AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/10/20 00:29	flow	finding-triage	2m Args: null Results: { "Introduced": false, "Reasoning": "The crash report details a lockdep warning regarding a possible circular locking dependency:\n`fs_reclaim --\u003e \u0026cpuctx_mutex --\u003e \u0026mm-\u003emmap_lock`.\n\nThe dependency chain involves:\n1. `perf_ioctl()` holding `perf_event_context` mutex (`\u0026cpuctx_mutex`) while invoking `perf_event_set_filter()`, which calls `strndup_user()`, establishing a dependency of `\u0026cpuctx_mutex --\u003e \u0026mm-\u003emmap_lock`.\n2. CPU hotplug and PMU registration paths linking `cpu_hotplug_lock`, `cpuhp_state-up`, `pmus_lock`, and `cpuctx_mutex`.\n3. Network Block Device (`nbd`) operations interacting with queue locks, elevator locks, and memory allocations.\n4. An `ip_mroute_setsockopt()` syscall page faulting during `copy_from_sockptr()`, prompting stack expansion via `expand_downwards()`, which allocates Maple Tree nodes under `\u0026mm-\u003emmap_lock` with `GFP_KERNEL` (`fs_reclaim`).\n\nThe tested patch series (\"bpf: Add syscall common attrs support for link_create\") only touches BPF link creation logging in `kernel/bpf/syscall.c`, `kernel/bpf/log.c`, `net/core/dev.c`, and user-space tooling/selftests. It does not touch perf, nbd, mmap_lock, page fault handling, or any of the locks involved in this lockdep warning. This is a pre-existing lock ordering issue triggered independently during fuzzing." }
1/1	2026/10/20 00:29	action	prepare-finding-overview	0m Args: null Results: { "DiffStat": "include/linux/bpf_verifier.h \| 6 ++\n include/linux/netdevice.h \| 3 +-\n include/trace/events/xdp.h \| 17 ----\n kernel/bpf/log.c \| 19 ++--\n kernel/bpf/syscall.c \| 41 +++++++--\n net/core/dev.c \| 8 +-\n tools/lib/bpf/bpf.c \| 69 ++++++++++----\n tools/lib/bpf/bpf.h \| 5 +\n tools/lib/bpf/libbpf.map \| 2 +\n .../testing/selftests/bpf/prog_tests/xdp_attach.c \| 65 -------------\n tools/testing/selftests/bpf/prog_tests/xdp_link.c \| 101 +++++++++++++++++++++\n .../selftests/bpf/progs/test_xdp_attach_fail.c \| 54 -----------\n 12 files changed, 217 insertions(+), 173 deletions(-)", "HasCover": false, "PatchCount": 6, "PatchList": "The patch series contains 6 patches:\n[1] [PATCH bpf-next v2 1/6] bpf: Add syscall common attrs support for link_create\n[2] [PATCH bpf-next v2 2/6] bpf: Add syscall common attrs support for xdp link_create\n[3] [PATCH bpf-next v2 3/6] bpf: Retire tracepoint bpf_xdp_link_attach_failed\n[4] [PATCH bpf-next v2 4/6] libbpf: Factor out __sys_bpf_fd helper\n[5] [PATCH bpf-next v2 5/6] libbpf: Add bpf_link_create_log API\n[6] [PATCH bpf-next v2 6/6] selftests/bpf: Add tests to verify link_create logs" }
2/1	2026/10/20 00:29	agent	finding-triage-evaluator	2m Model: core Args: null Results: { "Introduced": false, "Reasoning": "The crash report details a lockdep warning regarding a possible circular locking dependency:\n`fs_reclaim --\u003e \u0026cpuctx_mutex --\u003e \u0026mm-\u003emmap_lock`.\n\nThe dependency chain involves:\n1. `perf_ioctl()` holding `perf_event_context` mutex (`\u0026cpuctx_mutex`) while invoking `perf_event_set_filter()`, which calls `strndup_user()`, establishing a dependency of `\u0026cpuctx_mutex --\u003e \u0026mm-\u003emmap_lock`.\n2. CPU hotplug and PMU registration paths linking `cpu_hotplug_lock`, `cpuhp_state-up`, `pmus_lock`, and `cpuctx_mutex`.\n3. Network Block Device (`nbd`) operations interacting with queue locks, elevator locks, and memory allocations.\n4. An `ip_mroute_setsockopt()` syscall page faulting during `copy_from_sockptr()`, prompting stack expansion via `expand_downwards()`, which allocates Maple Tree nodes under `\u0026mm-\u003emmap_lock` with `GFP_KERNEL` (`fs_reclaim`).\n\nThe tested patch series (\"bpf: Add syscall common attrs support for link_create\") only touches BPF link creation logging in `kernel/bpf/syscall.c`, `kernel/bpf/log.c`, `net/core/dev.c`, and user-space tooling/selftests. It does not touch perf, nbd, mmap_lock, page fault handling, or any of the locks involved in this lockdep warning. This is a pre-existing lock ordering issue triggered independently during fuzzing." } Instruction: You are an expert Linux kernel maintainer and security engineer specializing in crash triage and root-cause analysis. Your job is to review a kernel crash report (finding) and determine if it was introduced / caused by the patch series being tested, or if it is a pre-existing / unrelated bug. IMPORTANT: The entire patch series has ALREADY been applied and committed as a single squashed commit at HEAD (or on top of the base commit) in your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively use your tools to examine the source code, inspect workspace diffs, and confirm any assumptions. Available Tools: - git-show: View the squashed patch series commit or historical commits. Call with Commit="HEAD" (default) and optional 'File' parameter to restrict the diff to a specific file or directory, or 'Stat=true' for a diffstat. - series-patches: Browse the original patch series. Call without arguments to list all patch titles, or PatchNum=<N> to view the full description and diff of a specific patch (or cover letter, if present). - read-file & codesearch-dir-index: Read exact source code files and directory contents in the workspace. - grepper: Regex search across files in the workspace (git grep). - git-blame: Inspect line authorship and find which commit last modified specific lines of code. Triage Procedure: 1. Analyze the Crash Report: - Identify the crash type (e.g. NULL dereference, KASAN use-after-free, out-of-bounds read/write, assertion failure, deadlock). - Carefully examine the stack trace(s) — both the faulting call stack and, if applicable (e.g., KASAN UAF), the allocation and free stacks. - Note the faulting function, file name, line numbers, and the specific variables or data structures involved. 2. Inspect Workspace Changes & Patch Series: - Check if any files or functions from the stack trace appear in the modified files overview or the patch series. - Use git-show with Commit="HEAD" and 'File' to inspect the exact diffs for relevant files in the squashed commit. - If needed, use series-patches with PatchNum=<N> to inspect the author's commit description and rationale for individual patches in the series. - Use read-file to inspect the actual source code at the faulting lines. 3. Determine Causality: - Set Introduced=true ONLY IF you are absolutely certain: * There is clear, unambiguous, and conclusive evidence that the crash was directly introduced or caused by the patch series. * The crash occurs directly in new or modified code introduced by the patch series, or the patch series altered data structures, locking, object lifetimes, or preconditions in a way that directly triggered the failure in existing code. - Set Introduced=false IF: * There is any doubt, ambiguity, or lack of conclusive proof that the patch series caused the bug. * The crash occurs in an unrelated subsystem or unmodified code path whose behavior is independent of the patch series. * The crash is a pre-existing kernel issue that was randomly triggered during fuzzing. 4. Formulate Output: - Set Introduced to true or false. - In Reasoning, provide a clear, step-by-step technical explanation detailing the crash type, the key stack frames, whether the affected code/structures were modified by the patch series, and the causal justification for your verdict. Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 The kernel crash report to triage is: ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.3961/20323 is trying to acquire lock: ffffffff8fe95920 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc_noprof+0x5f/0x600 but task is already holding lock: ffff8881b0814080 (&mm->mmap_lock){++++}-{4:4}, at: upgrade_mmap_lock_carefully+0xba/0x1b0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #10 (&mm->mmap_lock){++++}-{4:4}: __might_fault+0xcb/0x130 _copy_from_user+0x28/0xb0 memdup_user+0x5e/0xd0 strndup_user+0x68/0xd0 perf_ioctl+0x7ba/0x20d0 __se_sys_ioctl+0xfc/0x170 do_syscall_64+0x166/0x520 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #9 (&cpuctx_mutex){+.+.}-{4:4}: __mutex_lock+0x19d/0x1550 perf_event_init_cpu+0x66b/0x7a0 perf_event_init+0x16c/0x220 start_kernel+0x20b/0x3e0 x86_64_start_reservations+0x24/0x30 x86_64_start_kernel+0x137/0x1b0 common_startup_64+0x13e/0x157 -> #8 (pmus_lock){+.+.}-{4:4}: __mutex_lock+0x19d/0x1550 perf_event_init_cpu+0x1d1/0x7a0 cpuhp_invoke_callback+0x434/0x810 cpuhp_thread_fun+0x362/0x780 smpboot_thread_fn+0x565/0xa70 kthread+0x38b/0x480 ret_from_fork+0x514/0xb70 ret_from_fork_asm+0x1a/0x30 -> #7 (cpuhp_state-up){+.+.}-{0:0}: cpuhp_thread_fun+0x127/0x780 smpboot_thread_fn+0x565/0xa70 kthread+0x38b/0x480 ret_from_fork+0x514/0xb70 ret_from_fork_asm+0x1a/0x30 -> #6 (cpu_hotplug_lock){++++}-{0:0}: cpus_read_lock+0x42/0x160 static_key_slow_inc+0x12/0x30 nbd_genl_reconnect_sock_cb+0x69a/0xbb0 nbd_genl_foreach_sock+0x265/0x450 nbd_genl_reconfigure+0xbbb/0x1040 genl_family_rcv_msg_doit+0x233/0x340 genl_rcv_msg+0x614/0x7a0 netlink_rcv_skb+0x226/0x4a0 genl_rcv+0x28/0x40 netlink_unicast+0x7bd/0x940 netlink_sendmsg+0x813/0xb40 sock_sendmsg_nosec+0x13a/0x180 ____sys_sendmsg+0x54e/0x850 ___sys_sendmsg+0x2a5/0x360 __x64_sys_sendmsg+0x1b1/0x290 do_syscall_64+0x166/0x520 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #5 (&nsock->tx_lock){+.