: 
{
  "Output": "mm/Kconfig.debug=311=config PER_VMA_LOCK_STATS\n--\nmm/Kconfig.debug-322-\nmm/Kconfig.debug:323:config MEM_ALLOC_PROFILING\nmm/Kconfig.debug-324-\tbool \"Enable memory allocation profiling\"\n--\nmm/Kconfig.debug-335-\nmm/Kconfig.debug:336:config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/Kconfig.debug-337-\tbool \"Enable memory allocation profiling by default\"\nmm/Kconfig.debug-338-\tdefault y\nmm/Kconfig.debug:339:\tdepends on MEM_ALLOC_PROFILING\nmm/Kconfig.debug-340-\nmm/Kconfig.debug:341:config MEM_ALLOC_PROFILING_DEBUG\nmm/Kconfig.debug-342-\tbool \"Memory allocation profiler debugging\"\nmm/Kconfig.debug-343-\tdefault n\nmm/Kconfig.debug:344:\tdepends on MEM_ALLOC_PROFILING\nmm/Kconfig.debug:345:\tselect MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/Kconfig.debug-346-\thelp\n--\nmm/Makefile=149=obj-$(CONFIG_LAZY_MMU_MODE_KUNIT_TEST) += tests/lazy_mmu_mode_kunit.o\nmm/Makefile:150:obj-$(CONFIG_MEM_ALLOC_PROFILING) += alloc_tag.o\n--\nmm/alloc_tag.c-29-\nmm/alloc_tag.c:30:#ifdef CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/alloc_tag.c-31-static bool mem_profiling_support = true;\n--\nmm/alloc_tag.c=49=EXPORT_SYMBOL(_shared_alloc_tag);\n--\nmm/alloc_tag.c-51-\nmm/alloc_tag.c:52:DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\nmm/alloc_tag.c-53-\t\t\tmem_alloc_profiling_key);\n--\nmm/alloc_tag.c=1129=static __init bool need_page_alloc_tagging(void)\n--\nmm/alloc_tag.c-1136-\nmm/alloc_tag.c:1137:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/alloc_tag.c-1138-/*\n--\nmm/alloc_tag.c=1215=static void __init clear_early_alloc_pfn_tag_refs(void)\n--\nmm/alloc_tag.c-1268-}\nmm/alloc_tag.c:1269:#else /* !CONFIG_MEM_ALLOC_PROFILING_DEBUG */\nmm/alloc_tag.c-1270-static inline void __init clear_early_alloc_pfn_tag_refs(void) {}\nmm/alloc_tag.c:1271:#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */\nmm/alloc_tag.c-1272-\n--\nmm/alloc_tag.c=1290=static int proc_mem_profiling_handler(const struct ctl_table *table, int write,\n--\nmm/alloc_tag.c-1301-\nmm/alloc_tag.c:1302:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/alloc_tag.c-1303-\t\t/* User can't toggle profiling while debugging */\n--\nmm/page_alloc.c=1202=static void clear_highpages_kasan_tagged(struct page *page, int numpages)\n--\nmm/page_alloc.c-1216-\nmm/page_alloc.c:1217:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/page_alloc.c-1218-\n--\nmm/page_alloc.c=1283=static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr)\n--\nmm/page_alloc.c-1288-\nmm/page_alloc.c:1289:#else /* CONFIG_MEM_ALLOC_PROFILING */\nmm/page_alloc.c-1290-\n--\nmm/page_alloc.c=1294=static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr) {}\nmm/page_alloc.c-1295-\nmm/page_alloc.c:1296:#endif /* CONFIG_MEM_ALLOC_PROFILING */\nmm/page_alloc.c-1297-\n--\nmm/page_ext.c=80=static struct page_ext_operations *page_ext_ops[] __initdata = {\n--\nmm/page_ext.c-86-#endif\nmm/page_ext.c:87:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/page_ext.c-88-\t\u0026page_alloc_tagging_ops,\n--\nmm/page_ext.c=100=static unsigned long total_usage;\nmm/page_ext.c-101-\nmm/page_ext.c:102:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/page_ext.c-103-/*\n--\nmm/percpu-internal.h=35=struct pcpuobj_ext {\n--\nmm/percpu-internal.h-38-#endif\nmm/percpu-internal.h:39:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/percpu-internal.h-40-\tunion codetag_ref\ttag;\n--\nmm/percpu-internal.h-43-\nmm/percpu-internal.h:44:#if defined(CONFIG_MEMCG) || defined(CONFIG_MEM_ALLOC_PROFILING)\nmm/percpu-internal.h-45-#define NEED_PCPUOBJ_EXT\n--\nmm/percpu-internal.h=90=static inline bool need_pcpuobj_ext(void)\nmm/percpu-internal.h-91-{\nmm/percpu-internal.h:92:\tif (IS_ENABLED(CONFIG_MEM_ALLOC_PROFILING))\nmm/percpu-internal.h-93-\t\treturn true;\n--\nmm/percpu.c=1688=static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)\n--\nmm/percpu.c-1692-\nmm/percpu.c:1693:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/percpu.c-1694-static void pcpu_alloc_tag_alloc_hook(struct pcpu_chunk *chunk, int off,\n--\nmm/show_mem.c=408=void __show_mem(unsigned int filter, const nodemask_t *nodemask,\n--\nmm/show_mem.c-434-#endif\nmm/show_mem.c:435:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/show_mem.c-436-\tstatic DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);\n--\nmm/slab.h=604=struct slabobj_ext {\n--\nmm/slab.h-612-#endif\nmm/slab.h:613:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slab.h-614-\t\tunion codetag_ref _ctref;\n--\nmm/slab.h-618-\nmm/slab.h:619:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slab.h:620:DECLARE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\nmm/slab.h-621-\t\t\t slab_obj_ext_has_codetag_key);\n--\nmm/slab.h=623=static inline bool slab_obj_ext_has_codetag(void)\nmm/slab.h-624-{\nmm/slab.h:625:\treturn static_branch_maybe(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\nmm/slab.h-626-\t\t\t\t   \u0026slab_obj_ext_has_codetag_key);\n--\nmm/slab.h=807=slab_obj_ext_set_objcg(struct slab *slab, struct slabobj_ext *obj_ext,\n--\nmm/slab.h-816-\nmm/slab.h:817:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slab.h-818-static inline union codetag_ref *\n--\nmm/slub.c=214=static DEFINE_STATIC_KEY_FALSE(strict_numa);\n--\nmm/slub.c-216-\nmm/slub.c:217:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slub.c:218:DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\nmm/slub.c-219-\t\t\tslab_obj_ext_has_codetag_key);\n--\nmm/slub.c=2069=static inline void dec_slabs_node(struct kmem_cache *s, int node,\n--\nmm/slub.c-2086-\nmm/slub.c:2087:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/slub.c-2088-\n--\nmm/slub.c=2124=static inline void handle_failed_objexts_alloc(struct slab *slab,\n--\nmm/slub.c-2149-\nmm/slub.c:2150:#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */\nmm/slub.c-2151-\n--\nmm/slub.c=2154=static inline void handle_failed_objexts_alloc(struct slab *slab,\n--\nmm/slub.c-2156-\nmm/slub.c:2157:#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */\nmm/slub.c-2158-\n--\nmm/slub.c=2346=static inline void alloc_slab_obj_exts_early(struct kmem_cache *s,\n--\nmm/slub.c-2352-\nmm/slub.c:2353:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slub.c-2354-\n--\nmm/slub.c=2469=static void __init slab_obj_ext_has_codetag_init(void)\n--\nmm/slub.c-2480-\nmm/slub.c:2481:#else /* CONFIG_MEM_ALLOC_PROFILING */\nmm/slub.c-2482-\n--\nmm/slub.c=2495=static inline void slab_obj_ext_has_codetag_init(void)\n--\nmm/slub.c-2498-\nmm/slub.c:2499:#endif /* CONFIG_MEM_ALLOC_PROFILING */\nmm/slub.c-2500-\n"
}
5/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 10378
							output: 27
							thoughts: 23

Thoughts: 
Here's my take on the thought process, as if it were my own:

**Kconfig Deep Dive: CODE_TAGGING and MEM_ALLOC_PROFILING**

Alright, time to get my hands dirty and dive into some Kconfig options. Let's see... what's on the agenda today? Ah, yes, `CODE_TAGGING` and `MEM_ALLOC_PROFILING`. Those two are often intertwined, especially when we're thinking about low-level debugging and performance analysis. I need to refresh my understanding of how they play together in the grand scheme of things, and what implications each has on the kernel's behavior and performance, and the amount of instrumentation to be aware of. I'll take a look at the code to determine how this affects the system, and what the trade-offs are. I need to make a note of where these are used as this could affect the entire system.

6/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "config CODE_TAGGING",
  "PathPrefix": "lib/"
}

Results: 
{
  "Output": "lib/Kconfig.debug=1014=config DEBUG_STACKOVERFLOW\n--\nlib/Kconfig.debug-1031-\nlib/Kconfig.debug:1032:config CODE_TAGGING\nlib/Kconfig.debug-1033-\tbool\n"
}
7/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 10702
							output: 35
							thoughts: 20

Thoughts: 
Here's my take on the thought process, from an expert's perspective:

**Debugging Kconfig in the Wild**

Okay, so I'm deep in the weeds, chasing down a bug. The problem's probably related to some debug configuration option. Knowing this codebase, I can almost smell where the issue might be. My gut tells me to zero in on `lib/Kconfig.debug`. It's a key file for any debugging-related settings. Specifically, I'm thinking that line 1032 might hold a clue. It's a decent starting point for digging in and taking a look. Let's see what's what.

8/2 2026/09/03 00:29 tool read-file
0m Args: 
{
  "File": "lib/Kconfig.debug",
  "FirstLine": 1025,
  "LineCount": 40
}

Results: 
{
  "Contents": "1025:\t\t  involved.\n1026:\t\n1027:\t\t  Use this in cases where you see apparently random memory\n1028:\t\t  corruption, especially if it appears in 'struct thread_info'\n1029:\t\n1030:\t\t  If in doubt, say \"N\".\n1031:\t\n1032:\tconfig CODE_TAGGING\n1033:\t\tbool\n1034:\t\tselect KALLSYMS\n1035:\t\n1036:\tsource \"lib/Kconfig.kasan\"\n1037:\tsource \"lib/Kconfig.kfence\"\n1038:\tsource \"lib/Kconfig.kmsan\"\n1039:\t\n1040:\tendmenu # \"Memory Debugging\"\n1041:\t\n1042:\tconfig DEBUG_SHIRQ\n1043:\t\tbool \"Debug shared IRQ handlers\"\n1044:\t\tdepends on DEBUG_KERNEL\n1045:\t\thelp\n1046:\t\t  Enable this to generate a spurious interrupt just before a shared\n1047:\t\t  interrupt handler is deregistered (generating one when registering\n1048:\t\t  is currently disabled). Drivers need to handle this correctly. Some\n1049:\t\t  don't and need to be caught.\n1050:\t\n1051:\tmenu \"Debug Oops, Lockups and Hangs\"\n1052:\t\n1053:\tconfig PANIC_ON_OOPS\n1054:\t\tbool \"Panic on Oops\"\n1055:\t\thelp\n1056:\t\t  Say Y here to enable the kernel to panic when it oopses. This\n1057:\t\t  has the same effect as setting oops=panic on the kernel command\n1058:\t\t  line.\n1059:\t\n1060:\t\t  This feature is useful to ensure that the kernel does not do\n1061:\t\t  anything erroneous after an oops which could result in data\n1062:\t\t  corruption or other issues.\n1063:\t\n1064:\t\t  Say N if unsure.\n"
}
9/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 11437
							output: 34
							thoughts: 19

Thoughts: 
Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Diving into Debug Configuration**

Okay, so I'm troubleshooting something, and my gut feeling is telling me it's likely a configuration issue related to debugging. Given that, let's zero in on `mm/Kconfig.debug`. Specifically, I'm thinking the sweet spot to look for this issue might be around line 320. My experience suggests that's a fairly common spot for memory management debug options, or perhaps the dependencies of such options, to be defined. I'm going to start there and see what jumps out, paying close attention to any conditionals or relationships with other config options. From there, I can trace dependencies if needed.

10/2 2026/09/03 00:29 tool read-file
0m Args: 
{
  "File": "mm/Kconfig.debug",
  "FirstLine": 315,
  "LineCount": 40
}

Results: 
{
  "Contents": " 315:\t\t  faults handled under protection of per-vma locks. When enabled, the\n 316:\t\t  counters are exposed in /proc/vmstat. This information is useful for\n 317:\t\t  kernel developers to evaluate effectiveness of per-vma locks and to\n 318:\t\t  identify pathological cases. Counting these events introduces a small\n 319:\t\t  overhead in the page fault path.\n 320:\t\n 321:\t\t  If in doubt, say N.\n 322:\t\n 323:\tconfig MEM_ALLOC_PROFILING\n 324:\t\tbool \"Enable memory allocation profiling\"\n 325:\t\tdefault n\n 326:\t\tdepends on MMU\n 327:\t\tdepends on PROC_FS\n 328:\t\tselect CODE_TAGGING\n 329:\t\tselect PAGE_EXTENSION\n 330:\t\tselect SLAB_OBJ_EXT\n 331:\t\thelp\n 332:\t\t  Track allocation source code and record total allocation size\n 333:\t\t  initiated at that code location. The mechanism can be used to track\n 334:\t\t  memory leaks with a low performance and memory impact.\n 335:\t\n 336:\tconfig MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\n 337:\t\tbool \"Enable memory allocation profiling by default\"\n 338:\t\tdefault y\n 339:\t\tdepends on MEM_ALLOC_PROFILING\n 340:\t\n 341:\tconfig MEM_ALLOC_PROFILING_DEBUG\n 342:\t\tbool \"Memory allocation profiler debugging\"\n 343:\t\tdefault n\n 344:\t\tdepends on MEM_ALLOC_PROFILING\n 345:\t\tselect MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\n 346:\t\thelp\n 347:\t\t  Adds warnings with helpful error messages for memory allocation\n 348:\t\t  profiling.\n"
}
11/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 12143
							output: 19
							thoughts: 15

Thoughts: 
Okay, here's my attempt at summarizing that thought process, tailored for an expert audience:

**Investigating the `CODE_TAGGING` Selection Criteria**

Alright, so I'm trying to figure out the scope of something that involves `CODE_TAGGING`. My initial thought is to pause and try to get a holistic view of its purpose.

The implicit assumption is that there are other selection methods, features, rules, or inputs in play. Thinking systematically, I need to know: what criteria besides the explicitly mentioned one determine the selection of `CODE_TAGGING`? What are all the triggers, constraints, or contextual factors influencing its invocation? I need to understand the full set of conditions, not just the obvious one. So, what else is contributing to, or potentially influencing, a process that chooses `CODE_TAGGING`?

12/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "select CODE_TAGGING"
}

Results: 
{
  "Output": "mm/Kconfig.debug=323=config MEM_ALLOC_PROFILING\n--\nmm/Kconfig.debug-327-\tdepends on PROC_FS\nmm/Kconfig.debug:328:\tselect CODE_TAGGING\nmm/Kconfig.debug-329-\tselect PAGE_EXTENSION\n"
}
13/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 12439
							output: 29
							thoughts: 187

Thoughts: 
**Analyzing Module Loading Changes**

Okay, so I need to dig into this patch related to module loading, specifically because the `MODULES` configuration option is involved, as indicated by the core module loading code (`kernel/module/main.c`). My first step is to trace the changes to understand the impact.

Let's see, I've got `kernel/module/main.c` and `mm/alloc_tag.c` as the primary affected files. I need to pinpoint the specific functions modified to understand the scope. From a quick glance at `kernel/module/main.c`, it looks like these functions have been touched: `apply_relocations`, `__layout_sections`, `layout_sections`, `move_module`, `allocate_codetag_sections`, and `layout_and_allocate`. I should note that they are all static, which means their visibility is limited to the file scope, usually improving performance.

Crucially, I see that the `load_module` function calls `layout_and_allocate`. And `load_module` itself is a very important entry point, which is called indirectly through the `init_module` and `finit_module` system calls. This gives me a good entry point to start my investigation.

Next, I need to understand the call graphs. So, I will check the callers of both `layout_and_allocate` and `load_module`. This will help me understand how this change propagates through the system. I'll be looking for any surprising dependencies or potential side effects within the module loading process, or anything that might lead to a larger change in how the modules are being loaded and initialized.

14/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "layout_and_allocate",
  "PathPrefix": "kernel/module/"
}

Results: 
{
  "Output": "kernel/module/internal.h=164=static inline bool set_livepatch_module(struct module *mod)\n--\nkernel/module/internal.h-179- * \tor being processed on our \u0026modules list. This happens on early_mod_check()\nkernel/module/internal.h:180: * \tright before layout_and_allocate(). The kernel would have already\nkernel/module/internal.h-181- * \tvmalloc()'d space for the entire module through finit_module(). If\n--\nkernel/module/internal.h-187- *\tof this allocated yet another private kernel copy of the module space in\nkernel/module/internal.h:188: *\tlayout_and_allocate() but after this determined in add_unformed_module()\nkernel/module/internal.h-189- *\tthat another module with the same name is already loaded or being processed.\n--\nkernel/module/main.c=2912=static int allocate_codetag_sections(struct load_info *info)\n--\nkernel/module/main.c-2944-\nkernel/module/main.c:2945:static struct module *layout_and_allocate(struct load_info *info, int flags)\nkernel/module/main.c-2946-{\n--\nkernel/module/main.c=3433=static int load_module(struct load_info *info, const char __user *uargs,\n--\nkernel/module/main.c-3470-\t/* Figure out module layout, and allocate all the memory. */\nkernel/module/main.c:3471:\tmod = layout_and_allocate(info, flags);\nkernel/module/main.c-3472-\tif (IS_ERR(mod)) {\n--\nkernel/module/stats.c-42- *      from kernel_read_file_from_fd() is freed right away.\nkernel/module/stats.c:43: *   c) layout_and_allocate() allocates space for the final resting\nkernel/module/stats.c-44- *      place where we would keep the module if it were to be processed\n--\nkernel/module/stats.c-88- *   a) FAIL_DUP_MOD_BECOMING: at the end of early_mod_check() before\nkernel/module/stats.c:89: *\tlayout_and_allocate().\nkernel/module/stats.c-90- *\t- with module decompression: 2 virtual memory allocation calls\nkernel/module/stats.c-91- *\t- without module decompression: 1 virtual memory allocation calls\nkernel/module/stats.c:92: *   b) FAIL_DUP_MOD_LOAD: after layout_and_allocate() on add_unformed_module()\nkernel/module/stats.c-93- *   \t- with module decompression 3 virtual memory allocation calls\n--\nkernel/module/stats.c=100=static LIST_HEAD(dup_failed_modules);\n--\nkernel/module/stats.c-139- *     at the end of early_mod_check() prevents duplicate allocations\nkernel/module/stats.c:140: *     on layout_and_allocate() for modules already being processed. These\nkernel/module/stats.c-141- *     duplicate failed modules are non-fatal, however they typically are\n--\nkernel/module/stats.c-166- *     is unique.  A module can still fail to load if we detect the module is\nkernel/module/stats.c:167: *     loaded after we allocate space for it with layout_and_allocate(), we do\nkernel/module/stats.c-168- *     this check right before processing the module as live and run its\n--\nkernel/module/stats.c-180- *  * failed_becoming: how many modules failed after we kernel_read_file_from_fd()\nkernel/module/stats.c:181: *    it and before we allocate memory for it with layout_and_allocate(). This\nkernel/module/stats.c-182- *    counter is never incremented if you manage to validate the module and\nkernel/module/stats.c:183: *    call layout_and_allocate() for it.\nkernel/module/stats.c-184- *  * failed_load_modules: how many modules failed once we've allocated our\nkernel/module/stats.c:185: *    private space for our module using layout_and_allocate(). These failures\nkernel/module/stats.c-186- *    should hopefully mostly be dealt with already. Races in theory could\n"
}
15/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 14123
							output: 31
							thoughts: 53

Thoughts: 
Okay, let's break this down.

**Diving into Kernel Module Loading**

Alright, so I need to understand how kernel modules are loaded, specifically looking at the system call level. The first thing that jumps out is that `finit_module` and `init_module` are the user-space interface – they're the direct system calls exposed to applications or, in this case, a privileged process like Syzkaller. My goal is to understand how these syscalls work under the hood. So, next, I'll need to locate the syscall entrypoints in the kernel source, probably in `kernel/module/main.c`. That's where the magic likely happens – where the kernel figures out what to *do* with those user-space commands to load a module.

16/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "SYSCALL_DEFINE.*module",
  "PathPrefix": "kernel/module/"
}

Results: 
{
  "Output": "kernel/module/main.c=802=static void free_module(struct module *mod);\nkernel/module/main.c-803-\nkernel/module/main.c:804:SYSCALL_DEFINE2(delete_module, const char __user *, name_user,\nkernel/module/main.c-805-\t\tunsigned int, flags)\n--\nkernel/module/main.c=3433=static int load_module(struct load_info *info, const char __user *uargs,\n--\nkernel/module/main.c-3650-\nkernel/module/main.c:3651:SYSCALL_DEFINE3(init_module, void __user *, umod,\nkernel/module/main.c-3652-\t\tunsigned long, len, const char __user *, uargs)\n--\nkernel/module/main.c=3797=static int idempotent_init_module(struct file *f, const char __user * uargs, int flags)\n--\nkernel/module/main.c-3815-\nkernel/module/main.c:3816:SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)\nkernel/module/main.c-3817-{\n"
}
17/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 14699
							output: 22
							thoughts: 68

Thoughts: 
**Investigating `alloc_tag.c` Function Usage**

Okay, let's dive into this. My initial thought is to examine the `alloc_tag.c` file directly, specifically focusing on the functions defined within it. My primary targets are `reserve_module_tags` and `release_module_tags`. I see they're declared as static within `mm/alloc_tag.c`. My next question is, where are these functions actually *used*? What's the call path? To figure that out, I'm going to shift my focus to the codetag module callbacks. That seems like the most logical place to start tracing their execution flow.

18/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "codetag_alloc_module_section"
}

Results: 
{
  "Output": "include/linux/codetag.h=92=bool codetag_needs_module_section(struct module *mod, const char *name,\ninclude/linux/codetag.h-93-\t\t\t\t  unsigned long size);\ninclude/linux/codetag.h:94:void *codetag_alloc_module_section(struct module *mod, const char *name,\ninclude/linux/codetag.h-95-\t\t\t\t   unsigned long size, unsigned int prepend,\n--\ninclude/linux/codetag.h=107=static inline void *\ninclude/linux/codetag.h:108:codetag_alloc_module_section(struct module *mod, const char *name,\ninclude/linux/codetag.h-109-\t\t\t     unsigned long size, unsigned int prepend,\n--\nkernel/module/main.c=2912=static int allocate_codetag_sections(struct load_info *info)\n--\nkernel/module/main.c-2921-\nkernel/module/main.c:2922:\t\tdest = codetag_alloc_module_section(info-\u003emod, sname, shdr-\u003esh_size,\nkernel/module/main.c-2923-\t\t\t\tarch_mod_section_prepend(info-\u003emod, i), shdr-\u003esh_addralign);\n--\nlib/codetag.c=255=bool codetag_needs_module_section(struct module *mod, const char *name,\n--\nlib/codetag.c-282-\nlib/codetag.c:283:void *codetag_alloc_module_section(struct module *mod, const char *name,\nlib/codetag.c-284-\t\t\t\t   unsigned long size, unsigned int prepend,\n"
}
19/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 15358
							output: 22
							thoughts: 23

Thoughts: 
Here's my summary, as if I were thinking these thoughts:

**Diving into the Code: `codetag.c` and Section Allocation**

Okay, time to get my hands dirty. Let's start with `lib/codetag.c`. I need to understand how these code tags are being managed. I'm particularly interested in the allocation process. Specifically, I'll be focusing on `codetag_alloc_module_section`. This function is likely the key to how we're carving out memory for these tags within the module structure. I want to see how it's done, any potential gotchas with memory management, and if there are any obvious areas for optimization or potential issues that could lead to fragmentation. Knowing this will give me a better handle on the overall efficiency of our current tagging implementation.

20/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "codetag_free_module_sections"
}

Results: 
{
  "Output": "include/linux/codetag.h=94=void *codetag_alloc_module_section(struct module *mod, const char *name,\n--\ninclude/linux/codetag.h-96-\t\t\t\t   unsigned long align);\ninclude/linux/codetag.h:97:void codetag_free_module_sections(struct module *mod);\ninclude/linux/codetag.h-98-void codetag_module_replaced(struct module *mod, struct module *new_mod);\n--\ninclude/linux/codetag.h=108=codetag_alloc_module_section(struct module *mod, const char *name,\n--\ninclude/linux/codetag.h-110-\t\t\t     unsigned long align) { return NULL; }\ninclude/linux/codetag.h:111:static inline void codetag_free_module_sections(struct module *mod) {}\ninclude/linux/codetag.h-112-static inline void codetag_module_replaced(struct module *mod, struct module *new_mod) {}\n--\nkernel/module/main.c=2912=static int allocate_codetag_sections(struct load_info *info)\n--\nkernel/module/main.c-2924-\t\tif (WARN_ON(!dest)) {\nkernel/module/main.c:2925:\t\t\tcodetag_free_module_sections(info-\u003emod);\nkernel/module/main.c-2926-\t\t\treturn -EINVAL;\n--\nkernel/module/main.c-2931-\t\tif (IS_ERR(dest)) {\nkernel/module/main.c:2932:\t\t\tcodetag_free_module_sections(info-\u003emod);\nkernel/module/main.c-2933-\t\t\treturn PTR_ERR(dest);\n--\nkernel/module/main.c=2945=static struct module *layout_and_allocate(struct load_info *info, int flags)\n--\nkernel/module/main.c-2988-\tif (err) {\nkernel/module/main.c:2989:\t\tcodetag_free_module_sections(info-\u003emod);\nkernel/module/main.c-2990-\t\treturn ERR_PTR(err);\n--\nkernel/module/main.c=3002=static void module_deallocate(struct module *mod, struct load_info *info)\n--\nkernel/module/main.c-3005-\tmodule_arch_freeing_init(mod);\nkernel/module/main.c:3006:\tcodetag_free_module_sections(mod);\nkernel/module/main.c-3007-\n--\nlib/codetag.c=283=void *codetag_alloc_module_section(struct module *mod, const char *name,\n--\nlib/codetag.c-307-\nlib/codetag.c:308:void codetag_free_module_sections(struct module *mod)\nlib/codetag.c-309-{\n"
}
21/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 16315
							output: 34
							thoughts: 59

Thoughts: 
Here's my take:

**Investigating Codetag Memory Management**

Okay, so I'm looking into the codetag module, specifically how it allocates and frees sections. My immediate focus is on the functions `codetag_alloc_module_section` and `codetag_free_module_sections`. I know these are exported or defined within `lib/codetag.c`. Now, the best place to jump in is probably directly into the source code to understand the mechanisms. I'm going to quickly navigate to `lib/codetag.c`, and I'm guessing that line 283 or around that area is a good starting point to inspect the allocation and deallocation logic. Let's see what's going on there.