+.}-{4:4}: __mutex_lock+0x19d/0x1550 nbd_queue_rq+0x373/0xff0 blk_mq_dispatch_rq_list+0x499/0x1990 __blk_mq_sched_dispatch_requests+0xd36/0x1580 blk_mq_sched_dispatch_requests+0xd7/0x190 blk_mq_run_work_fn+0x16c/0x300 process_scheduled_works+0xc3d/0x1630 worker_thread+0xa47/0xfb0 kthread+0x38b/0x480 ret_from_fork+0x514/0xb70 ret_from_fork_asm+0x1a/0x30 -> #4 (&cmd->lock){+.+.}-{4:4}: __mutex_lock+0x19d/0x1550 nbd_queue_rq+0xc1/0xff0 blk_mq_dispatch_rq_list+0x499/0x1990 __blk_mq_sched_dispatch_requests+0xd36/0x1580 blk_mq_sched_dispatch_requests+0xd7/0x190 blk_mq_run_work_fn+0x16c/0x300 process_scheduled_works+0xc3d/0x1630 worker_thread+0xa47/0xfb0 kthread+0x38b/0x480 ret_from_fork+0x514/0xb70 ret_from_fork_asm+0x1a/0x30 -> #3 (set->srcu){.+.+}-{0:0}: __synchronize_srcu+0xc9/0x2f0 elevator_switch+0x1e8/0x7b0 elevator_change+0x2fa/0x480 elevator_set_default+0x375/0x440 blk_register_queue+0x3f3/0x4e0 __add_disk+0x6b8/0xdb0 add_disk_fwnode+0x100/0x3a0 nbd_dev_add+0x733/0xb60 nbd_init+0x168/0x1f0 do_one_initcall+0x250/0x870 do_initcall_level+0x10a/0x1a0 do_initcalls+0x59/0xa0 kernel_init_freeable+0x29d/0x3e0 kernel_init+0x22/0x1d0 ret_from_fork+0x514/0xb70 ret_from_fork_asm+0x1a/0x30 -> #2 (&q->elevator_lock){+.+.}-{4:4}: __mutex_lock+0x19d/0x1550 elevator_change+0x1af/0x480 elevator_set_none+0xb5/0x140 blk_mq_update_nr_hw_queues+0x5ef/0x19f0 nbd_start_device+0x189/0xb30 nbd_genl_connect+0x167d/0x1cd0 genl_family_rcv_msg_doit+0x233/0x340 genl_rcv_msg+0x614/0x7a0 netlink_rcv_skb+0x226/0x4a0 genl_rcv+0x28/0x40 netlink_unicast+0x7bd/0x940 netlink_sendmsg+0x813/0xb40 sock_sendmsg_nosec+0x13a/0x180 ____sys_sendmsg+0x54e/0x850 ___sys_sendmsg+0x2a5/0x360 __x64_sys_sendmsg+0x1b1/0x290 do_syscall_64+0x166/0x520 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#49){++++}-{0:0}: blk_alloc_queue+0x544/0x690 __blk_mq_alloc_disk+0x194/0x390 nbd_dev_add+0x494/0xb60 nbd_init+0x168/0x1f0 do_one_initcall+0x250/0x870 do_initcall_level+0x10a/0x1a0 do_initcalls+0x59/0xa0 kernel_init_freeable+0x29d/0x3e0 kernel_init+0x22/0x1d0 ret_from_fork+0x514/0xb70 ret_from_fork_asm+0x1a/0x30 -> #0 (fs_reclaim){+.+.}-{0:0}: __lock_acquire+0x164c/0x2de0 lock_acquire+0x115/0x350 fs_reclaim_acquire+0x71/0x100 kmem_cache_alloc_noprof+0x5f/0x600 mas_alloc_nodes+0x291/0x350 mas_preallocate+0x42a/0x840 expand_downwards+0x42d/0xc40 lock_mm_and_find_vma+0x1da/0x340 do_user_addr_fault+0x343/0x1340 exc_page_fault+0x6a/0xc0 asm_exc_page_fault+0x26/0x30 rep_movs_alternative+0x30/0xa0 _copy_from_user+0x7a/0xb0 copy_from_sockptr+0x48/0x70 ip_mroute_setsockopt+0x76b/0x10d0 do_ip_setsockopt+0xeba/0x2e30 ip_setsockopt+0x66/0x110 do_sock_setsockopt+0x17c/0x1b0 __x64_sys_setsockopt+0x13d/0x1b0 do_syscall_64+0x166/0x520 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: fs_reclaim --> &cpuctx_mutex --> &mm->mmap_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_lock); lock(&cpuctx_mutex); lock(&mm->mmap_lock); lock(fs_reclaim); * DEADLOCK * locks held by syz.0.3961/20323: 2, last CPU#0: #0: ffffffff9125ad80 (rtnl_mutex){+.+.}-{4:4}, at: ip_mroute_setsockopt+0x137/0x10d0 #1: ffff8881b0814080 (&mm->mmap_lock){++++}-{4:4}, at: upgrade_mmap_lock_carefully+0xba/0x1b0 stack backtrace: CPU: 0 UID: 0 PID: 20323 Comm: syz.0.3961 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0xe8/0x150 print_circular_bug+0x2e2/0x300 check_noncircular+0x12f/0x150 __lock_acquire+0x164c/0x2de0 lock_acquire+0x115/0x350 fs_reclaim_acquire+0x71/0x100 kmem_cache_alloc_noprof+0x5f/0x600 mas_alloc_nodes+0x291/0x350 mas_preallocate+0x42a/0x840 expand_downwards+0x42d/0xc40 lock_mm_and_find_vma+0x1da/0x340 do_user_addr_fault+0x343/0x1340 exc_page_fault+0x6a/0xc0 asm_exc_page_fault+0x26/0x30 RIP: 0010:rep_movs_alternative+0x30/0xa0 Code: 83 f9 08 73 25 85 c9 74 0f 8a 06 88 07 48 ff c7 48 ff c6 48 ff c9 75 f1 e9 bd 67 04 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 <48> 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 db 83 f9 08 RSP: 0018:ffffc900047d7ab0 EFLAGS: 00010212 RAX: 00007ffffffff001 RBX: 0000000000000010 RCX: 0000000000000010 RDX: 0000000000000001 RSI: 0000200000000000 RDI: ffffc900047d7b90 RBP: 0000000000000000 R08: ffffc900047d7b9f R09: 1ffff920008faf73 R10: dffffc0000000000 R11: fffff520008faf74 R12: f8f8f8f8f8f8f2f2 R13: dffffc0000000000 R14: ffffc900047d7b90 R15: 0000200000000000 _copy_from_user+0x7a/0xb0 copy_from_sockptr+0x48/0x70 ip_mroute_setsockopt+0x76b/0x10d0 do_ip_setsockopt+0xeba/0x2e30 ip_setsockopt+0x66/0x110 do_sock_setsockopt+0x17c/0x1b0 __x64_sys_setsockopt+0x13d/0x1b0 do_syscall_64+0x166/0x520 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f39aa39e559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f39a85f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f39aa625fa0 RCX: 00007f39aa39e559 RDX: 00000000000000cb RSI: 0000000000000000 RDI: 0000000000000005 RBP: 00007f39aa4358b0 R08: 0000000000000010 R09: 0000000000000000 R10: 0000200000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f39aa626038 R14: 00007f39aa625fa0 R15: 00007ffd05a74398 </TASK> Overview of modified files in the workspace: include/linux/bpf_verifier.h \| 6 ++ include/linux/netdevice.h \| 3 +- include/trace/events/xdp.h \| 17 ---- kernel/bpf/log.c \| 19 ++-- kernel/bpf/syscall.c \| 41 +++++++-- net/core/dev.c \| 8 +- tools/lib/bpf/bpf.c \| 69 ++++++++++---- tools/lib/bpf/bpf.h \| 5 + tools/lib/bpf/libbpf.map \| 2 + .../testing/selftests/bpf/prog_tests/xdp_attach.c \| 65 ------------- tools/testing/selftests/bpf/prog_tests/xdp_link.c \| 101 +++++++++++++++++++++ .../selftests/bpf/progs/test_xdp_attach_fail.c \| 54 ----------- 12 files changed, 217 insertions(+), 173 deletions(-) The patch series contains 6 patches: [1] [PATCH bpf-next v2 1/6] bpf: Add syscall common attrs support for link_create [2] [PATCH bpf-next v2 2/6] bpf: Add syscall common attrs support for xdp link_create [3] [PATCH bpf-next v2 3/6] bpf: Retire tracepoint bpf_xdp_link_attach_failed [4] [PATCH bpf-next v2 4/6] libbpf: Factor out __sys_bpf_fd helper [5] [PATCH bpf-next v2 5/6] libbpf: Add bpf_link_create_log API [6] [PATCH bpf-next v2 6/6] selftests/bpf: Add tests to verify link_create logs
3/2	2026/10/20 00:29	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 7782 output: 14 thoughts: 108 Thoughts: Okay, let's dive into this kernel crash report. Triage Time: A Possible Circular Locking Dependency Right, so I'm looking at this crash report, and my spidey-sense is tingling. That "WARNING: possible circular locking dependency detected" line immediately jumps out. Specifically, this `syz.0.3961/20323` process is the culprit, trying to grab `ffffffff8fe95920 (fs_reclaim)` while already holding `ffff8881b0814080 (&mm->mmap_lock)`. Classic circular dependency. We need to figure out how this is happening. My first instinct is to see if this has been addressed. Before I go too deep, let's see if there's an existing patch series addressing this or a similar issue. I'll reach for either `series-patches` or `git-show` to start looking for related fixes. Quickly scan for any recent activity around memory management, filesystem operations, and locking primitives. Let's see if we can get lucky.
4/2	2026/10/20 00:29	tool	git-show	0m Args: { "Stat": true } Results: { "Output": "commit 99b514553dc8da077177e79ff98885923607d8fd\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Oct 20 00:29:42 2026 +0000\n\n syz-cluster: applied patch under review\n\n include/linux/bpf_verifier.h \| 6 ++\n include/linux/netdevice.h \| 3 +-\n include/trace/events/xdp.h \| 17 ----\n kernel/bpf/log.c \| 19 ++--\n kernel/bpf/syscall.c \| 41 +++++++--\n net/core/dev.c \| 8 +-\n tools/lib/bpf/bpf.c \| 69 ++++++++++----\n tools/lib/bpf/bpf.h \| 5 +\n tools/lib/bpf/libbpf.map \| 2 +\n .../testing/selftests/bpf/prog_tests/xdp_attach.c \| 65 -------------\n tools/testing/selftests/bpf/prog_tests/xdp_link.c \| 101 +++++++++++++++++++++\n .../selftests/bpf/progs/test_xdp_attach_fail.c \| 54 -----------\n 12 files changed, 217 insertions(+), 173 deletions(-)\n" }
5/2	2026/10/20 00:29	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 8507 output: 26 thoughts: 15 Thoughts: Okay, let's dive into this code. Here's how I'm thinking about breaking down this patching process: Diving Deep into the Patch with `git show` Alright, I need to understand precisely what these patches are modifying. I know `git show` is the go-to tool for this, so that's where I'll begin. It allows me to see the individual changes each commit introduces, which is critical for making informed decisions. By inspecting the output of `git show`, I can dissect the changes file by file, line by line, and identify exactly how the patches alter the existing codebase. This granular view is essential for assessing impact, potential conflicts, and, ultimately, the suitability of the patch for integration. I'll be looking for changes in function signatures, data structures, and any core logic that could lead to unexpected behavior. This careful analysis is my first step in understanding the true nature of the patch.