22/2 2026/09/03 00:29 tool read-file
0m Args: 
{
  "File": "lib/codetag.c",
  "FirstLine": 275,
  "LineCount": 50
}

Results: 
{
  "Contents": " 275:\t\t\t\tbreak;\n 276:\t\t\t}\n 277:\t\t}\n 278:\t\tmutex_unlock(\u0026codetag_lock);\n 279:\t\n 280:\t\treturn ret;\n 281:\t}\n 282:\t\n 283:\tvoid *codetag_alloc_module_section(struct module *mod, const char *name,\n 284:\t\t\t\t\t   unsigned long size, unsigned int prepend,\n 285:\t\t\t\t\t   unsigned long align)\n 286:\t{\n 287:\t\tconst char *type_name = name + strlen(CODETAG_SECTION_PREFIX);\n 288:\t\tstruct codetag_type *cttype;\n 289:\t\tvoid *ret = ERR_PTR(-EINVAL);\n 290:\t\n 291:\t\tmutex_lock(\u0026codetag_lock);\n 292:\t\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n 293:\t\t\tif (strcmp(type_name, cttype-\u003edesc.section) == 0) {\n 294:\t\t\t\tif (WARN_ON(!cttype-\u003edesc.alloc_section_mem))\n 295:\t\t\t\t\tbreak;\n 296:\t\n 297:\t\t\t\tdown_write(\u0026cttype-\u003emod_lock);\n 298:\t\t\t\tret = cttype-\u003edesc.alloc_section_mem(mod, size, prepend, align);\n 299:\t\t\t\tup_write(\u0026cttype-\u003emod_lock);\n 300:\t\t\t\tbreak;\n 301:\t\t\t}\n 302:\t\t}\n 303:\t\tmutex_unlock(\u0026codetag_lock);\n 304:\t\n 305:\t\treturn ret;\n 306:\t}\n 307:\t\n 308:\tvoid codetag_free_module_sections(struct module *mod)\n 309:\t{\n 310:\t\tstruct codetag_type *cttype;\n 311:\t\n 312:\t\tmutex_lock(\u0026codetag_lock);\n 313:\t\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n 314:\t\t\tif (!cttype-\u003edesc.free_section_mem)\n 315:\t\t\t\tcontinue;\n 316:\t\n 317:\t\t\tdown_write(\u0026cttype-\u003emod_lock);\n 318:\t\t\tcttype-\u003edesc.free_section_mem(mod, false);\n 319:\t\t\tup_write(\u0026cttype-\u003emod_lock);\n 320:\t\t}\n 321:\t\tmutex_unlock(\u0026codetag_lock);\n 322:\t}\n 323:\t\n 324:\tvoid codetag_module_replaced(struct module *mod, struct module *new_mod)\n"
}
23/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 17288
							output: 27
							thoughts: 58

Thoughts: 
**Investigating the `alloc_tag` Allocation Mechanism**

Okay, so I'm digging into this `alloc_tag` stuff. The clue I have is that the allocation function, `cttype->desc.alloc_section_mem`, related to `alloc_tag`, is registered within `mm/alloc_tag.c`. My next move, naturally, is to pinpoint *where* exactly `alloc_section_mem` is actually *set* within that `mm/alloc_tag.c` file. Gotta trace its definition to understand its function. I need to figure out how this thing is being initialized and configured. That's the key to understanding its overall behavior.

24/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "alloc_section_mem",
  "PathPrefix": "mm/"
}

Results: 
{
  "Output": "mm/alloc_tag.c=1337=static int __init alloc_tag_init(void)\n--\nmm/alloc_tag.c-1343-\t\t.needs_section_mem\t= needs_section_mem,\nmm/alloc_tag.c:1344:\t\t.alloc_section_mem\t= reserve_module_tags,\nmm/alloc_tag.c-1345-\t\t.free_section_mem\t= release_module_tags,\n"
}
25/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 17643
							output: 33
							thoughts: 636

Thoughts: 
**Analyzing a Kernel Module Patch for Fuzzing Opportunities**

Okay, let's break down this patch. It's fundamentally overhauling how the kernel handles module layout and memory allocation for specific section types, specifically things like codetag and percpu sections. I see they're introducing `allocate_codetag_sections()` which is now called *before* the regular section layout process. That's a significant change. It looks like they're marking these standalone sections with `SH_ENTSIZE_STANDALONE`, and if allocation fails in the tag path with `EAGAIN`, it falls back to a regular allocation. The `move_module()` function is then updated to skip the standalone sections. Percpu sections are also getting this treatment, using `SH_ENTSIZE_STANDALONE` rather than some custom logic during relocation. And there's also a fallback implemented, using `ERR_PTR(-EAGAIN)`, in `mm/alloc_tag.c` if `tags_addressable()` isn't true, which forces the module loader to use the normal allocation process.

This is definitely worth a closer look for fuzzing! It's touching core kernel module loading logic in `kernel/module/main.c` and how memory allocation tags are managed within `mm/alloc_tag.c`. Module loading is easily accessible through `init_module` and `finit_module` system calls, which Syzkaller already targets within QEMU and GCE environments.

My thinking is that the ELF parsing, section layout, relocation handling, the fallback mechanisms, and the error unwinding logic when loading modules are all *critical* code paths. These are prime targets for memory corruption bugs, layout bugs, size calculation errors, or even use-after-free vulnerabilities.

So, let's focus on identifying the key entry points and functions. I need to make sure I'm zeroing in on non-static, non-inlined API entrypoints or functions. I'll need to check the obvious: `init_module` (or possibly the `__x64_sys_init_module` variations), `finit_module` , `codetag_alloc_module_section`, and `codetag_free_module_sections`. These are the obvious entry points. I should also check standard symbol names in `kernel/module/main.c` and `lib/codetag.c` as well. I'll also look at anything related to relocation, such as `apply_relocate_add`. I can probably use `nm` or Syzkaller's targeting methods to zero in on these symbols in the kernel code. Let's make sure I find anything in `kernel/module/main.c` that's not static.

26/2 2026/09/03 00:29 tool grepper
0m Args: 
{
  "Expression": "^[^ \\t#\\/].*\\)",
  "PathPrefix": "kernel/module/"
}