6/2	2026/10/20 00:29	tool	git-show	0m Args: { "Commit": "HEAD", "File": "kernel/bpf/" } Results: { "Output": "commit 99b514553dc8da077177e79ff98885923607d8fd\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Oct 20 00:29:42 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/kernel/bpf/log.c b/kernel/bpf/log.c\nindex 5432c0fc442b2..2bcd62d9ad88b 100644\n--- a/kernel/bpf/log.c\n+++ b/kernel/bpf/log.c\n@@ -884,17 +884,22 @@ struct bpf_verifier_log bpf_log_attr_create_vlog(struct bpf_log_attr attr_log,\n \treturn log;\n }\n \n+int bpf_log_attr_report_size(struct bpf_log_attr attr, u32 size)\n+{\n+\tif (attr-\u003eoffsetof_true_size \u0026\u0026\n+\t copy_to_bpfptr_offset(attr-\u003euattr, attr-\u003eoffsetof_true_size, \u0026size, sizeof(size)))\n+\t\treturn -EFAULT;\n+\n+\treturn 0;\n+}\n+\n int bpf_log_attr_finalize(struct bpf_log_attr attr, struct bpf_verifier_log log)\n {\n \tu32 log_true_size;\n-\tint err;\n+\tint err, ret;\n \n \terr = bpf_vlog_finalize(log, \u0026log_true_size);\n \n-\tif (attr-\u003eoffsetof_true_size \u0026\u0026\n-\t copy_to_bpfptr_offset(attr-\u003euattr, attr-\u003eoffsetof_true_size, \u0026log_true_size,\n-\t\t\t\t sizeof(log_true_size)))\n-\t\treturn -EFAULT;\n-\n-\treturn err;\n+\tret = bpf_log_attr_report_size(attr, log_true_size);\n+\treturn ret ? ret : err;\n }\ndiff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c\nindex 849bc9136299d..5652ecf212896 100644\n--- a/kernel/bpf/syscall.c\n+++ b/kernel/bpf/syscall.c\n@@ -5856,8 +5856,11 @@ static int bpf_map_do_batch(const union bpf_attr attr,\n }\n \n #define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.path_fd\n-static int link_create(union bpf_attr attr, bpfptr_t uattr)\n+static int link_create(union bpf_attr attr, bpfptr_t uattr, struct bpf_common_attr attr_common,\n+\t\t bpfptr_t uattr_common, u32 size_common)\n {\n+\tstruct bpf_verifier_log log;\n+\tstruct bpf_log_attr attr_log;\n \tstruct bpf_prog prog;\n \tint ret;\n \n@@ -5867,14 +5870,28 @@ static int link_create(union bpf_attr attr, bpfptr_t uattr)\n \tif (attr-\u003elink_create.attach_type == BPF_STRUCT_OPS)\n \t\treturn bpf_struct_ops_link_create(attr);\n \n+\tlog = bpf_log_attr_create_vlog(\u0026attr_log, attr_common, uattr_common, size_common);\n+\tif (IS_ERR(log))\n+\t\treturn PTR_ERR(log);\n+\n \tprog = bpf_prog_get(attr-\u003elink_create.prog_fd);\n-\tif (IS_ERR(prog))\n-\t\treturn PTR_ERR(prog);\n+\tif (IS_ERR(prog)) {\n+\t\tbpf_log(log, \"Invalid prog_fd.\\n\");\n+\t\tret = PTR_ERR(prog);\n+\t\tprog = NULL;\n+\t\tgoto out;\n+\t}\n \n \tret = bpf_prog_attach_check_attach_type(prog,\n \t\t\t\t\t\tattr-\u003elink_create.attach_type);\n-\tif (ret)\n+\tif (ret) {\n+\t\tbpf_log(log, \"Invalid attach_type.\\n\");\n \t\tgoto out;\n+\t}\n+\n+\tret = bpf_log_attr_report_size(\u0026attr_log, 0);\n+\tif (ret)\n+\t\tgoto put_prog;\n \n \tswitch (prog-\u003etype) {\n \tcase BPF_PROG_TYPE_CGROUP_SKB:\n@@ -5925,7 +5942,7 @@ static int link_create(union bpf_attr attr, bpfptr_t uattr)\n \t\tbreak;\n #ifdef CONFIG_NET\n \tcase BPF_PROG_TYPE_XDP:\n-\t\tret = bpf_xdp_link_attach(attr, prog);\n+\t\tret = bpf_xdp_link_attach(attr, prog, log);\n \t\tbreak;\n \tcase BPF_PROG_TYPE_SCHED_CLS:\n \t\tif (attr-\u003elink_create.attach_type == BPF_TCX_INGRESS \|\|\n@@ -5953,12 +5970,22 @@ static int link_create(union bpf_attr attr, bpfptr_t uattr)\n \t\t\tret = bpf_uprobe_multi_link_attach(attr, prog);\n \t\tbreak;\n \tdefault:\n+\t\tbpf_log(log, \"Invalid prog type.\\n\");\n \t\tret = -EINVAL;\n \t}\n \n out:\n-\tif (ret \u003c 0)\n+\tif (ret \u003c 0) {\n+\t\tint err = bpf_log_attr_finalize(\u0026attr_log, log);\n+\n+\t\tret = err ? err : ret;\n+\t}\n+\n+put_prog:\n+\tif (ret \u003c 0 \u0026\u0026 prog)\n \t\tbpf_prog_put(prog);\n+\n+\tkfree(log);\n \treturn ret;\n }\n \n@@ -6530,7 +6557,7 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size,\n \t\terr = bpf_map_do_batch(\u0026attr, uattr.user, BPF_MAP_DELETE_BATCH);\n \t\tbreak;\n \tcase BPF_LINK_CREATE:\n-\t\terr = link_create(\u0026attr, uattr);\n+\t\terr = link_create(\u0026attr, uattr, \u0026attr_common, uattr_common, size_common);\n \t\tbreak;\n \tcase BPF_LINK_UPDATE:\n \t\terr = link_update(\u0026attr);\n" }
7/2	2026/10/20 00:29	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 10484 output: 28 thoughts: 28 Thoughts: Okay, here's my attempt at summarizing those thoughts, tailored for an expert audience and in the first person: Analyzing Network Device Driver Changes Alright, let's dive in. I need to get a handle on what's been tweaked in the network device driver space. Specifically, I'm going to start by pulling up the `git-show` output for changes touching `net/core/dev.c` and `include/linux/netdevice.h`. That's where the core device registration, unregistration, and fundamental data structures live, right? It'll give me a high-level view of any modifications to the core network device infrastructure. I expect to see changes related to new features, bug fixes, perhaps performance enhancements, or potentially even some refactoring of those crucial data structures. I'll be particularly interested in anything that suggests modifications to the device lifecycle or interface definitions. I'll be scrutinizing those header files for changes to structs like `net_device`, `netdev_ops`, and the like. This will hopefully show how the core layers interact with the changes, which is always an important area. Time to get to it!
8/2	2026/10/20 00:30	tool	git-show	0m Args: { "Commit": "HEAD", "File": "net/core/dev.c" } Results: { "Output": "commit 99b514553dc8da077177e79ff98885923607d8fd\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Oct 20 00:29:42 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/net/core/dev.c b/net/core/dev.c\nindex 18dc88990510a..a142613536b09 100644\n--- a/net/core/dev.c\n+++ b/net/core/dev.c\n@@ -97,6 +97,7 @@\n #include \u003clinux/kthread.h\u003e\n #include \u003clinux/bpf.h\u003e\n #include \u003clinux/bpf_trace.h\u003e\n+#include \u003clinux/bpf_verifier.h\u003e\n #include \u003cnet/net_namespace.h\u003e\n #include \u003cnet/sock.h\u003e\n #include \u003cnet/busy_poll.h\u003e\n@@ -10771,7 +10772,8 @@ static const struct bpf_link_ops bpf_xdp_link_lops = {\n \t.update_prog = bpf_xdp_link_update,\n };\n \n-int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog)\n+int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog,\n+\t\t\tstruct bpf_verifier_log log)\n {\n \tstruct net net = current-\u003ensproxy-\u003enet_ns;\n \tstruct bpf_link_primer link_primer;\n@@ -10784,6 +10786,7 @@ int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog)\n \tdev = dev_get_by_index(net, attr-\u003elink_create.target_ifindex);\n \tif (!dev) {\n \t\trtnl_unlock();\n+\t\tbpf_log(log, \"Invalid target_ifindex.\\n\");\n \t\treturn -EINVAL;\n \t}\n \n@@ -10812,7 +10815,8 @@ int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog)\n \tif (err) {\n \t\tlink-\u003edev = NULL;\n \t\tbpf_link_cleanup(\u0026link_primer);\n-\t\ttrace_bpf_xdp_link_attach_failed(extack._msg);\n+\t\tif (extack._msg)\n+\t\t\tbpf_log(log, \"%s\\n\", extack._msg);\n \t\tgoto out_put_dev;\n \t}\n \n" }
9/2	2026/10/20 00:30	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 11504 output: 10 thoughts: 2340 Thoughts: Analyzing the Crash Report: A Deep Dive Okay, let's break this down. The crash report immediately flags a potential circular locking dependency, which always raises a red flag. It says `syzkaller` thread 20323 is trying to acquire `fs_reclaim` while already holding `&mm->mmap_lock`. My first thought is, this is immediately suspect. `fs_reclaim` shouldn't be acquired while holding `mmap_lock` - that's a classic deadlock scenario. Lockdep is complaining, and that means we have a cycle. Now, let's examine this locking dependency cycle. The chain runs through `fs_reclaim` to `&cpuctx_mutex`, and finally to `&mm->mmap_lock`. That's a classic recipe for a disaster if CPU0 holds mm->mmap_lock and acquires fs_reclaim while CPU1 holds cpuctx_mutex and attempts to grab mm->mmap_lock. I'm concerned about that possible unsafe locking scenario, this is a very clear example of it! I need to understand how `&cpuctx_mutex` comes into play with `&mm->mmap_lock`. Looking at the dependency chain, `perf_ioctl` and `strndup_user` calls within the `&mm->mmap_lock` context are immediately interesting. Is `cpuctx_mutex` held during the `strndup_user` call via `perf_ioctl`? That looks like the smoking gun. This seems to be where the cycle originates. But wait, why is `fs_reclaim` being acquired during a setsockopt call? The stack trace has things like `copy_from_sockptr` and `expand_downwards`. This looks like page faulting, expanding the stack, and allocating maple tree nodes which are all happening under `mmap_lock`, so that feels like it might be the starting point. Looking deeper into the dependency chain gives a clearer picture: * #0: `fs_reclaim` is being acquired during `setsockopt` (specifically when page faulting, expanding stack, and allocating maple tree nodes under mmap_lock). * #1- #9: A complex chain of locks, starting with `q_usage_counter` up to `pmus_lock`. * #10: `mmap_lock` is linked to `cpuctx_mutex`, via `perf_ioctl` holding perf lock/cpuctx_mutex and doing `strndup_user` calls. This is all pretty dense and I need to zoom out a bit. What does this even have to do with the patch series? Let's refresh our memory. So, let's look at the patch series and see what the code changes might indicate: 1. `bpf: Add syscall common attrs support for link_create` 2. `bpf: Add syscall common attrs support for xdp link_create` 3. `bpf: Retire tracepoint bpf_xdp_link_attach_failed` 4. `libbpf: Factor out __sys_bpf_fd helper` 5. `libbpf: Add bpf_link_create_log API` 6. `selftests/bpf: Add tests to verify link_create logs` It looks like the series is focused on BPF link creation and logging, which is relevant to performance tools and tracing. This could be relevant to the `perf_ioctl` and `cpuctx_mutex` angle. The BPF patches are likely interacting with the kernel's memory management or the networking stack in a way that introduces this locking issue. I need to review those patch changes carefully to find the interaction. Time to dig into the diffs...
10/2	2026/10/20 00:30	tool	series-patches	0m Error: missing argument "PatchNum" Args: null Results: { "error": "missing argument \"PatchNum\"" }
11/2	2026/10/20 00:30	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 14699 output: 15 thoughts: 52 Thoughts: Okay, here's my interpretation of those thoughts, tailored for an expert audience, as if they were my own: Navigating Series Patches Alright, so `PatchNum` is either zero or one in this context, right? My initial inclination is to check the `series-patches` file, specifically filtering by `PatchNum=0`. That should give me a good overview of the initial state. Alternatively, I could just jump straight into `git-show` to inspect the contents more directly, especially if I have a particular patch I'm curious about. Hang on a second… I should probably check `PatchNum=1` first. Getting the initial patch out of the way is the right approach. Let's see what's in `series-patches` with that filter. That likely sets the baseline for the comparison.