Results: 
{
  "Output": "\nFull output is too long, showing 500 out of 5391 lines.\nUse more precise expression if possible.\n\nkernel/module/Kconfig=2=menuconfig MODULES\n--\nkernel/module/Kconfig-9-\t  permanently built into the kernel.  You use the \"modprobe\"\nkernel/module/Kconfig:10:\t  tool to add (and sometimes remove) them.  If you say Y here,\nkernel/module/Kconfig-11-\t  many parts of the kernel can be built as modules (by\nkernel/module/Kconfig:12:\t  answering M instead of Y where indicated): this is most\nkernel/module/Kconfig-13-\t  useful for infrequently used options which are not required\n--\nkernel/module/Kconfig-19-\t  where modprobe can find them (you may need to be root to do\nkernel/module/Kconfig:20:\t  this).\nkernel/module/Kconfig-21-\n--\nkernel/module/Kconfig=63=config MODULE_DEBUG_AUTOLOAD_DUPS\n--\nkernel/module/Kconfig-66-\t  Module autoloading allows in-kernel code to request modules through\nkernel/module/Kconfig:67:\t  the *request_module*() API calls. This in turn just calls userspace\nkernel/module/Kconfig-68-\t  modprobe. Although modprobe checks to see if a module is already\n--\nkernel/module/Kconfig-70-\t  which multiple duplicate requests can end up in userspace and multiple\nkernel/module/Kconfig:71:\t  modprobe calls race calling finit_module() around the same time for\nkernel/module/Kconfig:72:\t  duplicate modules. The finit_module() system call can consume in the\nkernel/module/Kconfig-73-\t  worst case more than twice the respective module size in virtual\n--\nkernel/module/Kconfig-78-\nkernel/module/Kconfig:79:\t  This debugging facility will create pr_warn() splats for duplicate\nkernel/module/Kconfig-80-\t  module requests to help identify if module auto-loading may be the\n--\nkernel/module/Kconfig-84-\t  requests for the same module to a single request. You can boot with\nkernel/module/Kconfig:85:\t  the module.enable_dups_trace=1 kernel parameter to use WARN_ON()\nkernel/module/Kconfig:86:\t  instead of the pr_warn().\nkernel/module/Kconfig-87-\nkernel/module/Kconfig:88:\t  If the first module request used request_module_nowait() we cannot\nkernel/module/Kconfig-89-\t  use that as the anchor to wait for duplicate module requests, since\nkernel/module/Kconfig:90:\t  users of request_module() do want a proper return value. If a call\nkernel/module/Kconfig:91:\t  for the same module happened earlier with request_module() though,\nkernel/module/Kconfig:92:\t  then a duplicate request_module_nowait() would be detected. The\nkernel/module/Kconfig:93:\t  non-wait request_module() call is synchronous and waits until modprobe\nkernel/module/Kconfig-94-\t  completes. Subsequent auto-loading requests for the same module do\nkernel/module/Kconfig:95:\t  not trigger a new finit_module() calls and do not strain virtual\nkernel/module/Kconfig-96-\t  memory, and so as soon as modprobe successfully completes we remove\n--\nkernel/module/Kconfig-102-\t  abuse was due to module auto-loading. These issues are currently only\nkernel/module/Kconfig:103:\t  known to occur on systems with many CPUs (over 400) and is likely the\nkernel/module/Kconfig-104-\t  result of udev issuing duplicate module requests for each CPU, and so\n--\nkernel/module/Kconfig=112=config MODULE_DEBUG_AUTOLOAD_DUPS_TRACE\n--\nkernel/module/Kconfig-116-\t  Enabling this will force a full stack trace for duplicate module\nkernel/module/Kconfig:117:\t  auto-loading requests using WARN_ON() instead of pr_warn(). You\nkernel/module/Kconfig-118-\t  should keep this disabled at all times unless you are a developer\n--\nkernel/module/Kconfig=124=config MODULE_FORCE_LOAD\n--\nkernel/module/Kconfig-128-\t  Allow loading of modules without version information (ie. modprobe\nkernel/module/Kconfig:129:\t  --force).  Forced module loading sets the 'F' (forced) taint flag and\nkernel/module/Kconfig-130-\t  is usually a really bad idea.\n--\nkernel/module/Kconfig=132=config MODULE_UNLOAD\n--\nkernel/module/Kconfig-136-\t  modules (note that some modules may not be unloadable\nkernel/module/Kconfig:137:\t  anyway), which makes your kernel smaller, faster\nkernel/module/Kconfig-138-\t  and simpler.  If unsure, say Y.\n--\nkernel/module/Kconfig=140=config MODULE_FORCE_UNLOAD\n--\nkernel/module/Kconfig-146-\t  without waiting for anyone to stop using it (using the -f option to\nkernel/module/Kconfig:147:\t  rmmod).  This is mainly for kernel developers and desperate users.\nkernel/module/Kconfig-148-\t  If unsure, say N.\n--\nkernel/module/Kconfig=150=config MODULE_UNLOAD_TAINT_TRACKING\n--\nkernel/module/Kconfig-156-\t  module that tainted the kernel. In addition to displaying a\nkernel/module/Kconfig:157:\t  list of linked (or loaded) modules e.g. on detection of a bad\nkernel/module/Kconfig:158:\t  page (see bad_page()), the aforementioned details are also\nkernel/module/Kconfig-159-\t  shown. If unsure, say N.\n--\nkernel/module/Kconfig=161=config MODVERSIONS\n--\nkernel/module/Kconfig-167-\t  compiled for different kernels, by adding enough information\nkernel/module/Kconfig:168:\t  to the modules to (hopefully) spot any changes which would\nkernel/module/Kconfig-169-\t  make them incompatible with the kernel you are running.  If\n--\nkernel/module/Kconfig=181=config GENKSYMS\nkernel/module/Kconfig:182:\tbool \"genksyms (from source code)\"\nkernel/module/Kconfig-183-\thelp\n--\nkernel/module/Kconfig=189=config GENDWARFKSYMS\nkernel/module/Kconfig:190:\tbool \"gendwarfksyms (from debugging information)\"\nkernel/module/Kconfig-191-\tdepends on DEBUG_INFO\n--\nkernel/module/Kconfig-197-\t# X86, requires pahole before commit 47dcb534e253 (\"btf_encoder: Stop\nkernel/module/Kconfig:198:\t# indexing symbols for VARs\") or after commit 9810758003ce (\"btf_encoder:\nkernel/module/Kconfig:199:\t# Verify 0 address DWARF variables are in ELF section\").\nkernel/module/Kconfig-200-\tdepends on !X86 || !DEBUG_INFO_BTF || PAHOLE_VERSION \u003c 128 || PAHOLE_VERSION \u003e 129\n--\nkernel/module/Kconfig=241=config MODULE_SRCVERSION_ALL\n--\nkernel/module/Kconfig-248-\t  others sometimes change the module source without updating\nkernel/module/Kconfig:249:\t  the version).  With this option, such a \"srcversion\" field\nkernel/module/Kconfig-250-\t  will be created for all modules.  If unsure, say N.\n--\nkernel/module/Kconfig=252=config MODULE_SIG\n--\nkernel/module/Kconfig-270-\t  module DOES NOT get stripped after being signed.  This includes the\nkernel/module/Kconfig:271:\t  debuginfo strip done by some packagers (such as rpmbuild) and\nkernel/module/Kconfig-272-\t  inclusion into an initramfs that wants the module size reduced.\n--\nkernel/module/Kconfig=406=config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS\n--\nkernel/module/Kconfig-408-\thelp\nkernel/module/Kconfig:409:\t  Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in\nkernel/module/Kconfig-410-\t  a namespace. A module that makes use of a symbol exported with such a\nkernel/module/Kconfig:411:\t  namespace is required to import the namespace via MODULE_IMPORT_NS(\"\").\nkernel/module/Kconfig-412-\t  There is no technical reason to enforce correct namespace imports,\n--\nkernel/module/Kconfig=419=config MODPROBE_PATH\n--\nkernel/module/Kconfig-428-\t  removes the kernel's ability to request modules (but\nkernel/module/Kconfig:429:\t  userspace can still load modules explicitly).\nkernel/module/Kconfig-430-\nkernel/module/Kconfig=431=config TRIM_UNUSED_KSYMS\n--\nkernel/module/Kconfig-434-\t  The kernel and some modules make many symbols available for\nkernel/module/Kconfig:435:\t  other modules to use via EXPORT_SYMBOL() and variants. Depending\nkernel/module/Kconfig-436-\t  on the set of modules being selected in your kernel configuration,\n--\nkernel/module/Kconfig-440-\t  the build. In turn, this provides the compiler more opportunities\nkernel/module/Kconfig:441:\t  (especially when using LTO) for optimizing the code and reducing\nkernel/module/Kconfig-442-\t  binary size.  This might have some security advantages as well.\n--\nkernel/module/Makefile=12=obj-y += kmod.o\nkernel/module/Makefile:13:obj-$(CONFIG_MODULE_DEBUG_AUTOLOAD_DUPS) += dups.o\nkernel/module/Makefile:14:obj-$(CONFIG_MODULE_DECOMPRESS) += decompress.o\nkernel/module/Makefile:15:obj-$(CONFIG_MODULE_SIG) += signing.o\nkernel/module/Makefile:16:obj-$(CONFIG_LIVEPATCH) += livepatch.o\nkernel/module/Makefile:17:obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o\nkernel/module/Makefile:18:obj-$(CONFIG_DEBUG_KMEMLEAK) += debug_kmemleak.o\nkernel/module/Makefile:19:obj-$(CONFIG_KALLSYMS) += kallsyms.o\nkernel/module/Makefile:20:obj-$(CONFIG_PROC_FS) += procfs.o\nkernel/module/Makefile:21:obj-$(CONFIG_SYSFS) += sysfs.o\nkernel/module/Makefile:22:obj-$(CONFIG_KGDB_KDB) += kdb.o\nkernel/module/Makefile:23:obj-$(CONFIG_MODVERSIONS) += version.o\nkernel/module/Makefile:24:obj-$(CONFIG_MODULE_UNLOAD_TAINT_TRACKING) += tracking.o\nkernel/module/Makefile:25:obj-$(CONFIG_MODULE_STATS) += stats.o\n--\nkernel/module/debug_kmemleak.c=12=void kmemleak_load_module(const struct module *mod,\nkernel/module/debug_kmemleak.c:13:\t\t\t  const struct load_info *info)\nkernel/module/debug_kmemleak.c-14-{\nkernel/module/debug_kmemleak.c-15-\t/* only scan writable, non-executable sections */\nkernel/module/debug_kmemleak.c:16:\tfor_each_mod_mem_type(type) {\nkernel/module/debug_kmemleak.c-17-\t\tif (type != MOD_DATA \u0026\u0026 type != MOD_INIT_DATA \u0026\u0026\nkernel/module/debug_kmemleak.c:18:\t\t    !mod-\u003emem[type].is_rox)\nkernel/module/debug_kmemleak.c:19:\t\t\tkmemleak_no_scan(mod-\u003emem[type].base);\nkernel/module/debug_kmemleak.c-20-\t}\n--\nkernel/module/decompress.c-16-\nkernel/module/decompress.c:17:static int module_extend_max_pages(struct load_info *info, unsigned int extent)\nkernel/module/decompress.c-18-{\n--\nkernel/module/decompress.c-22-\tnew_pages = kvrealloc(info-\u003epages,\nkernel/module/decompress.c:23:\t\t\t      size_mul(new_max, sizeof(*info-\u003epages)),\nkernel/module/decompress.c:24:\t\t\t      GFP_KERNEL);\nkernel/module/decompress.c:25:\tif (!new_pages)\nkernel/module/decompress.c-26-\t\treturn -ENOMEM;\n--\nkernel/module/decompress.c-33-\nkernel/module/decompress.c:34:static struct page *module_get_next_page(struct load_info *info)\nkernel/module/decompress.c-35-{\n--\nkernel/module/decompress.c-38-\nkernel/module/decompress.c:39:\tif (info-\u003emax_pages == info-\u003eused_pages) {\nkernel/module/decompress.c:40:\t\terror = module_extend_max_pages(info, info-\u003eused_pages);\nkernel/module/decompress.c:41:\t\tif (error)\nkernel/module/decompress.c:42:\t\t\treturn ERR_PTR(error);\nkernel/module/decompress.c-43-\t}\nkernel/module/decompress.c-44-\nkernel/module/decompress.c:45:\tpage = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);\nkernel/module/decompress.c:46:\tif (!page)\nkernel/module/decompress.c:47:\t\treturn ERR_PTR(-ENOMEM);\nkernel/module/decompress.c-48-\n--\nkernel/module/decompress.c-62- */\nkernel/module/decompress.c:63:static size_t module_gzip_header_len(const u8 *buf, size_t size)\nkernel/module/decompress.c-64-{\n--\nkernel/module/decompress.c-67-\nkernel/module/decompress.c:68:\tif (size \u003c len || memcmp(buf, signature, sizeof(signature)))\nkernel/module/decompress.c-69-\t\treturn 0;\nkernel/module/decompress.c-70-\nkernel/module/decompress.c:71:\tif (buf[3] \u0026 0x08) {\nkernel/module/decompress.c-72-\t\tdo {\n--\nkernel/module/decompress.c-76-\t\t\t */\nkernel/module/decompress.c:77:\t\t\tif (len == size)\nkernel/module/decompress.c-78-\t\t\t\treturn 0;\nkernel/module/decompress.c:79:\t\t} while (buf[len++] != '\\0');\nkernel/module/decompress.c-80-\t}\n--\nkernel/module/decompress.c=85=static ssize_t module_gzip_decompress(struct load_info *info,\nkernel/module/decompress.c:86:\t\t\t\t      const void *buf, size_t size)\nkernel/module/decompress.c-87-{\n--\nkernel/module/decompress.c-93-\nkernel/module/decompress.c:94:\tgzip_hdr_len = module_gzip_header_len(buf, size);\nkernel/module/decompress.c:95:\tif (!gzip_hdr_len) {\nkernel/module/decompress.c:96:\t\tpr_err(\"not a gzip compressed module\\n\");\nkernel/module/decompress.c-97-\t\treturn -EINVAL;\n--\nkernel/module/decompress.c-102-\nkernel/module/decompress.c:103:\ts.workspace = kvmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);\nkernel/module/decompress.c:104:\tif (!s.workspace)\nkernel/module/decompress.c-105-\t\treturn -ENOMEM;\nkernel/module/decompress.c-106-\nkernel/module/decompress.c:107:\trc = zlib_inflateInit2(\u0026s, -MAX_WBITS);\nkernel/module/decompress.c:108:\tif (rc != Z_OK) {\nkernel/module/decompress.c:109:\t\tpr_err(\"failed to initialize decompressor: %d\\n\", rc);\nkernel/module/decompress.c-110-\t\tretval = -EINVAL;\n--\nkernel/module/decompress.c-114-\tdo {\nkernel/module/decompress.c:115:\t\tstruct page *page = module_get_next_page(info);\nkernel/module/decompress.c-116-\nkernel/module/decompress.c:117:\t\tif (IS_ERR(page)) {\nkernel/module/decompress.c:118:\t\t\tretval = PTR_ERR(page);\nkernel/module/decompress.c-119-\t\t\tgoto out_inflate_end;\n--\nkernel/module/decompress.c-121-\nkernel/module/decompress.c:122:\t\ts.next_out = kmap_local_page(page);\nkernel/module/decompress.c-123-\t\ts.avail_out = PAGE_SIZE;\nkernel/module/decompress.c:124:\t\trc = zlib_inflate(\u0026s, 0);\nkernel/module/decompress.c:125:\t\tkunmap_local(s.next_out);\nkernel/module/decompress.c-126-\nkernel/module/decompress.c-127-\t\tnew_size += PAGE_SIZE - s.avail_out;\nkernel/module/decompress.c:128:\t} while (rc == Z_OK);\nkernel/module/decompress.c-129-\nkernel/module/decompress.c:130:\tif (rc != Z_STREAM_END) {\nkernel/module/decompress.c:131:\t\tpr_err(\"decompression failed with status %d\\n\", rc);\nkernel/module/decompress.c-132-\t\tretval = -EINVAL;\n--\nkernel/module/decompress.c-138-out_inflate_end:\nkernel/module/decompress.c:139:\tzlib_inflateEnd(\u0026s);\nkernel/module/decompress.c-140-out:\nkernel/module/decompress.c:141:\tkvfree(s.workspace);\nkernel/module/decompress.c-142-\treturn retval;\n--\nkernel/module/decompress.c=149=static ssize_t module_xz_decompress(struct load_info *info,\nkernel/module/decompress.c:150:\t\t\t\t    const void *buf, size_t size)\nkernel/module/decompress.c-151-{\n--\nkernel/module/decompress.c-158-\nkernel/module/decompress.c:159:\tif (size \u003c sizeof(signature) ||\nkernel/module/decompress.c:160:\t    memcmp(buf, signature, sizeof(signature))) {\nkernel/module/decompress.c:161:\t\tpr_err(\"not an xz compressed module\\n\");\nkernel/module/decompress.c-162-\t\treturn -EINVAL;\n--\nkernel/module/decompress.c-164-\nkernel/module/decompress.c:165:\txz_dec = xz_dec_init(XZ_DYNALLOC, (u32)-1);\nkernel/module/decompress.c:166:\tif (!xz_dec)\nkernel/module/decompress.c-167-\t\treturn -ENOMEM;\n--\nkernel/module/decompress.c-173-\tdo {\nkernel/module/decompress.c:174:\t\tstruct page *page = module_get_next_page(info);\nkernel/module/decompress.c-175-\nkernel/module/decompress.c:176:\t\tif (IS_ERR(page)) {\nkernel/module/decompress.c:177:\t\t\tretval = PTR_ERR(page);\nkernel/module/decompress.c-178-\t\t\tgoto out;\n--\nkernel/module/decompress.c-180-\nkernel/module/decompress.c:181:\t\txz_buf.out = kmap_local_page(page);\nkernel/module/decompress.c-182-\t\txz_buf.out_pos = 0;\nkernel/module/decompress.c-183-\t\txz_buf.out_size = PAGE_SIZE;\nkernel/module/decompress.c:184:\t\txz_ret = xz_dec_run(xz_dec, \u0026xz_buf);\nkernel/module/decompress.c:185:\t\tkunmap_local(xz_buf.out);\nkernel/module/decompress.c-186-\nkernel/module/decompress.c-187-\t\tnew_size += xz_buf.out_pos;\nkernel/module/decompress.c:188:\t} while (xz_buf.out_pos == PAGE_SIZE \u0026\u0026 xz_ret == XZ_OK);\nkernel/module/decompress.c-189-\nkernel/module/decompress.c:190:\tif (xz_ret != XZ_STREAM_END) {\nkernel/module/decompress.c:191:\t\tpr_err(\"decompression failed with status %d\\n\", xz_ret);\nkernel/module/decompress.c-192-\t\tretval = -EINVAL;\n--\nkernel/module/decompress.c-198- out:\nkernel/module/decompress.c:199:\txz_dec_end(xz_dec);\nkernel/module/decompress.c-200-\treturn retval;\n--\nkernel/module/decompress.c=207=static ssize_t module_zstd_decompress(struct load_info *info,\nkernel/module/decompress.c:208:\t\t\t\t    const void *buf, size_t size)\nkernel/module/decompress.c-209-{\n--\nkernel/module/decompress.c-220-\nkernel/module/decompress.c:221:\tif (size \u003c sizeof(signature) ||\nkernel/module/decompress.c:222:\t    memcmp(buf, signature, sizeof(signature))) {\nkernel/module/decompress.c:223:\t\tpr_err(\"not a zstd compressed module\\n\");\nkernel/module/decompress.c-224-\t\treturn -EINVAL;\n--\nkernel/module/decompress.c-230-\nkernel/module/decompress.c:231:\tret = zstd_get_frame_header(\u0026header, zstd_buf.src, zstd_buf.size);\nkernel/module/decompress.c:232:\tif (ret != 0) {\nkernel/module/decompress.c:233:\t\tpr_err(\"ZSTD-compressed data has an incomplete frame header\\n\");\nkernel/module/decompress.c-234-\t\tretval = -EINVAL;\n--\nkernel/module/decompress.c-236-\t}\nkernel/module/decompress.c:237:\tif (header.windowSize \u003e (1 \u003c\u003c ZSTD_WINDOWLOG_MAX)) {\nkernel/module/decompress.c:238:\t\tpr_err(\"ZSTD-compressed data has too large a window size\\n\");\nkernel/module/decompress.c-239-\t\tretval = -EINVAL;\n--\nkernel/module/decompress.c-242-\nkernel/module/decompress.c:243:\twksp_size = zstd_dstream_workspace_bound(header.windowSize);\nkernel/module/decompress.c:244:\twksp = kvmalloc(wksp_size, GFP_KERNEL);\nkernel/module/decompress.c:245:\tif (!wksp) {\nkernel/module/decompress.c-246-\t\tretval = -ENOMEM;\n--\nkernel/module/decompress.c-249-\nkernel/module/decompress.c:250:\tdstream = zstd_init_dstream(header.windowSize, wksp, wksp_size);\nkernel/module/decompress.c:251:\tif (!dstream) {\nkernel/module/decompress.c:252:\t\tpr_err(\"Can't initialize ZSTD stream\\n\");\nkernel/module/decompress.c-253-\t\tretval = -ENOMEM;\n--\nkernel/module/decompress.c-257-\tdo {\nkernel/module/decompress.c:258:\t\tstruct page *page = module_get_next_page(info);\nkernel/module/decompress.c-259-\nkernel/module/decompress.c:260:\t\tif (IS_ERR(page)) {\nkernel/module/decompress.c:261:\t\t\tretval = PTR_ERR(page);\nkernel/module/decompress.c-262-\t\t\tgoto out;\n--\nkernel/module/decompress.c-264-\nkernel/module/decompress.c:265:\t\tzstd_dec.dst = kmap_local_page(page);\nkernel/module/decompress.c-266-\t\tzstd_dec.pos = 0;\n--\nkernel/module/decompress.c-268-\nkernel/module/decompress.c:269:\t\tret = zstd_decompress_stream(dstream, \u0026zstd_dec, \u0026zstd_buf);\nkernel/module/decompress.c:270:\t\tkunmap_local(zstd_dec.dst);\nkernel/module/decompress.c:271:\t\tretval = zstd_get_error_code(ret);\nkernel/module/decompress.c:272:\t\tif (retval)\nkernel/module/decompress.c-273-\t\t\tbreak;\n--\nkernel/module/decompress.c-275-\t\tnew_size += zstd_dec.pos;\nkernel/module/decompress.c:276:\t} while (zstd_dec.pos == PAGE_SIZE \u0026\u0026 ret != 0);\nkernel/module/decompress.c-277-\nkernel/module/decompress.c:278:\tif (retval) {\nkernel/module/decompress.c:279:\t\tpr_err(\"ZSTD-decompression failed with status %d\\n\", retval);\nkernel/module/decompress.c-280-\t\tretval = -EINVAL;\n--\nkernel/module/decompress.c-286- out:\nkernel/module/decompress.c:287:\tkvfree(wksp);\nkernel/module/decompress.c-288-\treturn retval;\n--\nkernel/module/decompress.c-293-\nkernel/module/decompress.c:294:int module_decompress(struct load_info *info, const void *buf, size_t size)\nkernel/module/decompress.c-295-{\n--\nkernel/module/decompress.c-307-\t */\nkernel/module/decompress.c:308:\tn_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2;\nkernel/module/decompress.c:309:\terror = module_extend_max_pages(info, n_pages);\nkernel/module/decompress.c:310:\tif (error)\nkernel/module/decompress.c-311-\t\treturn error;\nkernel/module/decompress.c-312-\nkernel/module/decompress.c:313:\tdata_size = MODULE_DECOMPRESS_FN(info, buf, size);\nkernel/module/decompress.c:314:\tif (data_size \u003c 0) {\nkernel/module/decompress.c-315-\t\terror = data_size;\n--\nkernel/module/decompress.c-318-\nkernel/module/decompress.c:319:\tinfo-\u003ehdr = vmap(info-\u003epages, info-\u003eused_pages, VM_MAP, PAGE_KERNEL);\nkernel/module/decompress.c:320:\tif (!info-\u003ehdr) {\nkernel/module/decompress.c-321-\t\terror = -ENOMEM;\n--\nkernel/module/decompress.c-328-err:\nkernel/module/decompress.c:329:\tmodule_decompress_cleanup(info);\nkernel/module/decompress.c-330-\treturn error;\n--\nkernel/module/decompress.c-332-\nkernel/module/decompress.c:333:void module_decompress_cleanup(struct load_info *info)\nkernel/module/decompress.c-334-{\n--\nkernel/module/decompress.c-336-\nkernel/module/decompress.c:337:\tif (info-\u003ehdr)\nkernel/module/decompress.c:338:\t\tvunmap(info-\u003ehdr);\nkernel/module/decompress.c-339-\nkernel/module/decompress.c:340:\tfor (i = 0; i \u003c info-\u003eused_pages; i++)\nkernel/module/decompress.c:341:\t\t__free_page(info-\u003epages[i]);\nkernel/module/decompress.c-342-\nkernel/module/decompress.c:343:\tkvfree(info-\u003epages);\nkernel/module/decompress.c-344-\n--\nkernel/module/decompress.c=350=static ssize_t compression_show(struct kobject *kobj,\nkernel/module/decompress.c:351:\t\t\t\tstruct kobj_attribute *attr, char *buf)\nkernel/module/decompress.c-352-{\nkernel/module/decompress.c:353:\treturn sysfs_emit(buf, __stringify(MODULE_COMPRESSION) \"\\n\");\nkernel/module/decompress.c-354-}\nkernel/module/decompress.c-355-\nkernel/module/decompress.c:356:static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);\nkernel/module/decompress.c-357-\nkernel/module/decompress.c:358:static int __init module_decompress_sysfs_init(void)\nkernel/module/decompress.c-359-{\n--\nkernel/module/decompress.c-362-\terror = sysfs_create_file(\u0026module_kset-\u003ekobj,\nkernel/module/decompress.c:363:\t\t\t\t  \u0026module_compression_attr.attr);\nkernel/module/decompress.c:364:\tif (error)\nkernel/module/decompress.c:365:\t\tpr_warn(\"Failed to create 'compression' attribute\");\nkernel/module/decompress.c-366-\n--\nkernel/module/decompress.c-368-}\nkernel/module/decompress.c:369:late_initcall(module_decompress_sysfs_init);\nkernel/module/decompress.c-370-#endif\n--\nkernel/module/dups.c-30-#define MODULE_PARAM_PREFIX \"module.\"\nkernel/module/dups.c:31:static bool enable_dups_trace = IS_ENABLED(CONFIG_MODULE_DEBUG_AUTOLOAD_DUPS_TRACE);\nkernel/module/dups.c:32:module_param(enable_dups_trace, bool_enable_only, 0644);\nkernel/module/dups.c-33-\nkernel/module/dups.c-34-/* A mutex-protected list of active kmod requests. */\nkernel/module/dups.c:35:static DEFINE_MUTEX(kmod_dup_mutex);\nkernel/module/dups.c:36:static LIST_HEAD(dup_kmod_reqs);\nkernel/module/dups.c-37-\nkernel/module/dups.c=38=struct kmod_dup_req {\n--\nkernel/module/dups.c-46-\nkernel/module/dups.c:47:static void get_kmod_req(struct kmod_dup_req *kmod_req)\nkernel/module/dups.c-48-{\nkernel/module/dups.c:49:\trefcount_inc(\u0026kmod_req-\u003erefcount);\nkernel/module/dups.c-50-}\nkernel/module/dups.c-51-\nkernel/module/dups.c:52:static void put_kmod_req(struct kmod_dup_req *kmod_req)\nkernel/module/dups.c-53-{\nkernel/module/dups.c:54:\tif (refcount_dec_and_test(\u0026kmod_req-\u003erefcount))\nkernel/module/dups.c:55:\t\tkfree(kmod_req);\nkernel/module/dups.c-56-}\nkernel/module/dups.c-57-\nkernel/module/dups.c:58:DEFINE_FREE(put_kmod_req, struct kmod_dup_req *, if (_T) put_kmod_req(_T))\nkernel/module/dups.c-59-\nkernel/module/dups.c:60:static struct kmod_dup_req *kmod_dup_request_lookup(char *module_name)\nkernel/module/dups.c-61-{\n--\nkernel/module/dups.c-63-\nkernel/module/dups.c:64:\tlockdep_assert_held(\u0026kmod_dup_mutex);\nkernel/module/dups.c-65-\nkernel/module/dups.c:66:\tlist_for_each_entry(kmod_req, \u0026dup_kmod_reqs, list) {\nkernel/module/dups.c:67:\t\tif (!strcmp(kmod_req-\u003ename, module_name))\nkernel/module/dups.c-68-\t\t\treturn kmod_req;\n--\nkernel/module/dups.c-73-\nkernel/module/dups.c:74:static void kmod_dup_request_delete(struct work_struct *work)\nkernel/module/dups.c-75-{\nkernel/module/dups.c-76-\tstruct kmod_dup_req *kmod_req;\nkernel/module/dups.c:77:\tkmod_req = container_of(to_delayed_work(work), struct kmod_dup_req, delete_work);\nkernel/module/dups.c-78-\n--\nkernel/module/dups.c-83-\t * module is loaded so will just return 0 right away. There is still\nkernel/module/dups.c:84:\t * a small chance right after we delete this entry new request_module()\nkernel/module/dups.c-85-\t * calls may happen after that, they can happen. These heuristics\nkernel/module/dups.c:86:\t * are to protect finit_module() abuse for auto-loading, if modules\nkernel/module/dups.c-87-\t * are still tryign to auto-load even if a module is already loaded,\n--\nkernel/module/dups.c-91-\t */\nkernel/module/dups.c:92:\tscoped_guard(mutex, \u0026kmod_dup_mutex)\nkernel/module/dups.c:93:\t\tlist_del(\u0026kmod_req-\u003elist);\nkernel/module/dups.c-94-\nkernel/module/dups.c:95:\tput_kmod_req(kmod_req);\nkernel/module/dups.c-96-}\nkernel/module/dups.c-97-\nkernel/module/dups.c:98:static struct kmod_dup_req *alloc_kmod_req(const char *module_name)\nkernel/module/dups.c-99-{\nkernel/module/dups.c:100:\tstruct kmod_dup_req *kmod_req = kzalloc_obj(*kmod_req);\nkernel/module/dups.c-101-\nkernel/module/dups.c:102:\tif (!kmod_req)\nkernel/module/dups.c-103-\t\treturn NULL;\nkernel/module/dups.c-104-\nkernel/module/dups.c:105:\trefcount_set(\u0026kmod_req-\u003erefcount, 1);\nkernel/module/dups.c:106:\tstrscpy(kmod_req-\u003ename, module_name);\nkernel/module/dups.c:107:\tINIT_DELAYED_WORK(\u0026kmod_req-\u003edelete_work, kmod_dup_request_delete);\nkernel/module/dups.c:108:\tinit_completion(\u0026kmod_req-\u003efirst_req_done);\nkernel/module/dups.c-109-\treturn kmod_req;\n--\nkernel/module/dups.c-111-\nkernel/module/dups.c:112:bool kmod_dup_request_exists_wait(char *module_name, bool wait, int *dup_ret)\nkernel/module/dups.c-113-{\nkernel/module/dups.c:114:\tstruct kmod_dup_req *kmod_req __free(put_kmod_req) = NULL;\nkernel/module/dups.c-115-\tint ret;\nkernel/module/dups.c-116-\nkernel/module/dups.c:117:\tscoped_guard(mutex, \u0026kmod_dup_mutex) {\nkernel/module/dups.c-118-\t\tstruct kmod_dup_req *new_kmod_req;\nkernel/module/dups.c-119-\nkernel/module/dups.c:120:\t\tkmod_req = kmod_dup_request_lookup(module_name);\nkernel/module/dups.c:121:\t\tif (kmod_req) {\nkernel/module/dups.c:122:\t\t\tget_kmod_req(kmod_req);\nkernel/module/dups.c-123-\t\t\tbreak;\n--\nkernel/module/dups.c-127-\t\t * If the first request that came through for a module\nkernel/module/dups.c:128:\t\t * was with request_module_nowait() we cannot wait for it\nkernel/module/dups.c-129-\t\t * and share its return value with other users which may\nkernel/module/dups.c:130:\t\t * have used request_module() and need a proper return value\nkernel/module/dups.c-131-\t\t * so just skip using them as an anchor.\n--\nkernel/module/dups.c-133-\t\t * If a prior request to this one came through with\nkernel/module/dups.c:134:\t\t * request_module() though, then a request_module_nowait()\nkernel/module/dups.c-135-\t\t * would benefit from duplicate detection.\nkernel/module/dups.c-136-\t\t */\nkernel/module/dups.c:137:\t\tif (!wait) {\nkernel/module/dups.c:138:\t\t\tpr_debug(\"New request_module_nowait() for %s -- cannot track duplicates for this request\\n\", module_name);\nkernel/module/dups.c-139-\t\t\treturn false;\n--\nkernel/module/dups.c-145-\t\t */\n\n"
}
27/2 2026/09/03 00:29 llm patch-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 28899
							output: 146
							thoughts: 555

Thoughts: 
**Fuzzing Target Assessment: Kernel Module Loading and Memory Management**

Okay, let's break this down. First, I see the core functions affected are primarily within `kernel/module/main.c`—functions like `init_module`, `finit_module`, and `delete_module`—along with `lib/codetag.c`, specifically related to codetag allocation (`codetag_alloc_module_section`, `codetag_free_module_sections`, and `codetag_needs_module_section`). This points to direct manipulation of ELF module parsing and module lifecycle.

Next, I need to confirm the configurations. `MODULES` is a given, essential for module loading. However, the critical one here is `MEM_ALLOC_PROFILING`. That's where things get interesting, because it brings in alloc_tag codetag support, thus `CODE_TAGGING`, `PAGE_EXTENSION`, and `SLAB_OBJ_EXT`. I'll cross-reference `mm/Kconfig.debug` and confirm that `MEM_ALLOC_PROFILING` depends on `MMU` and `PROC_FS`.

Now, digging into the `WorthFuzzing` assessment: the changes touch core kernel memory management and module loading logic. Specifically, how ELF sections are handled, and the relocation of codetags and per-cpu sections is crucial. The modifications encompass functions involved in ELF section layout (`__layout_sections`, `move_module`, `allocate_codetag_sections`, and `layout_and_allocate`) which relates to how codetags and per-cpu sections are tracked and relocated during module loading. Memory reservation and release via `alloc_tag.c`, and the fallback handling if tags aren't addressable, which are key during loading and unloading.

This directly implicates how ELF modules are parsed, memory allocated, and initialized/cleaned up when a module loads. `init_module` and `finit_module` are involved in the process, which is a prime target for fuzzing.

Therefore, this is *absolutely* worth fuzzing. I'll flag `WorthFuzzing` as `true` and the reasoning is concise: We're dealing with modifications to core kernel memory management and module loading logic, especially concerning the handling of ELF sections and codetags during module lifecycle.

The key symbols to focus on are: `init_module`, `finit_module`, `codetag_alloc_module_section`, and `codetag_free_module_sections`.

The necessary configuration options are `MODULES` and `MEM_ALLOC_PROFILING`.

I've verified everything – it's all accurate and consistent. Time to set the results.