12/2	2026/10/20 00:30	tool	series-patches	0m Args: { "PatchNum": 1 } Results: { "Output": "Patch [1] [PATCH bpf-next v2 1/6] bpf: Add syscall common attrs support for link_create:\n\nSimilar to the syscall common attrs support for map_create [1], add the\nsyscall common attrs support for link_create.\n\nCreate and finalize the internal verifier log instance.\n\nThen, report the error messages for invalid prog fd, invalid attach type,\nand invalid prog type.\n\nLinks:\n[1] https://lore.kernel.org/bpf/20260514004634.3DA09C19425@smtp.kernel.org/\n\nSigned-off-by: Leon Hwang \u003cleon.hwang@linux.dev\u003e\n---\n include/linux/bpf_verifier.h \| 1 +\n kernel/bpf/log.c \| 19 +++++++++++-------\n kernel/bpf/syscall.c \| 39 ++++++++++++++++++++++++++++++------\n 3 files changed, 46 insertions(+), 13 deletions(-)\n\ndiff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h\nindex 951a90458d18..de9845526ce0 100644\n--- a/include/linux/bpf_verifier.h\n+++ b/include/linux/bpf_verifier.h\n@@ -896,6 +896,7 @@ struct bpf_verifier_log bpf_log_attr_create_vlog(struct bpf_log_attr attr_log,\n \t\t\t\t\t\t struct bpf_common_attr common, bpfptr_t uattr,\n \t\t\t\t\t\t u32 size);\n int bpf_log_attr_finalize(struct bpf_log_attr attr, struct bpf_verifier_log log);\n+int bpf_log_attr_report_size(struct bpf_log_attr attr, u32 size);\n \n #define BPF_MAX_SUBPROGS 256\n \ndiff --git a/kernel/bpf/log.c b/kernel/bpf/log.c\nindex 5432c0fc442b..2bcd62d9ad88 100644\n--- a/kernel/bpf/log.c\n+++ b/kernel/bpf/log.c\n@@ -884,17 +884,22 @@ struct bpf_verifier_log bpf_log_attr_create_vlog(struct bpf_log_attr attr_log,\n \treturn log;\n }\n \n+int bpf_log_attr_report_size(struct bpf_log_attr attr, u32 size)\n+{\n+\tif (attr-\u003eoffsetof_true_size \u0026\u0026\n+\t copy_to_bpfptr_offset(attr-\u003euattr, attr-\u003eoffsetof_true_size, \u0026size, sizeof(size)))\n+\t\treturn -EFAULT;\n+\n+\treturn 0;\n+}\n+\n int bpf_log_attr_finalize(struct bpf_log_attr attr, struct bpf_verifier_log log)\n {\n \tu32 log_true_size;\n-\tint err;\n+\tint err, ret;\n \n \terr = bpf_vlog_finalize(log, \u0026log_true_size);\n \n-\tif (attr-\u003eoffsetof_true_size \u0026\u0026\n-\t copy_to_bpfptr_offset(attr-\u003euattr, attr-\u003eoffsetof_true_size, \u0026log_true_size,\n-\t\t\t\t sizeof(log_true_size)))\n-\t\treturn -EFAULT;\n-\n-\treturn err;\n+\tret = bpf_log_attr_report_size(attr, log_true_size);\n+\treturn ret ? ret : err;\n }\ndiff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c\nindex 849bc9136299..201658b75ab7 100644\n--- a/kernel/bpf/syscall.c\n+++ b/kernel/bpf/syscall.c\n@@ -5856,8 +5856,11 @@ static int bpf_map_do_batch(const union bpf_attr attr,\n }\n \n #define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.path_fd\n-static int link_create(union bpf_attr attr, bpfptr_t uattr)\n+static int link_create(union bpf_attr attr, bpfptr_t uattr, struct bpf_common_attr attr_common,\n+\t\t bpfptr_t uattr_common, u32 size_common)\n {\n+\tstruct bpf_verifier_log log;\n+\tstruct bpf_log_attr attr_log;\n \tstruct bpf_prog prog;\n \tint ret;\n \n@@ -5867,14 +5870,28 @@ static int link_create(union bpf_attr attr, bpfptr_t uattr)\n \tif (attr-\u003elink_create.attach_type == BPF_STRUCT_OPS)\n \t\treturn bpf_struct_ops_link_create(attr);\n \n+\tlog = bpf_log_attr_create_vlog(\u0026attr_log, attr_common, uattr_common, size_common);\n+\tif (IS_ERR(log))\n+\t\treturn PTR_ERR(log);\n+\n \tprog = bpf_prog_get(attr-\u003elink_create.prog_fd);\n-\tif (IS_ERR(prog))\n-\t\treturn PTR_ERR(prog);\n+\tif (IS_ERR(prog)) {\n+\t\tbpf_log(log, \"Invalid prog_fd.\\n\");\n+\t\tret = PTR_ERR(prog);\n+\t\tprog = NULL;\n+\t\tgoto out;\n+\t}\n \n \tret = bpf_prog_attach_check_attach_type(prog,\n \t\t\t\t\t\tattr-\u003elink_create.attach_type);\n-\tif (ret)\n+\tif (ret) {\n+\t\tbpf_log(log, \"Invalid attach_type.\\n\");\n \t\tgoto out;\n+\t}\n+\n+\tret = bpf_log_attr_report_size(\u0026attr_log, 0);\n+\tif (ret)\n+\t\tgoto put_prog;\n \n \tswitch (prog-\u003etype) {\n \tcase BPF_PROG_TYPE_CGROUP_SKB:\n@@ -5953,12 +5970,22 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)\n \t\t\tret = bpf_uprobe_multi_link_attach(attr, prog);\n \t\tbreak;\n \tdefault:\n+\t\tbpf_log(log, \"Invalid prog type.\\n\");\n \t\tret = -EINVAL;\n \t}\n \n out:\n-\tif (ret \u003c 0)\n+\tif (ret \u003c 0) {\n+\t\tint err = bpf_log_attr_finalize(\u0026attr_log, log);\n+\n+\t\tret = err ? err : ret;\n+\t}\n+\n+put_prog:\n+\tif (ret \u003c 0 \u0026\u0026 prog)\n \t\tbpf_prog_put(prog);\n+\n+\tkfree(log);\n \treturn ret;\n }\n \n@@ -6530,7 +6557,7 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size,\n \t\terr = bpf_map_do_batch(\u0026attr, uattr.user, BPF_MAP_DELETE_BATCH);\n \t\tbreak;\n \tcase BPF_LINK_CREATE:\n-\t\terr = link_create(\u0026attr, uattr);\n+\t\terr = link_create(\u0026attr, uattr, \u0026attr_common, uattr_common, size_common);\n \t\tbreak;\n \tcase BPF_LINK_UPDATE:\n \t\terr = link_update(\u0026attr);\n-- \n2.55.0" }
13/2	2026/10/20 00:30	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 16920 output: 15 thoughts: 8 Thoughts: Okay, here's my attempt at summarizing the thought process, tailored for an expert audience, and written in the first person: Analyzing Patch 2 Alright, let's dive into patch 2. My initial reaction is a quick scan for the obvious; any blatant regressions, critical bug fixes, or performance bottlenecks that immediately jump out. I'm looking for the "low-hanging fruit" first – anything that screams "urgent" and needs immediate attention before I even consider the finer points. The structure of the patch itself is what I am considering - are there any unexpected structures or calls that will impact a system architecture? Is the patch well commented? Is the logic easy to follow? From there, I'll start digging deeper, focusing on areas that I know are frequently touched or historically problematic. I'll need to look carefully at the context of changes; I am going to identify the specific components that have been modified and consider the potential ripple effects. Is there a code smell? I'm already mentally running through a battery of unit tests, integration tests, and performance benchmarks that I would expect to be impacted. Now I'll drill down to the more intricate details - the algorithms, the data structures, the error handling, and memory management. I am considering potential concurrency issues and lock contention. Finally, I'll cross-reference the patch with any outstanding issues or previous bug reports to see if there's any overlap or if this patch is addressing related problems. Ultimately, my goal is a comprehensive risk assessment: what's the likelihood of this patch introducing new issues, and what's the potential severity of those issues? I will be looking to see if there are any areas of concern, and if so, how to best address those areas of concern with the appropriate testing strategy.
14/2	2026/10/20 00:30	tool	series-patches	0m Args: { "PatchNum": 2 } Results: { "Output": "Patch [2] [PATCH bpf-next v2 2/6] bpf: Add syscall common attrs support for xdp link_create:\n\nWith the syscall common attrs support for link_create, add syscall common\nattrs support for xdp link_create in order to report the invalid target\nifindex error and the underlying driver's error.\n\nDefine a stub bpf_log() when CONFIG_BPF_SYSCALL is not set. Afterwards,\nbpf_log() can be called without CONFIG_BPF_SYSCALL guard in\nnet/core/dev.c.\n\nSigned-off-by: Leon Hwang \u003cleon.hwang@linux.dev\u003e\n---\n include/linux/bpf_verifier.h \| 5 +++++\n include/linux/netdevice.h \| 3 ++-\n kernel/bpf/syscall.c \| 2 +-\n net/core/dev.c \| 7 ++++++-\n 4 files changed, 14 insertions(+), 3 deletions(-)\n\ndiff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h\nindex de9845526ce0..0b8f764157fc 100644\n--- a/include/linux/bpf_verifier.h\n+++ b/include/linux/bpf_verifier.h\n@@ -1259,8 +1259,13 @@ __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log log,\n \t\t\t\t const char fmt, va_list args);\n __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env env,\n \t\t\t\t\t const char fmt, ...);\n+#ifdef CONFIG_BPF_SYSCALL\n __printf(2, 3) void bpf_log(struct bpf_verifier_log log,\n \t\t\t const char fmt, ...);\n+#else\n+__printf(2, 3) static inline void bpf_log(struct bpf_verifier_log log,\n+\t\t\t\t\t const char fmt, ...) {}\n+#endif\n int bpf_vlog_init(struct bpf_verifier_log log, u32 log_level,\n \t\t char __user log_buf, u32 log_size);\n void bpf_vlog_reset(struct bpf_verifier_log log, u64 new_pos);\ndiff --git a/include/linux/netdevice.h b/include/linux/netdevice.h\nindex 3cff2174dc03..4548b0fd824d 100644\n--- a/include/linux/netdevice.h\n+++ b/include/linux/netdevice.h\n@@ -4417,7 +4417,8 @@ struct sk_buff validate_xmit_skb_list(struct sk_buff skb, struct net_device d\n struct sk_buff dev_hard_start_xmit(struct sk_buff skb, struct net_device dev,\n \t\t\t\t struct netdev_queue txq, int ret);\n \n-int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog);\n+int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog,\n+\t\t\tstruct bpf_verifier_log log);\n u8 dev_xdp_prog_count(struct net_device dev);\n int netif_xdp_propagate(struct net_device dev, struct netdev_bpf bpf);\n int dev_xdp_propagate(struct net_device dev, struct netdev_bpf bpf);\ndiff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c\nindex 201658b75ab7..5652ecf21289 100644\n--- a/kernel/bpf/syscall.c\n+++ b/kernel/bpf/syscall.c\n@@ -5942,7 +5942,7 @@ static int link_create(union bpf_attr attr, bpfptr_t uattr, struct bpf_common_a\n \t\tbreak;\n #ifdef CONFIG_NET\n \tcase BPF_PROG_TYPE_XDP:\n-\t\tret = bpf_xdp_link_attach(attr, prog);\n+\t\tret = bpf_xdp_link_attach(attr, prog, log);\n \t\tbreak;\n \tcase BPF_PROG_TYPE_SCHED_CLS:\n \t\tif (attr-\u003elink_create.attach_type == BPF_TCX_INGRESS \|\|\ndiff --git a/net/core/dev.c b/net/core/dev.c\nindex 18dc88990510..96be63b9331e 100644\n--- a/net/core/dev.c\n+++ b/net/core/dev.c\n@@ -97,6 +97,7 @@\n #include \u003clinux/kthread.h\u003e\n #include \u003clinux/bpf.h\u003e\n #include \u003clinux/bpf_trace.h\u003e\n+#include \u003clinux/bpf_verifier.h\u003e\n #include \u003cnet/net_namespace.h\u003e\n #include \u003cnet/sock.h\u003e\n #include \u003cnet/busy_poll.h\u003e\n@@ -10771,7 +10772,8 @@ static const struct bpf_link_ops bpf_xdp_link_lops = {\n \t.update_prog = bpf_xdp_link_update,\n };\n \n-int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog)\n+int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog,\n+\t\t\tstruct bpf_verifier_log log)\n {\n \tstruct net net = current-\u003ensproxy-\u003enet_ns;\n \tstruct bpf_link_primer link_primer;\n@@ -10784,6 +10786,7 @@ int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog)\n \tdev = dev_get_by_index(net, attr-\u003elink_create.target_ifindex);\n \tif (!dev) {\n \t\trtnl_unlock();\n+\t\tbpf_log(log, \"Invalid target_ifindex.\\n\");\n \t\treturn -EINVAL;\n \t}\n \n@@ -10812,6 +10815,8 @@ int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog)\n \tif (err) {\n \t\tlink-\u003edev = NULL;\n \t\tbpf_link_cleanup(\u0026link_primer);\n+\t\tif (extack._msg)\n+\t\t\tbpf_log(log, \"%s\\n\", extack._msg);\n \t\ttrace_bpf_xdp_link_attach_failed(extack._msg);\n \t\tgoto out_put_dev;\n \t}\n-- \n2.55.0" }
15/2	2026/10/20 00:30	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 19079 output: 15 thoughts: 8 Thoughts: Okay, here's my attempt at summarizing the thought process, tailored for an expert audience, and written in the first person: Analyzing Patch 3 Alright, let's dive into patch 3. Immediately, I'm going to start by looking for the core changes. My initial scan will focus on the areas I expect to be impacted. Considering the existing codebase, I'm guessing this patch likely touches the data access layer and the core algorithm. I need to quickly assess if the changes introduce any obvious regressions or performance bottlenecks. I will be looking at this in the context of the overall system architecture, so any modifications to the data structure are key here. I'll need to scrutinize how it handles edge cases and potential race conditions. I'm mentally preparing to benchmark the changes against our existing performance metrics. That means I will be looking to determine if the changes warrant a deeper dive. There is a need to understand whether these changes are a short-term fix or if they contribute to the system's longer-term viability. I'm especially keen to see if any of these changes are going to impact our established API, and if so, how.
16/2	2026/10/20 00:30	tool	series-patches	0m Args: { "PatchNum": 3 } Results: { "Output": "Patch [3] [PATCH bpf-next v2 3/6] bpf: Retire tracepoint bpf_xdp_link_attach_failed:\n\nIn the previous patch, it has a proper way to back-propagate the\nunderlying driver error message to user space via the BPF syscall common\nattributes.\n\nThe tracepoint bpf_xdp_link_attach_failed seems redundant to report the\nerror message. And, the tracepoint doesn't report the ifindex alongside\nthe error message [1].\n\nSo, retire the tracepoint bpf_xdp_link_attach_failed and its selftest.\n\nAccording to the tracepoint change discussion [2], please revert this\npatch if users complain about the disappeared tracepoint\nbpf_xdp_link_attach_failed in the future.\n\nLinks:\n[1] https://lore.kernel.org/bpf/CAFk-A4mE9Jweo2hfX7y_85xbPyt0FqpMT1EvqX1OcYZ=LTLgRA@mail.gmail.com/\n[2] https://lore.kernel.org/linux-mm/CY8PR11MB7134346A3E4BB28ECA28D6E989132@CY8PR11MB7134.namprd11.prod.outlook.com/\n\nSigned-off-by: Leon Hwang \u003cleon.hwang@linux.dev\u003e\n---\n include/trace/events/xdp.h \| 17 -----\n net/core/dev.c \| 1 -\n .../selftests/bpf/prog_tests/xdp_attach.c \| 65 -------------------\n .../bpf/progs/test_xdp_attach_fail.c \| 54 ---------------\n 4 files changed, 137 deletions(-)\n delete mode 100644 tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c\n\ndiff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h\nindex 18c0ac514fcb..f1d4d0702884 100644\n--- a/include/trace/events/xdp.h\n+++ b/include/trace/events/xdp.h\n@@ -362,23 +362,6 @@ TRACE_EVENT(mem_connect,\n \t)\n );\n \n-TRACE_EVENT(bpf_xdp_link_attach_failed,\n-\n-\tTP_PROTO(const char msg),\n-\n-\tTP_ARGS(msg),\n-\n-\tTP_STRUCT__entry(\n-\t\t__string(msg, msg)\n-\t),\n-\n-\tTP_fast_assign(\n-\t\t__assign_str(msg);\n-\t),\n-\n-\tTP_printk(\"errmsg=%s\", __get_str(msg))\n-);\n-\n #endif / _TRACE_XDP_H /\n \n #include \u003ctrace/define_trace.h\u003e\ndiff --git a/net/core/dev.c b/net/core/dev.c\nindex 96be63b9331e..a142613536b0 100644\n--- a/net/core/dev.c\n+++ b/net/core/dev.c\n@@ -10817,7 +10817,6 @@ int bpf_xdp_link_attach(const union bpf_attr attr, struct bpf_prog prog,\n \t\tbpf_link_cleanup(\u0026link_primer);\n \t\tif (extack._msg)\n \t\t\tbpf_log(log, \"%s\\n\", extack._msg);\n-\t\ttrace_bpf_xdp_link_attach_failed(extack._msg);\n \t\tgoto out_put_dev;\n \t}\n \ndiff --git a/tools/testing/selftests/bpf/prog_tests/xdp_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_attach.c\nindex e6bcb6051402..fa3cac5488f5 100644\n--- a/tools/testing/selftests/bpf/prog_tests/xdp_attach.c\n+++ b/tools/testing/selftests/bpf/prog_tests/xdp_attach.c\n@@ -1,6 +1,5 @@\n // SPDX-License-Identifier: GPL-2.0\n #include \u003ctest_progs.h\u003e\n-#include \"test_xdp_attach_fail.skel.h\"\n \n #define IFINDEX_LO 1\n #define XDP_FLAGS_REPLACE\t\t(1U \u003c\u003c 4)\n@@ -86,74 +85,10 @@ static void test_xdp_attach(const char file)\n \tbpf_object__close(obj1);\n }\n \n-#define ERRMSG_LEN 64\n-\n-struct xdp_errmsg {\n-\tchar msg[ERRMSG_LEN];\n-};\n-\n-static void on_xdp_errmsg(void ctx, int cpu, void data, __u32 size)\n-{\n-\tstruct xdp_errmsg ctx_errmg = ctx, tp_errmsg = data;\n-\n-\tmemcpy(\u0026ctx_errmg-\u003emsg, \u0026tp_errmsg-\u003emsg, ERRMSG_LEN);\n-}\n-\n-static const char tgt_errmsg[] = \"Invalid XDP flags for BPF link attachment\";\n-\n-static void test_xdp_attach_fail(const char file)\n-{\n-\tstruct test_xdp_attach_fail skel = NULL;\n-\tstruct xdp_errmsg errmsg = {};\n-\tstruct perf_buffer pb = NULL;\n-\tstruct bpf_object obj = NULL;\n-\tint err, fd_xdp;\n-\n-\tLIBBPF_OPTS(bpf_link_create_opts, opts);\n-\n-\tskel = test_xdp_attach_fail__open_and_load();\n-\tif (!ASSERT_OK_PTR(skel, \"test_xdp_attach_fail__open_and_load\"))\n-\t\tgoto out_close;\n-\n-\terr = test_xdp_attach_fail__attach(skel);\n-\tif (!ASSERT_EQ(err, 0, \"test_xdp_attach_fail__attach\"))\n-\t\tgoto out_close;\n-\n-\t/* set up perf buffer /\n-\tpb = perf_buffer__new(bpf_map__fd(skel-\u003emaps.xdp_errmsg_pb), 1,\n-\t\t\t on_xdp_errmsg, NULL, \u0026errmsg, NULL);\n-\tif (!ASSERT_OK_PTR(pb, \"perf_buffer__new\"))\n-\t\tgoto out_close;\n-\n-\terr = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, \u0026obj, \u0026fd_xdp);\n-\tif (!ASSERT_EQ(err, 0, \"bpf_prog_test_load\"))\n-\t\tgoto out_close;\n-\n-\topts.flags = 0xFF; // invalid flags to fail to attach XDP prog\n-\terr = bpf_link_create(fd_xdp, IFINDEX_LO, BPF_XDP, \u0026opts);\n-\tif (!ASSERT_EQ(err, -EINVAL, \"bpf_link_create\"))\n-\t\tgoto out_close;\n-\n-\t/ read perf buffer /\n-\terr = perf_buffer__poll(pb, 100);\n-\tif (!ASSERT_GT(err, -1, \"perf_buffer__poll\"))\n-\t\tgoto out_close;\n-\n-\tASSERT_STRNEQ((const char ) errmsg.msg, tgt_errmsg,\n-\t\t 42 /* strlen(tgt_errmsg) /, \"check error message\");\n-\n-out_close:\n-\tperf_buffer__free(pb);\n-\tbpf_object__close(obj);\n-\ttest_xdp_attach_fail__destroy(skel);\n-}\n-\n void serial_test_xdp_attach(void)\n {\n \tif (test__start_subtest(\"xdp_attach\"))\n \t\ttest_xdp_attach(\"./test_xdp.bpf.o\");\n \tif (test__start_subtest(\"xdp_attach_dynptr\"))\n \t\ttest_xdp_attach(\"./test_xdp_dynptr.bpf.o\");\n-\tif (test__start_subtest(\"xdp_attach_failed\"))\n-\t\ttest_xdp_attach_fail(\"./xdp_dummy.bpf.o\");\n }\ndiff --git a/tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c b/tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c\ndeleted file mode 100644\nindex 2ff1b596e87e..000000000000\n--- a/tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c\n+++ /dev/null\n@@ -1,54 +0,0 @@\n-// SPDX-License-Identifier: GPL-2.0\n-/ Copyright Leon Hwang /\n-\n-#include \u003clinux/bpf.h\u003e\n-#include \u003cbpf/bpf_helpers.h\u003e\n-\n-#define ERRMSG_LEN 64\n-\n-struct xdp_errmsg {\n-\tchar msg[ERRMSG_LEN];\n-};\n-\n-struct {\n-\t__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);\n-\t__type(key, int);\n-\t__type(value, int);\n-} xdp_errmsg_pb SEC(\".maps\");\n-\n-struct xdp_attach_error_ctx {\n-\tunsigned long unused;\n-\n-\t/\n-\t * bpf does not support tracepoint __data_loc directly.\n-\t \n-\t Actually, this field is a 32 bit integer whose value encodes\n-\t * information on where to find the actual data. The first 2 bytes is\n-\t * the size of the data. The last 2 bytes is the offset from the start\n-\t * of the tracepoint struct where the data begins.\n-\t * -- https://github.com/iovisor/bpftrace/pull/1542\n-\t /\n-\t__u32 msg; // __data_loc char[] msg;\n-};\n-\n-/\n- * Catch the error message at the tracepoint.\n- /\n-\n-SEC(\"tp/xdp/bpf_xdp_link_attach_failed\")\n-int tp__xdp__bpf_xdp_link_attach_failed(struct xdp_attach_error_ctx ctx)\n-{\n-\tchar msg = (void )(__u64) ((void ) ctx + (__u16) ctx-\u003emsg);\n-\tstruct xdp_errmsg errmsg = {};\n-\n-\tbpf_probe_read_kernel_str(\u0026errmsg.msg, ERRMSG_LEN, msg);\n-\tbpf_perf_event_output(ctx, \u0026xdp_errmsg_pb, BPF_F_CURRENT_CPU, \u0026errmsg,\n-\t\t\t ERRMSG_LEN);\n-\treturn 0;\n-}\n-\n-/\n- * Reuse the XDP program in xdp_dummy.c.\n- */\n-\n-char LICENSE[] SEC(\"license\") = \"GPL\";\n-- \n2.55.0" }
17/2	2026/10/20 00:30	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 22173 output: 15 thoughts: 16 Thoughts: Okay, here's my attempt at summarizing the thought process, tailored for an expert audience, and written in the first person: Expanding the Scope of Investigation Alright, I've got a decent handle on patches 1, 2, and 3, and I've identified some initial correlations/anomalies. But I can't jump to any firm conclusions yet; I need to broaden my scope to ensure I'm seeing the full picture. My immediate thought is to include patches 4, 5, and 6 in the investigation. There's a high probability that whatever findings I find in 1-3, will be relevant to, or affected by, changes present in the subsequent patches. Ignoring them at this stage would be a critical oversight, potentially leading to incomplete or misleading results. I need to ensure a complete understanding, especially considering potential dependencies or interactions across versions. I'm thinking I can likely use the same set of evaluation criteria from the original analysis. This should ensure efficiency while maintaining thoroughness.