28/2 2026/09/03 00:30 tool set-results
0m Args: 
{
  "EnableConfigs": [
    "MODULES",
    "MEM_ALLOC_PROFILING"
  ],
  "FocusSymbols": [
    "init_module",
    "finit_module",
    "codetag_alloc_module_section",
    "codetag_free_module_sections"
  ],
  "Reasoning": "The patch changes core kernel module loading and layout logic for standalone sections (per-CPU sections and codetags/alloc tags) as well as memory allocation profiling tag reservation fallback handling when tags are not addressable. These changes are reachable via module loading syscalls (init_module and finit_module) and are worth fuzzing.",
  "WorthFuzzing": true
}

Results: 
{
  "EnableConfigs": [
    "MODULES",
    "MEM_ALLOC_PROFILING"
  ],
  "FocusSymbols": [
    "init_module",
    "finit_module",
    "codetag_alloc_module_section",
    "codetag_free_module_sections"
  ],
  "Reasoning": "The patch changes core kernel module loading and layout logic for standalone sections (per-CPU sections and codetags/alloc tags) as well as memory allocation profiling tag reservation fallback handling when tags are not addressable. These changes are reachable via module loading syscalls (init_module and finit_module) and are worth fuzzing.",
  "WorthFuzzing": true
}
29/1 2026/09/03 00:30 action If
0m Args: 
{
  "WorthFuzzing": true
}

Results: 
null
30/2 2026/09/03 00:30 agent kmsan-evaluator
0m Model: 
core

Args: 
null

Results: 
{
  "KMSANReasoning": "The patch refactors the ELF section layout and allocation logic for standalone module sections (such as per-CPU sections and codetag/alloc_tag sections) during module loading in `kernel/module/main.c` and adjusts error handling in `mm/alloc_tag.c`.\n\nKMSAN vs KASAN analysis:\n- KMSAN detects reads of uninitialized memory and information leaks to user space. The patch does not introduce uninitialized stack or heap variables, does not leave structure paddings uninitialized, does not expose data to user space, and does not introduce branches on uninitialized state. The section data copied via `memcpy()` originates from already-loaded ELF image buffers.\n- Any potential memory management issues introduced by changes to section layouts, relocations, or separate memory allocations (such as out-of-bounds section reads/writes, buffer overflows, or use-after-free conditions) are addressable errors that are detected by standard KASAN.\n\nTherefore, dedicated KMSAN fuzzing is not required.",
  "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: 
For your convenience, here is the diff of the changes:
commit 9d7114f89f2af78fead39760e3cefbca211a249e
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Sep 3 00:29:06 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/linux/module.h b/include/linux/module.h
index 96cc98568eea5..0c6f32ddcbf2d 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -325,6 +325,8 @@ enum mod_mem_type {
 	MOD_INIT_RODATA,
 
 	MOD_MEM_NUM_TYPES,
+
+	MOD_STANDALONE = -2,
 	MOD_INVALID = -1,
 };
 
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 061161cc79d90..4c738074a27b8 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -29,6 +29,14 @@
 #define SH_ENTSIZE_TYPE_MASK	((1UL << SH_ENTSIZE_TYPE_BITS) - 1)
 #define SH_ENTSIZE_OFFSET_MASK	((1UL << (BITS_PER_LONG - SH_ENTSIZE_TYPE_BITS)) - 1)
 
+/*
+ * Marker for sections with a separate allocation, which are not placed
+ * into mod->mem[].
+ */
+#define SH_ENTSIZE_STANDALONE					\
+	(((unsigned long)MOD_STANDALONE & SH_ENTSIZE_TYPE_MASK)	\
+	 << SH_ENTSIZE_TYPE_SHIFT)
+
 /* Maximum number of characters written by module_flags() */
 #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
 
diff --git a/kernel/module/main.c b/kernel/module/main.c
index c1b34dc1e89ac..760449ddab224 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1617,14 +1617,8 @@ static int apply_relocations(struct module *mod, const struct load_info *info)
 		if (infosec >= info->hdr->e_shnum)
 			continue;
 
-		/*
-		 * Don't bother with non-allocated sections.
-		 * An exception is the percpu section, which has separate allocations
-		 * for individual CPUs. We relocate the percpu section in the initial
-		 * ELF template and subsequently copy it to the per-CPU destinations.
-		 */
-		if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC) &&
-		    (!infosec || infosec != info->index.pcpu))
+		/* Don't bother with non-allocated sections. */
+		if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC))
 			continue;
 
 		if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH)
@@ -1715,27 +1709,13 @@ static void __layout_sections(struct module *mod, struct load_info *info, bool i
 
 			if ((s->sh_flags & masks[m][0]) != masks[m][0]
 			    || (s->sh_flags & masks[m][1])
-			    || s->sh_entsize != ~0UL
+			    || s->sh_entsize != ~0UL /* offset or standalone */
 			    || is_init != module_init_layout_section(sname))
 				continue;
 
 			if (WARN_ON_ONCE(type == MOD_INVALID))
 				continue;
 
-			/*
-			 * Do not allocate codetag memory as we load it into
-			 * preallocated contiguous memory.
-			 */
-			if (codetag_needs_module_section(mod, sname, s->sh_size)) {
-				/*
-				 * s->sh_entsize won't be used but populate the
-				 * type field to avoid confusion.
-				 */
-				s->sh_entsize = ((unsigned long)(type) & SH_ENTSIZE_TYPE_MASK)
-						<< SH_ENTSIZE_TYPE_SHIFT;
-				continue;
-			}
-
 			s->sh_entsize = module_get_offset_and_type(mod, type, s, i);
 			pr_debug("\t%s\n", sname);
 		}
@@ -1745,16 +1725,10 @@ static void __layout_sections(struct module *mod, struct load_info *info, bool i
 /*
  * Lay out the SHF_ALLOC sections in a way not dissimilar to how ld
  * might -- code, read-only data, read-write data, small data.  Tally
- * sizes, and place the offsets into sh_entsize fields: high bit means it
- * belongs in init.
+ * sizes, and place the offsets into sh_entsize fields.
  */
 static void layout_sections(struct module *mod, struct load_info *info)
 {
-	unsigned int i;
-
-	for (i = 0; i < info->hdr->e_shnum; i++)
-		info->sechdrs[i].sh_entsize = ~0UL;
-
 	pr_debug("Core section allocation order for %s:\n", mod->name);
 	__layout_sections(mod, info, false);
 
@@ -2800,7 +2774,6 @@ static int move_module(struct module *mod, struct load_info *info)
 {
 	int i, ret;
 	enum mod_mem_type t = MOD_MEM_NUM_TYPES;
-	bool codetag_section_found = false;
 
 	for_each_mod_mem_type(type) {
 		if (!mod->mem[type].size) {
@@ -2820,34 +2793,13 @@ static int move_module(struct module *mod, struct load_info *info)
 	for (i = 0; i < info->hdr->e_shnum; i++) {
 		void *dest;
 		Elf_Shdr *shdr = &info->sechdrs[i];
-		const char *sname;
 
-		if (!(shdr->sh_flags & SHF_ALLOC))
+		if (!(shdr->sh_flags & SHF_ALLOC)
+		    || shdr->sh_entsize == SH_ENTSIZE_STANDALONE)
 			continue;
 
-		sname = info->secstrings + shdr->sh_name;
-		/*
-		 * Load codetag sections separately as they might still be used
-		 * after module unload.
-		 */
-		if (codetag_needs_module_section(mod, sname, shdr->sh_size)) {
-			dest = codetag_alloc_module_section(mod, sname, shdr->sh_size,
-					arch_mod_section_prepend(mod, i), shdr->sh_addralign);
-			if (WARN_ON(!dest)) {
-				ret = -EINVAL;
-				goto out_err;
-			}
-			if (IS_ERR(dest)) {
-				ret = PTR_ERR(dest);
-				goto out_err;
-			}
-			codetag_section_found = true;
-		} else {
-			enum mod_mem_type type = shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT;
-			unsigned long offset = shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK;
-
-			dest = mod->mem[type].base + offset;
-		}
+		dest = mod->mem[shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT].base +
+		       (shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK);
 
 		if (shdr->sh_type != SHT_NOBITS) {
 			/*
@@ -2879,8 +2831,6 @@ static int move_module(struct module *mod, struct load_info *info)
 	module_memory_restore_rox(mod);
 	while (t--)
 		module_memory_free(mod, t);
-	if (codetag_section_found)
-		codetag_free_module_sections(mod);
 
 	return ret;
 }
@@ -2951,9 +2901,51 @@ static bool blacklisted(const char *module_name)
 }
 core_param(module_blacklist, module_blacklist, charp, 0400);
 
+/*
+ * Allocate codetag sections separately. They are loaded into preallocated
+ * contiguous memory because they may still be used after the module is
+ * unloaded.
+ *
+ * If the separate allocation overflows, allocate the section normally
+ * so that the module can still be loaded.
+ */
+static int allocate_codetag_sections(struct load_info *info)
+{
+	for (unsigned int i = 1; i < info->hdr->e_shnum; i++) {
+		Elf_Shdr *shdr = &info->sechdrs[i];
+		const char *sname = info->secstrings + shdr->sh_name;
+		void *dest;
+
+		if (!codetag_needs_module_section(info->mod, sname, shdr->sh_size))
+			continue;
+
+		dest = codetag_alloc_module_section(info->mod, sname, shdr->sh_size,
+				arch_mod_section_prepend(info->mod, i), shdr->sh_addralign);
+		if (WARN_ON(!dest)) {
+			codetag_free_module_sections(info->mod);
+			return -EINVAL;
+		}
+		if (dest == ERR_PTR(-EAGAIN))
+			/* Allocate the section as a regular section. */
+			continue;
+		if (IS_ERR(dest)) {
+			codetag_free_module_sections(info->mod);
+			return PTR_ERR(dest);
+		}
+
+		if (shdr->sh_type != SHT_NOBITS)
+			memcpy(dest, (void *)shdr->sh_addr, shdr->sh_size);
+		shdr->sh_addr = (unsigned long)dest;
+		shdr->sh_entsize = SH_ENTSIZE_STANDALONE;
+	}
+
+	return 0;
+}
+
 static struct module *layout_and_allocate(struct load_info *info, int flags)
 {
 	struct module *mod;
+	unsigned int i;
 	int err;
 
 	/* Allow arches to frob section contents and sizes.  */
@@ -2967,8 +2959,13 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
 	if (err < 0)
 		return ERR_PTR(err);
 
+	/* Repurpose sh_entsize to track where each section is allocated. */
+	for (i = 0; i < info->hdr->e_shnum; i++)
+		info->sechdrs[i].sh_entsize = ~0UL;
+
 	/* We will do a special allocation for per-cpu sections later. */
-	info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;
+	if (info->index.pcpu)
+		info->sechdrs[info->index.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;
 
 	/*
 	 * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can
@@ -2977,18 +2974,21 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
 	 */
 	module_mark_ro_after_init(info->hdr, info->sechdrs, info->secstrings);
 
-	/*
-	 * Determine total sizes, and put offsets in sh_entsize.  For now
-	 * this is done generically; there doesn't appear to be any
-	 * special cases for the architectures.
-	 */
+	/* Allow codetag sections to be allocated separately first. */
+	err = allocate_codetag_sections(info);
+	if (err)
+		return ERR_PTR(err);
+
+	/* Determine total sizes and put offsets in sh_entsize. */
 	layout_sections(info->mod, info);
 	layout_symtab(info->mod, info);
 
 	/* Allocate and move to the final place */
 	err = move_module(info->mod, info);
-	if (err)
+	if (err) {
+		codetag_free_module_sections(info->mod);
 		return ERR_PTR(err);
+	}
 
 	/* Module has been copied to its final place now: return it. */
 	mod = (void *)info->sechdrs[info->index.mod].sh_addr;
diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c
index f30ef8dd24c70..8f13369b32ecd 100644
--- a/mm/alloc_tag.c
+++ b/mm/alloc_tag.c
@@ -843,6 +843,52 @@ static int vm_module_tags_populate(void)
 	return 0;
 }
 
+static void release_module_tags(struct module *mod, bool used)
+{
+	MA_STATE(mas, &mod_area_mt, module_tags.size, module_tags.size);
+	struct alloc_tag *start_tag;
+	struct alloc_tag *end_tag;
+	struct module *val;
+
+	mas_lock(&mas);
+	mas_for_each_rev(&mas, val, 0)
+		if (val == mod)
+			break;
+
+	if (!val) /* module not found */
+		goto out;
+
+	if (!used)
+		goto release_area;
+
+	start_tag = (struct alloc_tag *)(module_tags.start_addr + mas.index);
+	end_tag = (struct alloc_tag *)(module_tags.start_addr + mas.last);
+	if (!clean_unused_counters(start_tag, end_tag)) {
+		struct alloc_tag *tag;
+
+		for (tag = start_tag; tag <= end_tag; tag++) {
+			struct alloc_tag_counters counter;
+
+			if (!tag->counters)
+				continue;
+
+			counter = alloc_tag_read(tag);
+			pr_info("%s:%u module %s func:%s has %llu allocated at module unload\n",
+				tag->ct.filename, tag->ct.lineno, tag->ct.modname,
+				tag->ct.function, counter.bytes);
+		}
+	} else {
+		used = false;
+	}
+release_area:
+	mas_store(&mas, used ? &unloaded_mod : NULL);
+	val = mas_prev_range(&mas, 0);
+	if (val == &prepend_mod)
+		mas_store(&mas, NULL);
+out:
+	mas_unlock(&mas);
+}
+
 static void *reserve_module_tags(struct module *mod, unsigned long size,
 				 unsigned int prepend, unsigned long align)
 {
@@ -912,10 +958,12 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,
 		int grow_res;
 
 		module_tags.size = offset + size;
-		if (mem_alloc_profiling_enabled() && !tags_addressable()) {
+		if (!tags_addressable()) {
 			shutdown_mem_profiling(true);
-			pr_warn("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n",
-				mod->name, NR_UNUSED_PAGEFLAG_BITS);
+			pr_warn_once("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n",
+				     mod->name, NR_UNUSED_PAGEFLAG_BITS);
+			release_module_tags(mod, false);
+			return ERR_PTR(-EAGAIN);
 		}
 
 		grow_res = vm_module_tags_populate();
@@ -923,6 +971,7 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,
 			shutdown_mem_profiling(true);
 			pr_err("Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\n",
 			       mod->name);
+			release_module_tags(mod, false);
 			return ERR_PTR(grow_res);
 		}
 	}
@@ -930,52 +979,6 @@ static void *reserve_module_tags(struct module *mod, unsigned long size,
 	return (struct alloc_tag *)(module_tags.start_addr + offset);
 }
 
-static void release_module_tags(struct module *mod, bool used)
-{
-	MA_STATE(mas, &mod_area_mt, module_tags.size, module_tags.size);
-	struct alloc_tag *start_tag;
-	struct alloc_tag *end_tag;
-	struct module *val;
-
-	mas_lock(&mas);
-	mas_for_each_rev(&mas, val, 0)
-		if (val == mod)
-			break;
-
-	if (!val) /* module not found */
-		goto out;
-
-	if (!used)
-		goto release_area;
-
-	start_tag = (struct alloc_tag *)(module_tags.start_addr + mas.index);
-	end_tag = (struct alloc_tag *)(module_tags.start_addr + mas.last);
-	if (!clean_unused_counters(start_tag, end_tag)) {
-		struct alloc_tag *tag;
-
-		for (tag = start_tag; tag <= end_tag; tag++) {
-			struct alloc_tag_counters counter;
-
-			if (!tag->counters)
-				continue;
-
-			counter = alloc_tag_read(tag);
-			pr_info("%s:%u module %s func:%s has %llu allocated at module unload\n",
-				tag->ct.filename, tag->ct.lineno, tag->ct.modname,
-				tag->ct.function, counter.bytes);
-		}
-	} else {
-		used = false;
-	}
-release_area:
-	mas_store(&mas, used ? &unloaded_mod : NULL);
-	val = mas_prev_range(&mas, 0);
-	if (val == &prepend_mod)
-		mas_store(&mas, NULL);
-out:
-	mas_unlock(&mas);
-}
-
 static int load_module(struct module *mod, struct codetag *start, struct codetag *stop)
 {
 	/* Allocate module alloc_tag percpu counters */

31/3 2026/09/03 00:30 llm kmsan-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 6678
							output: 20
							thoughts: 846

Thoughts: 
**Analyzing the Patch for Uninitialized Memory Risks**

Okay, let's dive into this patch. My initial thought is to assess if it introduces any uninitialized memory risks, which would necessitate a dedicated KMSAN fuzzing session. I'll start by reading the patch diff itself. It's touching module loading, specifically `include/linux/module.h`, `kernel/module/internal.h`, `kernel/module/main.c`, and `mm/alloc_tag.c`. This suggests changes to how modules are loaded, relocated, and potentially memory is managed.