18/2	2026/10/20 00:30	tool	series-patches	0m Args: { "PatchNum": 4 } Results: { "Output": "Patch [4] [PATCH bpf-next v2 4/6] libbpf: Factor out __sys_bpf_fd helper:\n\nIn the next patch, it also needs to use the extended BPF syscall to\nreceive the reported log.\n\nSo, factor out __sys_bpf_fd helper.\n\nNo functional changes intended.\n\nSigned-off-by: Leon Hwang \u003cleon.hwang@linux.dev\u003e\n---\n tools/lib/bpf/bpf.c \| 41 +++++++++++++++++++++++++----------------\n 1 file changed, 25 insertions(+), 16 deletions(-)\n\ndiff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c\nindex b49822d212ae..9a2107d4f6d8 100644\n--- a/tools/lib/bpf/bpf.c\n+++ b/tools/lib/bpf/bpf.c\n@@ -203,6 +203,30 @@ int bump_rlimit_memlock(void)\n \treturn 0;\n }\n \n+static int __sys_bpf_fd(union bpf_attr attr, const size_t attr_sz, enum bpf_cmd cmd,\n+\t\t\tstruct bpf_log_opts log_opts)\n+{\n+\tconst size_t attr_common_sz = sizeof(struct bpf_common_attr);\n+\tstruct bpf_common_attr attr_common;\n+\tint fd;\n+\n+\tif (!OPTS_VALID(log_opts, bpf_log_opts))\n+\t\treturn libbpf_err(-EINVAL);\n+\n+\tif (log_opts \u0026\u0026 feat_supported(NULL, FEAT_BPF_SYSCALL_COMMON_ATTRS)) {\n+\t\tmemset(\u0026attr_common, 0, attr_common_sz);\n+\t\tattr_common.log_buf = ptr_to_u64(OPTS_GET(log_opts, buf, NULL));\n+\t\tattr_common.log_size = OPTS_GET(log_opts, size, 0);\n+\t\tattr_common.log_level = OPTS_GET(log_opts, level, 0);\n+\t\tfd = sys_bpf_ext_fd(cmd, attr, attr_sz, \u0026attr_common, attr_common_sz);\n+\t\tOPTS_SET(log_opts, true_size, attr_common.log_true_size);\n+\t} else {\n+\t\tfd = sys_bpf_fd(cmd, attr, attr_sz);\n+\t\tOPTS_SET(log_opts, true_size, 0);\n+\t}\n+\treturn fd;\n+}\n+\n int bpf_map_create(enum bpf_map_type map_type,\n \t\t const char map_name,\n \t\t __u32 key_size,\n@@ -211,8 +235,6 @@ int bpf_map_create(enum bpf_map_type map_type,\n \t\t const struct bpf_map_create_opts opts)\n {\n \tconst size_t attr_sz = offsetofend(union bpf_attr, excl_prog_hash_size);\n-\tconst size_t attr_common_sz = sizeof(struct bpf_common_attr);\n-\tstruct bpf_common_attr attr_common;\n \tstruct bpf_log_opts *log_opts;\n \tunion bpf_attr attr;\n \tint fd;\n@@ -248,20 +270,7 @@ int bpf_map_create(enum bpf_map_type map_type,\n \tattr.excl_prog_hash_size = OPTS_GET(opts, excl_prog_hash_size, 0);\n \n \tlog_opts = OPTS_GET(opts, log_opts, NULL);\n-\tif (!OPTS_VALID(log_opts, bpf_log_opts))\n-\t\treturn libbpf_err(-EINVAL);\n-\n-\tif (log_opts \u0026\u0026 feat_supported(NULL, FEAT_BPF_SYSCALL_COMMON_ATTRS)) {\n-\t\tmemset(\u0026attr_common, 0, attr_common_sz);\n-\t\tattr_common.log_buf = ptr_to_u64(OPTS_GET(log_opts, buf, NULL));\n-\t\tattr_common.log_size = OPTS_GET(log_opts, size, 0);\n-\t\tattr_common.log_level = OPTS_GET(log_opts, level, 0);\n-\t\tfd = sys_bpf_ext_fd(BPF_MAP_CREATE, \u0026attr, attr_sz, \u0026attr_common, attr_common_sz);\n-\t\tOPTS_SET(log_opts, true_size, attr_common.log_true_size);\n-\t} else {\n-\t\tfd = sys_bpf_fd(BPF_MAP_CREATE, \u0026attr, attr_sz);\n-\t\tOPTS_SET(log_opts, true_size, 0);\n-\t}\n+\tfd = __sys_bpf_fd(\u0026attr, attr_sz, BPF_MAP_CREATE, log_opts);\n \treturn libbpf_err_errno(fd);\n }\n \n-- \n2.55.0" }
19/2	2026/10/20 00:30	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 23705 output: 15 thoughts: 11 Thoughts: Okay, here's my interpretation of "Let's see patch 5 and 6", tailored for an expert audience, as if it's my own thought process: Diving into Patch 5 and 6 Alright, let's get down to brass tacks. "Patch 5 and 6"... that immediately signals a specific level of detail. I'm not just looking at a general overview. I'm gearing up to analyze a distinct set of updates, probably related. The implication is these patches are significant enough to warrant focused attention. Depending on the context I might wonder if these are related to a known bug, a feature release, or security updates. I need to understand the prior context to get the most from these patches. My initial thought is to identify the scope of these patches. Are they comprehensive in their changes or only limited? What are the implications of the changes in terms of performance, security, and compatibility? I'll probably start by checking the release notes and changelogs. Those will give me the high-level picture. From there, I'll drill down into the specifics that seem most relevant to my immediate concerns.
20/2	2026/10/20 00:30	tool	series-patches	0m Args: { "PatchNum": 5 } Results: { "Output": "Patch [5] [PATCH bpf-next v2 5/6] libbpf: Add bpf_link_create_log API:\n\nAdd a new API to accept the log opts, instead of extending the existing\nstruct bpf_link_create_opts.\n\nAppending log_opts to struct bpf_link_create_opts would place them after\nattach-type-specific fields of varying sizes, making it difficult to\nextend the struct while preserving forward compatibility.\n\nFor example, adding log_opts would prevent extending uprobe_multi\ndirectly with a new build_id field. Instead, a separate union would\nbe needed:\n\nstruct bpf_link_create_opts {\n /* ... /\n union {\n / ... /\n struct {\n / ... /\n __u32 path_fd;\n } uprobe_multi;\n };\n struct bpf_log_opts log_opts;\n union {\n struct {\n __u64 build_id;\n } uprobe_multi_ext;\n };\n size_t :0;\n};\n\nWithout log_opts, build_id could be added directly to uprobe_multi:\n\nstruct bpf_link_create_opts {\n /* ... /\n union {\n / ... /\n struct {\n / ... /\n __u32 path_fd;\n __u64 build_id;\n } uprobe_multi;\n };\n size_t :0;\n};\n\nIntroduce bpf_link_create_log() to accept struct bpf_log_opts separately,\npreserving the forward compatibility of struct bpf_link_create_opts.\n\nSigned-off-by: Leon Hwang \u003cleon.hwang@linux.dev\u003e\n---\n tools/lib/bpf/bpf.c \| 28 ++++++++++++++++++++++++----\n tools/lib/bpf/bpf.h \| 5 +++++\n tools/lib/bpf/libbpf.map \| 2 ++\n 3 files changed, 31 insertions(+), 4 deletions(-)\n\ndiff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c\nindex 9a2107d4f6d8..263a1d516a02 100644\n--- a/tools/lib/bpf/bpf.c\n+++ b/tools/lib/bpf/bpf.c\n@@ -788,9 +788,10 @@ int bpf_prog_detach2(int prog_fd, int target_fd, enum bpf_attach_type type)\n \treturn bpf_prog_detach_opts(prog_fd, target_fd, type, NULL);\n }\n \n-int bpf_link_create(int prog_fd, int target_fd,\n-\t\t enum bpf_attach_type attach_type,\n-\t\t const struct bpf_link_create_opts opts)\n+static int __bpf_link_create(int prog_fd, int target_fd,\n+\t\t\t enum bpf_attach_type attach_type,\n+\t\t\t const struct bpf_link_create_opts opts,\n+\t\t\t struct bpf_log_opts log_opts)\n {\n \tconst size_t attr_sz = offsetofend(union bpf_attr, link_create);\n \t__u32 target_btf_id, iter_info_len, relative_id;\n@@ -965,7 +966,7 @@ int bpf_link_create(int prog_fd, int target_fd,\n \t\tbreak;\n \t}\n proceed:\n-\tfd = sys_bpf_fd(BPF_LINK_CREATE, \u0026attr, attr_sz);\n+\tfd = __sys_bpf_fd(\u0026attr, attr_sz, BPF_LINK_CREATE, log_opts);\n \tif (fd \u003e= 0)\n \t\treturn fd;\n \t/* we'll get EINVAL if LINK_CREATE doesn't support attaching fentry\n@@ -975,6 +976,10 @@ int bpf_link_create(int prog_fd, int target_fd,\n \tif (err != -EINVAL)\n \t\treturn libbpf_err(err);\n \n+\t/* bpf_raw_tracepoint_open() does not support log_opts /\n+\tif (log_opts)\n+\t\treturn libbpf_err(err);\n+\n \t/ if user used features not supported by\n \t * BPF_RAW_TRACEPOINT_OPEN command, then just give up immediately\n \t /\n@@ -999,6 +1004,21 @@ int bpf_link_create(int prog_fd, int target_fd,\n \t}\n }\n \n+int bpf_link_create(int prog_fd, int target_fd,\n+\t\t enum bpf_attach_type attach_type,\n+\t\t const struct bpf_link_create_opts opts)\n+{\n+\treturn __bpf_link_create(prog_fd, target_fd, attach_type, opts, NULL);\n+}\n+\n+int bpf_link_create_log(int prog_fd, int target_fd,\n+\t\t\tenum bpf_attach_type attach_type,\n+\t\t\tconst struct bpf_link_create_opts opts,\n+\t\t\tstruct bpf_log_opts log_opts)\n+{\n+\treturn __bpf_link_create(prog_fd, target_fd, attach_type, opts, log_opts);\n+}\n+\n int bpf_link_detach(int link_fd)\n {\n \tconst size_t attr_sz = offsetofend(union bpf_attr, link_detach);\ndiff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h\nindex 826d9cc9ab65..dedaf8086902 100644\n--- a/tools/lib/bpf/bpf.h\n+++ b/tools/lib/bpf/bpf.h\n@@ -484,6 +484,11 @@ LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,\n \t\t\t enum bpf_attach_type attach_type,\n \t\t\t const struct bpf_link_create_opts opts);\n \n+LIBBPF_API int bpf_link_create_log(int prog_fd, int target_fd,\n+\t\t\t\t enum bpf_attach_type attach_type,\n+\t\t\t\t const struct bpf_link_create_opts opts,\n+\t\t\t\t struct bpf_log_opts *log_opts);\n+\n LIBBPF_API int bpf_link_detach(int link_fd);\n \n struct bpf_link_update_opts {\ndiff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map\nindex eeba4072a5da..f6eb57151f7d 100644\n--- a/tools/lib/bpf/libbpf.map\n+++ b/tools/lib/bpf/libbpf.map\n@@ -475,4 +475,6 @@ LIBBPF_1.8.0 {\n } LIBBPF_1.7.0;\n \n LIBBPF_1.9.0 {\n+\tglobal:\n+\t\tbpf_link_create_log;\n } LIBBPF_1.8.0;\n-- \n2.55.0" }
21/2	2026/10/20 00:30	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 25805 output: 15 thoughts: 9 Thoughts: Okay, here's the summary, rendered as a first-person thought process assuming the user is an expert. Checking Patch 6 - A Preliminary Assessment Alright, let's dive into patch 6. I need to quickly assess this, probably with my established workflow. I'll be looking for the obvious red flags – any immediate regressions, glaring performance bottlenecks, or critical security vulnerabilities that jump out. Based on the changelog or release notes, my initial focus will be on the areas that have undergone significant modifications. This initial pass won't be exhaustive, but it needs to identify the 'showstoppers' – the things that would prevent immediate deployment or require an emergency rollback. I'll need to correlate the changes against the relevant documentation and potentially previous test data or simulations to assess the impact. If everything looks clean, I'll schedule a deeper dive later, but I need to quickly form a preliminary opinion on the patch. Let's see what we're working with here.
22/2	2026/10/20 00:30	tool	series-patches	0m Args: { "PatchNum": 6 } Results: { "Output": "Patch [6] [PATCH bpf-next v2 6/6] selftests/bpf: Add tests to verify link_create logs:\n\nAdd tests to verify the new logs in link_create and xdp link_create,\nincluding a log reported via extack when fail to create an xdp link.\n\nSigned-off-by: Leon Hwang \u003cleon.hwang@linux.dev\u003e\n---\n .../selftests/bpf/prog_tests/xdp_link.c \| 101 ++++++++++++++++++\n 1 file changed, 101 insertions(+)\n\ndiff --git a/tools/testing/selftests/bpf/prog_tests/xdp_link.c b/tools/testing/selftests/bpf/prog_tests/xdp_link.c\nindex e7e9f3c22edf..18c1f1039d4e 100644\n--- a/tools/testing/selftests/bpf/prog_tests/xdp_link.c\n+++ b/tools/testing/selftests/bpf/prog_tests/xdp_link.c\n@@ -150,3 +150,104 @@ void serial_test_xdp_link(void)\n \ttest_xdp_link__destroy(skel1);\n \ttest_xdp_link__destroy(skel2);\n }\n+\n+static void test_link_create(int prog_fd, int ifindex, enum bpf_attach_type attach_type,\n+\t\t\t struct bpf_link_create_opts opts, int exp_err, const char msg)\n+{\n+\tchar log_buf[128] = {};\n+\tint fd;\n+\tLIBBPF_OPTS(bpf_log_opts, log_opts,\n+\t\t .buf = log_buf,\n+\t\t .size = sizeof(log_buf),\n+\t\t .level = 1,\n+\t);\n+\n+\tfd = bpf_link_create_log(prog_fd, ifindex, attach_type, opts, \u0026log_opts);\n+\tif (!ASSERT_LT(fd, 0, \"bpf_link_create_log\")) {\n+\t\tclose(fd);\n+\t\treturn;\n+\t}\n+\n+\tASSERT_EQ(fd, exp_err, \"fd\");\n+\tASSERT_STREQ(log_buf, msg, \"log_buf\");\n+\tASSERT_EQ(log_opts.true_size, strlen(msg) + 1, \"log_size\");\n+}\n+\n+static void test_link_create_invalid_prog_fd(void)\n+{\n+\tconst char msg = \"Invalid prog_fd.\\n\";\n+\n+\ttest_link_create(-1, IFINDEX_LO, BPF_XDP, NULL, -EBADF, msg);\n+}\n+\n+static void test_link_create_invalid_prog_type(void)\n+{\n+\tconst struct bpf_insn insns[] = {\n+\t\tBPF_MOV64_IMM(BPF_REG_0, 0),\n+\t\tBPF_EXIT_INSN(),\n+\t};\n+\tconst char msg = \"Invalid prog type.\\n\";\n+\tint prog_fd;\n+\n+\tprog_fd = bpf_prog_load(BPF_PROG_TYPE_LIRC_MODE2, NULL, \"GPL\", insns,\n+\t\t\t\tARRAY_SIZE(insns), NULL);\n+\tif (!ASSERT_GE(prog_fd, 0, \"bpf_prog_load\"))\n+\t\treturn;\n+\n+\ttest_link_create(prog_fd, 0, BPF_LIRC_MODE2, NULL, -EINVAL, msg);\n+\n+\tclose(prog_fd);\n+}\n+\n+static void test_link_create_attach(int ifindex, enum bpf_attach_type attach_type,\n+\t\t\t\t struct bpf_link_create_opts opts, const char msg)\n+{\n+\tstruct test_xdp_link skel;\n+\n+\tskel = test_xdp_link__open_and_load();\n+\tif (!ASSERT_OK_PTR(skel, \"test_xdp_link__open_and_load\"))\n+\t\treturn;\n+\n+\ttest_link_create(bpf_program__fd(skel-\u003eprogs.xdp_handler), ifindex, attach_type, opts,\n+\t\t\t -EINVAL, msg);\n+\n+\ttest_xdp_link__destroy(skel);\n+}\n+\n+static void test_link_create_invalid_attach_type(void)\n+{\n+\tconst char msg = \"Invalid attach_type.\\n\";\n+\n+\ttest_link_create_attach(IFINDEX_LO, BPF_CGROUP_INET_INGRESS, NULL, msg);\n+}\n+\n+static void test_link_create_xdp_invalid_target_ifindex(void)\n+{\n+\tconst char msg = \"Invalid target_ifindex.\\n\";\n+\n+\ttest_link_create_attach(0, BPF_XDP, NULL, msg);\n+}\n+\n+static void test_link_create_xdp_extack(void)\n+{\n+\tconst char msg = \"Invalid XDP flags for BPF link attachment\\n\";\n+\tLIBBPF_OPTS(bpf_link_create_opts, opts,\n+\t\t .flags = XDP_FLAGS_REPLACE,\n+\t);\n+\n+\ttest_link_create_attach(IFINDEX_LO, BPF_XDP, \u0026opts, msg);\n+}\n+\n+void test_link_create_log(void)\n+{\n+\tif (test__start_subtest(\"invalid_prog_fd\"))\n+\t\ttest_link_create_invalid_prog_fd();\n+\tif (test__start_subtest(\"invalid_prog_type\"))\n+\t\ttest_link_create_invalid_prog_type();\n+\tif (test__start_subtest(\"invalid_attach_type\"))\n+\t\ttest_link_create_invalid_attach_type();\n+\tif (test__start_subtest(\"xdp/invalid_target_ifindex\"))\n+\t\ttest_link_create_xdp_invalid_target_ifindex();\n+\tif (test__start_subtest(\"xdp/extack\"))\n+\t\ttest_link_create_xdp_extack();\n+}\n-- \n2.55.0" }
23/2	2026/10/20 00:30	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 27600 output: 23 thoughts: 1160 Thoughts: Analyzing a Lock Dependency Issue Okay, let's break this down. First, I need to understand the context. The patch series seems to be adding logging capabilities to BPF links and related functions, including some libbpf and selftest updates. It looks like the team is making changes to how BPF errors are logged. Now, the crash report. This is a classic lockdep warning: a possible circular locking dependency. Let me walk through this step-by-step. The report highlights that syzkaller is triggering this, specifically during a `setsockopt()` call with something related to `MRT_ADD_VIF` or similar (likely multicast routing). The crucial path is this: within the `setsockopt` call, we have `copy_from_sockptr()`, which uses `_copy_from_user()`. This triggers a page fault. The kernel then handles this fault in `do_user_addr_fault()`. This code attempts to acquire the `&mm->mmap_lock` (read lock), which it then holds or upgrades. This is where things get interesting. From there, `expand_downwards()` eventually calls `kmem_cache_alloc_noprof()` which, because of `GFP_KERNEL`, can trigger memory reclaim involving the `fs_reclaim` lock. Lockdep detects that `fs_reclaim` now depends on `&mm->mmap_lock`. Here's the problem: lockdep has traced a long chain of dependencies that creates a circular relationship. `fs_reclaim` is trying to depend on the `&mm->mmap_lock` read lock, but the call stack shows that `&mm->mmap_lock` is already being held or upgraded! The chain traced back is quite long and traverses various parts of the kernel, including block devices, network block devices (NBD), and even performance monitoring. The complete reverse chain is `fs_reclaim` -> `q_usage_counter` -> `q->elevator_lock` -> `set->srcu` -> `cmd->lock` -> `nsock->tx_lock` -> `cpu_hotplug_lock` -> `cpuhp_state-up` -> `pmus_lock` -> `cpuctx_mutex` -> `&mm->mmap_lock`. This means `&mm->mmap_lock` is acquired earlier than it should be in relation to `fs_reclaim`. My question is: is this a known issue? I need to check the kernel's history. Has anyone else encountered a circular locking dependency like this involving `perf_ioctl`, `mmap_lock`, `cpuctx_mutex`, or `fs_reclaim`? Let's search the git log and online issues for clues. Time to dig into the kernel source and see if this has been encountered before, or if this is something new that our changes have introduced.
24/2	2026/10/20 00:31	tool	grepper	0m Error: no matches Args: { "Expression": "perf_ioctl.strndup_user" } Results:* { "error": "no matches" }
25/2	2026/10/20 00:31	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29424 output: 33 thoughts: 19 Thoughts: Okay, let's dive into this. Here's my thought process on tackling this: Analyzing `perf_ioctl` in `kernel/events/core.c` Alright, time to get to it. I need to take a look at `perf_ioctl` in `kernel/events/core.c`. This means I'm probably dealing with user-space interactions with the performance monitoring subsystem, likely through ioctl calls. This is a crucial area, as it's the gatekeeper for controlling and configuring performance counters. I'll need to examine how these ioctls are implemented, what data structures they interact with, and any potential security implications or performance bottlenecks within the core event framework. I'll be particularly interested in how events are started, stopped, configured, and how data is read back. I expect this function will be a hub, dispatching based on an ioctl command ID. I should be able to quickly understand the control flow and identify relevant data structure access. I'll be looking for common things like locking, error handling, and any interesting event filtering or sampling logic. I'm hoping to get a good understanding of how the perf infrastructure is controlled from the user level to help diagnose a related issue.
26/2	2026/10/20 00:31	tool	grepper	0m Args: { "Expression": "strndup_user", "PathPrefixes": [ "kernel/events/core.c" ] } Results: { "Output": "kernel/events/core.c=12254=static int perf_event_set_filter(struct perf_event event, void __user arg)\n--\nkernel/events/core.c-12258-\nkernel/events/core.c:12259:\tfilter_str = strndup_user(arg, PAGE_SIZE);\nkernel/events/core.c-12260-\tif (IS_ERR(filter_str))\n" }
27/2	2026/10/20 00:31	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29859 output: 37 thoughts: 26 Thoughts: Okay, let's dive into this. Here's how I'd approach summarizing the prompt, keeping in mind I'm dealing with someone who understands kernel internals: Diving Deep into `perf_event_set_filter` Alright, my focus is now on `perf_event_set_filter` and its interactions. I'm going to head over to `kernel/events/core.c` immediately. My first thought is to understand the context of this function. I need to grasp how filters are established and modified within the performance events subsystem. What specific data structures does `perf_event_set_filter` operate on? Where does the filter string come from? Are there any security considerations or potential race conditions I should be immediately aware of? I'll quickly scan the callers of this function to understand the different entry points for setting or modifying filters. Are these calls synchronous or asynchronous? Are there any notable patterns in the calling context that might offer clues about usage scenarios (e.g., user-space interactions, internal kernel control flows)? I'll be particularly interested in identifying any potential areas where incorrect filter settings could lead to performance bottlenecks or unexpected behavior. Essentially, I'm trying to visualize the call graph and the logical flow that this function embodies, to get a sense of its overall impact within the event subsystem.