First, the enum change. Adding `MOD_STANDALONE = -2` to `enum mod_mem_type` in `include/linux/module.h` is straightforward. Then `SH_ENTSIZE_STANDALONE` in `kernel/module/internal.h` seems to be a derived value based on that enum. It looks like `SH_ENTSIZE_STANDALONE` is related to codetag sections. I will keep that in mind.

Now for the meat of it in `kernel/module/main.c`. Interesting. The patch is removing exceptions and handling related to `infosec` within `apply_relocations()`. Also, code to remove codetag handling from both `__layout_sections()` and `move_module()`. The patch also moves resetting `info->sechdrs[i].sh_entsize = ~0UL;` from `layout_sections()` to `layout_and_allocate()`. The new function `allocate_codetag_sections()` is very interesting. It iterates through sections, conditionally calls `codetag_alloc_module_section()`, and copies data, setting `shdr->sh_addr` and `shdr->sh_entsize` to `SH_ENTSIZE_STANDALONE`. I need to inspect this function carefully with respect to allocation and copy semantics; specifically the data copying into the dest variable. Finally, I see that the `layout_and_allocate()` function now initializes `sh_entsize` to `~0UL` and also sets `info->sechdrs[info->index.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;` for non-zero `pcpu` indices before calling other layout functions.

Finally, in `mm/alloc_tag.c`, the reordering of `release_module_tags()` and `reserve_module_tags()` looks important. The logic in `reserve_module_tags()` around `tags_addressable()` and the subsequent calls to `shutdown_mem_profiling()`, `release_module_tags()`, and `vm_module_tags_populate()` is what I need to watch. Any failure scenarios here could expose uninitialized memory.

My next step is to deeply examine the usage of `info->sechdrs` and how memory is allocated and managed, especially around `layout_and_allocate()`, `allocate_codetag_sections()` and the codetag related code. I'll need to use `grepper` or equivalent tools to search for these functions and their related data structures to get a full picture. I will be looking for patterns that can lead to memory leakage, use of uninitialized memory or anything suspicious. This is where the devil is going to be.

32/3 2026/09/03 00:30 tool grepper
0m Args: 
{
  "Expression": "allocate_codetag_sections"
}

Results: 
{
  "Output": "kernel/module/main.c=2902=core_param(module_blacklist, module_blacklist, charp, 0400);\n--\nkernel/module/main.c-2911- */\nkernel/module/main.c:2912:static int allocate_codetag_sections(struct load_info *info)\nkernel/module/main.c-2913-{\n--\nkernel/module/main.c=2945=static struct module *layout_and_allocate(struct load_info *info, int flags)\n--\nkernel/module/main.c-2977-\t/* Allow codetag sections to be allocated separately first. */\nkernel/module/main.c:2978:\terr = allocate_codetag_sections(info);\nkernel/module/main.c-2979-\tif (err)\n"
}
33/3 2026/09/03 00:30 llm kmsan-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 8468
							output: 36
							thoughts: 27

Thoughts: 
Here's a summary of my thought process:

**Diving into Module Relocation**

Okay, I need to understand what's happening with module layout and allocation, and how modules are moved around in memory. My immediate instinct is to look directly at the code where the core logic of module manipulation resides. Let's start with `kernel/module/main.c`. Specifically, I'm going to focus my attention around the `layout_and_allocate` and `move_module` functions. Those functions are likely where the heavy lifting of module relocation and memory management is done. I'll need to see how the system decides where to put the module, and precisely how it handles the data transfer when it needs to be repositioned.

34/3 2026/09/03 00:30 tool read-file
0m Args: 
{
  "File": "kernel/module/main.c",
  "FirstLine": 2945,
  "LineCount": 80
}

Results: 
{
  "Contents": "2945:\tstatic struct module *layout_and_allocate(struct load_info *info, int flags)\n2946:\t{\n2947:\t\tstruct module *mod;\n2948:\t\tunsigned int i;\n2949:\t\tint err;\n2950:\t\n2951:\t\t/* Allow arches to frob section contents and sizes.  */\n2952:\t\terr = module_frob_arch_sections(info-\u003ehdr, info-\u003esechdrs,\n2953:\t\t\t\t\t\tinfo-\u003esecstrings, info-\u003emod);\n2954:\t\tif (err \u003c 0)\n2955:\t\t\treturn ERR_PTR(err);\n2956:\t\n2957:\t\terr = module_enforce_rwx_sections(info-\u003ehdr, info-\u003esechdrs,\n2958:\t\t\t\t\t\t  info-\u003esecstrings, info-\u003emod);\n2959:\t\tif (err \u003c 0)\n2960:\t\t\treturn ERR_PTR(err);\n2961:\t\n2962:\t\t/* Repurpose sh_entsize to track where each section is allocated. */\n2963:\t\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n2964:\t\t\tinfo-\u003esechdrs[i].sh_entsize = ~0UL;\n2965:\t\n2966:\t\t/* We will do a special allocation for per-cpu sections later. */\n2967:\t\tif (info-\u003eindex.pcpu)\n2968:\t\t\tinfo-\u003esechdrs[info-\u003eindex.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;\n2969:\t\n2970:\t\t/*\n2971:\t\t * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can\n2972:\t\t * put them in the right place.\n2973:\t\t * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set.\n2974:\t\t */\n2975:\t\tmodule_mark_ro_after_init(info-\u003ehdr, info-\u003esechdrs, info-\u003esecstrings);\n2976:\t\n2977:\t\t/* Allow codetag sections to be allocated separately first. */\n2978:\t\terr = allocate_codetag_sections(info);\n2979:\t\tif (err)\n2980:\t\t\treturn ERR_PTR(err);\n2981:\t\n2982:\t\t/* Determine total sizes and put offsets in sh_entsize. */\n2983:\t\tlayout_sections(info-\u003emod, info);\n2984:\t\tlayout_symtab(info-\u003emod, info);\n2985:\t\n2986:\t\t/* Allocate and move to the final place */\n2987:\t\terr = move_module(info-\u003emod, info);\n2988:\t\tif (err) {\n2989:\t\t\tcodetag_free_module_sections(info-\u003emod);\n2990:\t\t\treturn ERR_PTR(err);\n2991:\t\t}\n2992:\t\n2993:\t\t/* Module has been copied to its final place now: return it. */\n2994:\t\tmod = (void *)info-\u003esechdrs[info-\u003eindex.mod].sh_addr;\n2995:\t\tkmemleak_load_module(mod, info);\n2996:\t\tcodetag_module_replaced(info-\u003emod, mod);\n2997:\t\n2998:\t\treturn mod;\n2999:\t}\n3000:\t\n3001:\t/* mod is no longer valid after this! */\n3002:\tstatic void module_deallocate(struct module *mod, struct load_info *info)\n3003:\t{\n3004:\t\tpercpu_modfree(mod);\n3005:\t\tmodule_arch_freeing_init(mod);\n3006:\t\tcodetag_free_module_sections(mod);\n3007:\t\n3008:\t\tfree_mod_mem(mod);\n3009:\t}\n3010:\t\n3011:\tint __weak module_finalize(const Elf_Ehdr *hdr,\n3012:\t\t\t\t   const Elf_Shdr *sechdrs,\n3013:\t\t\t\t   struct module *me)\n3014:\t{\n3015:\t\treturn 0;\n3016:\t}\n3017:\t\n3018:\tstatic int post_relocation(struct module *mod, const struct load_info *info)\n3019:\t{\n3020:\t\t/* Sort exception table now relocations are done. */\n3021:\t\tsort_extable(mod-\u003eextable, mod-\u003eextable + mod-\u003enum_exentries);\n3022:\t\n3023:\t\t/* Copy relocated percpu area over. */\n3024:\t\tpercpu_modcopy(mod, (void *)info-\u003esechdrs[info-\u003eindex.pcpu].sh_addr,\n"
}
35/3 2026/09/03 00:30 llm kmsan-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 9958
							output: 27
							thoughts: 447

Thoughts: 
**Analyzing Code Tag Section Allocation**

Okay, let's dive into this `allocate_codetag_sections` function. It looks like we're iterating through section headers, starting from the second one (index 1). The goal seems to be allocating memory for sections that meet a specific "codetag" criteria within a module. The function is going through the section headers and it looks like `codetag_needs_module_section` decides which sections should be moved or managed differently.

The `codetag_alloc_module_section` call is interesting. It seems to handle the actual memory allocation, potentially prepending something based on the architecture, handling alignment and the section's size. There's error handling to manage allocation failure using `WARN_ON`, and some fallback logic involving `-EAGAIN` to treat it like a regular section, and general error handling, freeing allocations on failure.

Finally, if allocation is successful and the section is *not* a no-bits section, we copy the data from the original section address (`shdr->sh_addr`) to the newly allocated destination. The `shdr->sh_addr` is then updated to point to the new location, and the section size is set.

Now, a key question is how `shdr->sh_addr` is *initially* set. I need to understand where that value comes from before we reach this function. Specifically, before the allocation happens in `layout_and_allocate`. I need to figure out where the section addresses are initially set within the module loading process. I'll search for uses of the `setup_load_info` function or the `load_info` structure itself. Understanding how `shdr->sh_addr` gets its initial value is crucial to understanding the whole process.

36/3 2026/09/03 00:30 tool grepper
0m Args: 
{
  "Expression": "sh_addr",
  "PathPrefix": "kernel/module/"
}

Results: 
{
  "Output": "kernel/module/kallsyms.c=113=void layout_symtab(struct module *mod, struct load_info *info)\n--\nkernel/module/kallsyms.c-141-\t/* Append room for core symbols at end of core part. */\nkernel/module/kallsyms.c:142:\tinfo-\u003esymoffs = ALIGN(mod_mem_data-\u003esize, symsect-\u003esh_addralign ?: 1);\nkernel/module/kallsyms.c-143-\tinfo-\u003estroffs = mod_mem_data-\u003esize = info-\u003esymoffs + ndst * sizeof(Elf_Sym);\n--\nkernel/module/kallsyms.c=170=void add_kallsyms(struct module *mod, const struct load_info *info)\n--\nkernel/module/kallsyms.c-183-\nkernel/module/kallsyms.c:184:\tkallsyms-\u003esymtab = (void *)symsec-\u003esh_addr;\nkernel/module/kallsyms.c-185-\tkallsyms-\u003enum_symtab = symsec-\u003esh_size / sizeof(Elf_Sym);\nkernel/module/kallsyms.c-186-\t/* Make sure we get permanent strtab: don't use info-\u003estrtab. */\nkernel/module/kallsyms.c:187:\tkallsyms-\u003estrtab = (void *)info-\u003esechdrs[info-\u003eindex.str].sh_addr;\nkernel/module/kallsyms.c-188-\tkallsyms-\u003etypetab = init_data_base + info-\u003einit_typeoffs;\n--\nkernel/module/kallsyms.c=225=void init_build_id(struct module *mod, const struct load_info *info)\n--\nkernel/module/kallsyms.c-232-\t\tif (!sect_empty(sechdr) \u0026\u0026 sechdr-\u003esh_type == SHT_NOTE \u0026\u0026\nkernel/module/kallsyms.c:233:\t\t    !build_id_parse_buf((void *)sechdr-\u003esh_addr, mod-\u003ebuild_id,\nkernel/module/kallsyms.c-234-\t\t\t\t\tsechdr-\u003esh_size))\n--\nkernel/module/livepatch.c=18=int copy_module_elf(struct module *mod, struct load_info *info)\n--\nkernel/module/livepatch.c-53-\t * For livepatch modules, core_kallsyms.symtab is a complete\nkernel/module/livepatch.c:54:\t * copy of the original symbol table. Adjust sh_addr to point\nkernel/module/livepatch.c-55-\t * to core_kallsyms.symtab since the copy of the symtab in module\n--\nkernel/module/livepatch.c-57-\t */\nkernel/module/livepatch.c:58:\tmod-\u003eklp_info-\u003esechdrs[symndx].sh_addr = (unsigned long)mod-\u003ecore_kallsyms.symtab;\nkernel/module/livepatch.c-59-\n--\nkernel/module/main.c=284=static void *section_addr(const struct load_info *info, const char *name)\nkernel/module/main.c-285-{\nkernel/module/main.c:286:\t/* Section 0 has sh_addr 0. */\nkernel/module/main.c:287:\treturn (void *)info-\u003esechdrs[find_sec(info, name)].sh_addr;\nkernel/module/main.c-288-}\n--\nkernel/module/main.c=291=static void *section_objs(const struct load_info *info,\n--\nkernel/module/main.c-297-\nkernel/module/main.c:298:\t/* Section 0 has sh_addr 0 and sh_size 0. */\nkernel/module/main.c-299-\t*num = info-\u003esechdrs[sec].sh_size / object_size;\nkernel/module/main.c:300:\treturn (void *)info-\u003esechdrs[sec].sh_addr;\nkernel/module/main.c-301-}\n--\nkernel/module/main.c=320=static __maybe_unused void *any_section_objs(const struct load_info *info,\n--\nkernel/module/main.c-326-\nkernel/module/main.c:327:\t/* Section 0 has sh_addr 0 and sh_size 0. */\nkernel/module/main.c-328-\t*num = info-\u003esechdrs[sec].sh_size / object_size;\nkernel/module/main.c:329:\treturn (void *)info-\u003esechdrs[sec].sh_addr;\nkernel/module/main.c-330-}\n--\nkernel/module/main.c=455=static int percpu_modalloc(struct module *mod, struct load_info *info)\n--\nkernel/module/main.c-457-\tElf_Shdr *pcpusec = \u0026info-\u003esechdrs[info-\u003eindex.pcpu];\nkernel/module/main.c:458:\tunsigned long align = pcpusec-\u003esh_addralign;\nkernel/module/main.c-459-\n--\nkernel/module/main.c=1138=static char *get_next_modinfo(const struct load_info *info, const char *tag,\n--\nkernel/module/main.c-1147-\t * get_modinfo() calls made before rewrite_section_headers()\nkernel/module/main.c:1148:\t * must use sh_offset, as sh_addr isn't set!\nkernel/module/main.c-1149-\t */\n--\nkernel/module/main.c=1529=static int simplify_symbols(struct module *mod, const struct load_info *info)\n--\nkernel/module/main.c-1531-\tElf_Shdr *symsec = \u0026info-\u003esechdrs[info-\u003eindex.sym];\nkernel/module/main.c:1532:\tElf_Sym *sym = (void *)symsec-\u003esh_addr;\nkernel/module/main.c-1533-\tunsigned long secbase;\n--\nkernel/module/main.c-1597-\t\t\telse\nkernel/module/main.c:1598:\t\t\t\tsecbase = info-\u003esechdrs[sym[i].st_shndx].sh_addr;\nkernel/module/main.c-1599-\t\t\tsym[i].st_value += secbase;\n--\nkernel/module/main.c=1650=long module_get_offset_and_type(struct module *mod, enum mod_mem_type type,\n--\nkernel/module/main.c-1656-\tmod-\u003emem[type].size += arch_mod_section_prepend(mod, section);\nkernel/module/main.c:1657:\toffset = ALIGN(mod-\u003emem[type].size, sechdr-\u003esh_addralign ?: 1);\nkernel/module/main.c-1658-\tmod-\u003emem[type].size = offset + sechdr-\u003esh_size;\n--\nkernel/module/main.c=1915=static int elf_validity_cache_sechdrs(struct load_info *info)\n--\nkernel/module/main.c-1950-\t    || sechdrs[0].sh_size != 0\nkernel/module/main.c:1951:\t    || sechdrs[0].sh_addr != 0) {\nkernel/module/main.c-1952-\t\tpr_err(\"ELF Spec violation: section 0 type(%d)!=SH_NULL or non-zero len or addr\\n\",\n--\nkernel/module/main.c=2516=static int rewrite_section_headers(struct load_info *info, int flags)\n--\nkernel/module/main.c-2520-\t/* This should always be true, but let's be sure. */\nkernel/module/main.c:2521:\tinfo-\u003esechdrs[0].sh_addr = 0;\nkernel/module/main.c-2522-\n--\nkernel/module/main.c-2526-\t\t/*\nkernel/module/main.c:2527:\t\t * Mark all sections sh_addr with their address in the\nkernel/module/main.c-2528-\t\t * temporary image.\nkernel/module/main.c-2529-\t\t */\nkernel/module/main.c:2530:\t\tshdr-\u003esh_addr = (size_t)info-\u003ehdr + shdr-\u003esh_offset;\nkernel/module/main.c-2531-\n--\nkernel/module/main.c=2773=static int move_module(struct module *mod, struct load_info *info)\n--\nkernel/module/main.c-2815-\t\t\t}\nkernel/module/main.c:2816:\t\t\tmemcpy(dest, (void *)shdr-\u003esh_addr, shdr-\u003esh_size);\nkernel/module/main.c-2817-\t\t}\n--\nkernel/module/main.c-2823-\t\t */\nkernel/module/main.c:2824:\t\tshdr-\u003esh_addr = (unsigned long)dest;\nkernel/module/main.c:2825:\t\tpr_debug(\"\\t0x%lx 0x%.8lx %s\\n\", (long)shdr-\u003esh_addr,\nkernel/module/main.c-2826-\t\t\t (long)shdr-\u003esh_size, info-\u003esecstrings + shdr-\u003esh_name);\n--\nkernel/module/main.c=2912=static int allocate_codetag_sections(struct load_info *info)\n--\nkernel/module/main.c-2922-\t\tdest = codetag_alloc_module_section(info-\u003emod, sname, shdr-\u003esh_size,\nkernel/module/main.c:2923:\t\t\t\tarch_mod_section_prepend(info-\u003emod, i), shdr-\u003esh_addralign);\nkernel/module/main.c-2924-\t\tif (WARN_ON(!dest)) {\n--\nkernel/module/main.c-2936-\t\tif (shdr-\u003esh_type != SHT_NOBITS)\nkernel/module/main.c:2937:\t\t\tmemcpy(dest, (void *)shdr-\u003esh_addr, shdr-\u003esh_size);\nkernel/module/main.c:2938:\t\tshdr-\u003esh_addr = (unsigned long)dest;\nkernel/module/main.c-2939-\t\tshdr-\u003esh_entsize = SH_ENTSIZE_STANDALONE;\n--\nkernel/module/main.c=2945=static struct module *layout_and_allocate(struct load_info *info, int flags)\n--\nkernel/module/main.c-2993-\t/* Module has been copied to its final place now: return it. */\nkernel/module/main.c:2994:\tmod = (void *)info-\u003esechdrs[info-\u003eindex.mod].sh_addr;\nkernel/module/main.c-2995-\tkmemleak_load_module(mod, info);\n--\nkernel/module/main.c=3018=static int post_relocation(struct module *mod, const struct load_info *info)\n--\nkernel/module/main.c-3023-\t/* Copy relocated percpu area over. */\nkernel/module/main.c:3024:\tpercpu_modcopy(mod, (void *)info-\u003esechdrs[info-\u003eindex.pcpu].sh_addr,\nkernel/module/main.c-3025-\t\t       info-\u003esechdrs[info-\u003eindex.pcpu].sh_size);\n--\nkernel/module/sysfs.c=65=static int add_sect_attrs(struct module *mod, const struct load_info *info)\n--\nkernel/module/sysfs.c-104-\t\tsattr-\u003eread = module_sect_read;\nkernel/module/sysfs.c:105:\t\tsattr-\u003eprivate = (void *)sec-\u003esh_addr;\nkernel/module/sysfs.c-106-\t\tsattr-\u003esize = MODULE_SECT_READ_SIZE;\n--\nkernel/module/sysfs.c=151=static int add_notes_attrs(struct module *mod, const struct load_info *info)\n--\nkernel/module/sysfs.c-190-\t\t\tnattr-\u003esize = info-\u003esechdrs[i].sh_size;\nkernel/module/sysfs.c:191:\t\t\tnattr-\u003eprivate = (void *)info-\u003esechdrs[i].sh_addr;\nkernel/module/sysfs.c-192-\t\t\tnattr-\u003eread = sysfs_bin_attr_simple_read;\n--\nkernel/module/version.c=13=int check_version(const struct load_info *info,\n--\nkernel/module/version.c-47-\nkernel/module/version.c:48:\tversions = (void *)sechdrs[versindex].sh_addr;\nkernel/module/version.c-49-\tnum_versions = sechdrs[versindex].sh_size\n--\nkernel/module/version.c=107=void modversion_ext_start(const struct load_info *info,\n--\nkernel/module/version.c-122-\nkernel/module/version.c:123:\tstart-\u003ecrc = (const u32 *)sechdrs[crc_idx].sh_addr;\nkernel/module/version.c:124:\tstart-\u003ename = (const char *)sechdrs[name_idx].sh_addr;\nkernel/module/version.c-125-\tstart-\u003eremaining = sechdrs[crc_idx].sh_size / sizeof(*start-\u003ecrc);\n"
}
37/3 2026/09/03 00:30 llm kmsan-evaluator
0m Model: 
gemini-3.7-flash

Args: 
null

Results: 
null

Tokens: 
							input: 14284
							output: 237
							thoughts: 1401

Thoughts: 
**Analysis of Module Loading and KMSAN Determination**

Okay, let's break this down. My initial assessment centers on how this patch modifies the module loading process, specifically regarding sections designated as "standalone," such as per-CPU sections and code tag sections. The core of the changes appears in `kernel/module/main.c` and relates to the ELF section layout and allocation. The intention is to handle these standalone sections separately, potentially allocating them into dedicated memory regions rather than placing them within the main module memory area. This involves an interesting dance with `sh_entsize` being set to `SH_ENTSIZE_STANDALONE` and then the subsequent steps based on that setting.

The process kicks off with `rewrite_section_headers` which, as expected, sets `sh_addr` based on the section's offset into the initial module image. Then, `layout_and_allocate` is called. Here's where it gets interesting: the logic in `allocate_codetag_sections` attempts to allocate codetag sections separately using `codetag_alloc_module_section`. If successful, the data is copied using `memcpy`. Crucially, if this allocation fails (returning `-EAGAIN`), the section is *not* marked as standalone, which means `layout_sections` will lay it out in the normal module memory. That's a crucial point to check. `layout_sections` subsequently skips standalone sections, meaning those are *not* handled by the general layout logic. After section layout is done, `move_module` is called, and, again, standalone sections are skipped. The sections that were laid out in the normal module memory are copied from the original ELF buffer.

My mind then shifts to `apply_relocations()`. The historical handling of the `pcpu` section is where the change is most evident. Before, the `pcpu` section was special, and its `SHF_ALLOC` flag was stripped, which is why it was handled in a different manner with relocations applied to the initial ELF template and then copied. This patch, however, maintains the `SHF_ALLOC` flag for the `pcpu` section, but it is treated like any other standalone section. The `sh_entsize` being set to `SH_ENTSIZE_STANDALONE` effectively flags it for separate handling and is then properly relocated.

The analysis of the `alloc_tag.c` changes is straightforward. They involve error handling in tag allocation, specifically around failures in `reserve_module_tags` and `vm_module_tags_populate`.

Now, the critical question: are there any uninitialized memory risks? Let's go through the checklist. After a detailed review, the initial ELF module image (`info->hdr + shdr->sh_offset`) is always valid memory. Section data is copied using `memcpy` from initialized ELF image memory, and no information leaks to user space are present. No conditional branching depends on uninitialized variables, and the structures are always properly initialized. In short, there are no uninitialized variables being read, written, or copied that could lead to vulnerabilities. Any memory errors that arise here (out-of-bounds reads/writes, memory leaks, etc.) would be caught by KASAN.

Given this thorough analysis, and based on the KMSAN criteria, there's no reason to flag this as needing KMSAN. This patch doesn't introduce any of the vulnerabilities that KMSAN is designed to catch, such as uninitialized kernel-to-user space data or branching on uninitialized variables. This really boils down to: this patch is refactoring module loading. It changes how standalone sections are handled during module loading. Memory is allocated from the original loaded ELF module image. Any potential bugs are standard memory issues, which will be caught by KASAN. Therefore, `NeedsKMSAN` is `false`.

38/3 2026/09/03 00:30 tool set-results
0m Args: 
{
  "KMSANReasoning": "The patch refactors the ELF section layout and allocation logic for standalone module sections (such as per-CPU sections and codetag/alloc_tag sections) during module loading in `kernel/module/main.c` and adjusts error handling in `mm/alloc_tag.c`.\n\nKMSAN vs KASAN analysis:\n- KMSAN detects reads of uninitialized memory and information leaks to user space. The patch does not introduce uninitialized stack or heap variables, does not leave structure paddings uninitialized, does not expose data to user space, and does not introduce branches on uninitialized state. The section data copied via `memcpy()` originates from already-loaded ELF image buffers.\n- Any potential memory management issues introduced by changes to section layouts, relocations, or separate memory allocations (such as out-of-bounds section reads/writes, buffer overflows, or use-after-free conditions) are addressable errors that are detected by standard KASAN.\n\nTherefore, dedicated KMSAN fuzzing is not required.",
  "NeedsKMSAN": false
}

Results: 
{
  "KMSANReasoning": "The patch refactors the ELF section layout and allocation logic for standalone module sections (such as per-CPU sections and codetag/alloc_tag sections) during module loading in `kernel/module/main.c` and adjusts error handling in `mm/alloc_tag.c`.\n\nKMSAN vs KASAN analysis:\n- KMSAN detects reads of uninitialized memory and information leaks to user space. The patch does not introduce uninitialized stack or heap variables, does not leave structure paddings uninitialized, does not expose data to user space, and does not introduce branches on uninitialized state. The section data copied via `memcpy()` originates from already-loaded ELF image buffers.\n- Any potential memory management issues introduced by changes to section layouts, relocations, or separate memory allocations (such as out-of-bounds section reads/writes, buffer overflows, or use-after-free conditions) are addressable errors that are detected by standard KASAN.\n\nTherefore, dedicated KMSAN fuzzing is not required.",
  "NeedsKMSAN": false
}
LLM Calls Summary:
Total Calls Total Tokens Avg Tokens Total Duration (Seconds) Avg Duration (Seconds)
Tool Calls Summary:
Total Calls Total Duration (Seconds) Avg Duration (Seconds)