28/2	2026/10/20 00:31	tool	read-file	0m Args: { "File": "kernel/events/core.c", "FirstLine": 12250, "LineCount": 40 } Results: { "Contents": "12250:\t\n12251:\t\treturn ret;\n12252:\t}\n12253:\t\n12254:\tstatic int perf_event_set_filter(struct perf_event event, void __user arg)\n12255:\t{\n12256:\t\tint ret = -EINVAL;\n12257:\t\tchar filter_str;\n12258:\t\n12259:\t\tfilter_str = strndup_user(arg, PAGE_SIZE);\n12260:\t\tif (IS_ERR(filter_str))\n12261:\t\t\treturn PTR_ERR(filter_str);\n12262:\t\n12263:\t#ifdef CONFIG_EVENT_TRACING\n12264:\t\tif (perf_event_is_tracing(event)) {\n12265:\t\t\tstruct perf_event_context ctx = event-\u003ectx;\n12266:\t\n12267:\t\t\t/\n12268:\t\t\t Beware, here be dragons!!\n12269:\t\t\t \n12270:\t\t\t the tracepoint muck will deadlock against ctx-\u003emutex, but\n12271:\t\t\t * the tracepoint stuff does not actually need it. So\n12272:\t\t\t * temporarily drop ctx-\u003emutex. As per perf_event_ctx_lock() we\n12273:\t\t\t * already have a reference on ctx.\n12274:\t\t\t \n12275:\t\t\t This can result in event getting moved to a different ctx,\n12276:\t\t\t * but that does not affect the tracepoint state.\n12277:\t\t\t */\n12278:\t\t\tmutex_unlock(\u0026ctx-\u003emutex);\n12279:\t\t\tret = ftrace_profile_set_filter(event, event-\u003eattr.config, filter_str);\n12280:\t\t\tmutex_lock(\u0026ctx-\u003emutex);\n12281:\t\t} else\n12282:\t#endif\n12283:\t\tif (has_addr_filter(event))\n12284:\t\t\tret = perf_event_set_addr_filter(event, filter_str);\n12285:\t\n12286:\t\tkfree(filter_str);\n12287:\t\treturn ret;\n12288:\t}\n12289:\t\n" }
29/2	2026/10/20 00:31	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 30812 output: 35 thoughts: 30 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, presented in the first person: Diving into `perf_ioctl` and Filter Setting Alright, let's get down to brass tacks. I need to understand how filtering works within the `perf` subsystem, so I'm focusing my attention on `perf_ioctl`. My primary goal is to trace the call paths of `perf_event_set_filter`. I want to figure out all the possible locations within `perf_ioctl` where the `perf_event_set_filter` routine could be called from. I'm assuming that it is called from one place. I'll need to follow the control flow closely to see how the filtering mechanism is integrated. I'm expecting this will give me a better handle on the kernel's approach to implementing filters at the event level.
30/2	2026/10/20 00:31	tool	grepper	0m Args: { "Expression": "perf_event_set_filter", "PathPrefixes": [ "kernel/events/core.c" ] } Results: { "Output": "kernel/events/core.c=6606=static int perf_event_set_output(struct perf_event event,\nkernel/events/core.c-6607-\t\t\t\t struct perf_event output_event);\nkernel/events/core.c:6608:static int perf_event_set_filter(struct perf_event event, void __user arg);\nkernel/events/core.c-6609-static int perf_copy_attr(struct perf_event_attr __user uattr,\n--\nkernel/events/core.c=6615=static long _perf_ioctl(struct perf_event event, unsigned int cmd, unsigned long arg)\n--\nkernel/events/core.c-6667-\tcase PERF_EVENT_IOC_SET_FILTER:\nkernel/events/core.c:6668:\t\treturn perf_event_set_filter(event, (void __user )arg);\nkernel/events/core.c-6669-\n--\nkernel/events/core.c=12215=perf_event_set_addr_filter(struct perf_event event, char filter_str)\n--\nkernel/events/core.c-12253-\nkernel/events/core.c:12254:static int perf_event_set_filter(struct perf_event event, void __user *arg)\nkernel/events/core.c-12255-{\n" }
31/2	2026/10/20 00:31	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 31424 output: 36 thoughts: 15 Thoughts: Here's a summary of my thought process, as requested: Deconstructing `_perf_ioctl` and Its Locks Okay, so I'm diving into this `_perf_ioctl` function. My initial focus is on understanding what kind of locking mechanisms it's using. I need to figure out what specific lock or locks are being held within this function, because that's crucial for understanding its concurrency behavior and potential bottlenecks. This is probably related to performance counters, and I need to assess how safely they are being accessed by the IOCTL operations. I'm basically trying to construct a mental model of the critical sections and shared resources being protected. Understanding the lock type (mutex, spinlock, read-write lock, etc.) is the next step to evaluating any potential issues around contention, deadlock, or starvation. Knowing the lock is fundamental to understanding its function.
32/2	2026/10/20 00:31	tool	read-file	0m Args: { "File": "kernel/events/core.c", "FirstLine": 6615, "LineCount": 60 } Results: { "Contents": "6615:\tstatic long _perf_ioctl(struct perf_event event, unsigned int cmd, unsigned long arg)\n6616:\t{\n6617:\t\tvoid (func)(struct perf_event );\n6618:\t\tu32 flags = arg;\n6619:\t\n6620:\t\tif (event-\u003estate \u003c= PERF_EVENT_STATE_REVOKED)\n6621:\t\t\treturn -ENODEV;\n6622:\t\n6623:\t\tswitch (cmd) {\n6624:\t\tcase PERF_EVENT_IOC_ENABLE:\n6625:\t\t\tfunc = _perf_event_enable;\n6626:\t\t\tbreak;\n6627:\t\tcase PERF_EVENT_IOC_DISABLE:\n6628:\t\t\tfunc = _perf_event_disable;\n6629:\t\t\tbreak;\n6630:\t\tcase PERF_EVENT_IOC_RESET:\n6631:\t\t\tfunc = _perf_event_reset;\n6632:\t\t\tbreak;\n6633:\t\n6634:\t\tcase PERF_EVENT_IOC_REFRESH:\n6635:\t\t\treturn _perf_event_refresh(event, arg);\n6636:\t\n6637:\t\tcase PERF_EVENT_IOC_PERIOD:\n6638:\t\t{\n6639:\t\t\tu64 value;\n6640:\t\n6641:\t\t\tif (copy_from_user(\u0026value, (u64 __user )arg, sizeof(value)))\n6642:\t\t\t\treturn -EFAULT;\n6643:\t\n6644:\t\t\treturn _perf_event_period(event, value);\n6645:\t\t}\n6646:\t\tcase PERF_EVENT_IOC_ID:\n6647:\t\t{\n6648:\t\t\tu64 id = primary_event_id(event);\n6649:\t\n6650:\t\t\tif (copy_to_user((void __user )arg, \u0026id, sizeof(id)))\n6651:\t\t\t\treturn -EFAULT;\n6652:\t\t\treturn 0;\n6653:\t\t}\n6654:\t\n6655:\t\tcase PERF_EVENT_IOC_SET_OUTPUT:\n6656:\t\t{\n6657:\t\t\tCLASS(fd, output)(arg);\t // arg == -1 =\u003e empty\n6658:\t\t\tstruct perf_event output_event = NULL;\n6659:\t\t\tif (arg != -1) {\n6660:\t\t\t\tif (!is_perf_file(output))\n6661:\t\t\t\t\treturn -EBADF;\n6662:\t\t\t\toutput_event = fd_file(output)-\u003eprivate_data;\n6663:\t\t\t}\n6664:\t\t\treturn perf_event_set_output(event, output_event);\n6665:\t\t}\n6666:\t\n6667:\t\tcase PERF_EVENT_IOC_SET_FILTER:\n6668:\t\t\treturn perf_event_set_filter(event, (void __user )arg);\n6669:\t\n6670:\t\tcase PERF_EVENT_IOC_SET_BPF:\n6671:\t\t{\n6672:\t\t\tstruct bpf_prog prog;\n6673:\t\t\tint err;\n6674:\t\n" }
33/2	2026/10/20 00:31	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 32510 output: 32 thoughts: 13 Thoughts: Here's my analysis of the provided thought process, tailored for an expert audience: Analyzing the `_perf_ioctl` Caller Okay, so the immediate goal is to understand what code is calling `_perf_ioctl`. This is a pretty standard debugging step when dealing with performance instrumentation or kernel interactions. Given the function name, I'm already anticipating it's related to some form of performance monitoring, likely using the `perf` subsystem. Now, the next logical step would be to figure out where this system call is being invoked. I'll need to trace the call graph to see what's leading up to this point, probably utilizing a tool like `perf` itself, `systemtap`, `ftrace`, or good old `gdb`. I'm especially keen to see the arguments passed to this ioctl; those are gold when trying to diagnose issues or understand the intended behavior. Context is king, so understanding the caller's purpose will be crucial to grasping its interaction with the `perf` subsystem. Time to dig in and see what the code reveals!
34/2	2026/10/20 00:31	tool	grepper	0m Args: { "Expression": "_perf_ioctl", "PathPrefixes": [ "kernel/events/core.c" ] } Results: { "Output": "kernel/events/core.c=6611=static int __perf_event_set_bpf_prog(struct perf_event event,\n--\nkernel/events/core.c-6614-\nkernel/events/core.c:6615:static long _perf_ioctl(struct perf_event event, unsigned int cmd, unsigned long arg)\nkernel/events/core.c-6616-{\n--\nkernel/events/core.c=6727=static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)\n--\nkernel/events/core.c-6738-\tctx = perf_event_ctx_lock(event);\nkernel/events/core.c:6739:\tret = _perf_ioctl(event, cmd, arg);\nkernel/events/core.c-6740-\tperf_event_ctx_unlock(event, ctx);\n" }
35/2	2026/10/20 00:31	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 33013 output: 23 thoughts: 1479 Thoughts: Analyzing a Circular Locking Dependency and Our Patch Series Okay, so here's the situation as I see it. There's a potential circular locking dependency lurking in the kernel, and I need to figure out if we're somehow responsible. Let's break down the dependency chain: The core issue appears to be that `perf_ioctl` holds `ctx->mutex` (`perf_event_ctx_lock`) while calling `_perf_ioctl`. Within `_perf_ioctl`, `perf_event_set_filter` does a potentially faulting `strndup_user` operation, which can take `mm->mmap_lock` due to a page fault during user memory access. Thus `ctx->mutex` is held while `mmap_lock` can be taken. Specifically, `ctx->mutex` for a cpuctx is `&cpuctx_mutex`. Meanwhile, unrelated code paths in things like the network block device (nbd), elevator, or block layer, can be taking `cpu_hotplug_lock` through functions such as `elevator_switch`, `blk_mq_update_nr_hw_queues`, or `nbd_genl_reconnect_sock_cb`. During CPU hotplug, `cpuhp_invoke_callback` calls `perf_event_init_cpu` which takes `&cpuctx_mutex` (under `pmus_lock`, under `cpuhp_state-up`, under `cpu_hotplug_lock`). Also, `nbd_queue_rq` acquires `cmd->lock` and `nsock->tx_lock` while block queue operations / elevator lock etc. `blk_alloc_queue` allocates with `GFP_KERNEL`, which in turn, can acquire `fs_reclaim`. And in the thread triggering the warning, `setsockopt` -> `ip_mroute_setsockopt` -> `copy_from_sockptr` -> `_copy_from_user` triggers a page fault which calls `do_user_addr_fault`, which takes `mmap_lock` and goes on to `expand_downwards`, then `mas_preallocate`, which allocates with `GFP_KERNEL` and tries to acquire `fs_reclaim`. This leads to the following circular dependency: `fs_reclaim` -> ... -> `cpu_hotplug_lock` -> `cpuhp_state-up` -> `pmus_lock` -> `cpuctx_mutex` -> `mmap_lock`. This is a classic recipe for a deadlock! Now the crucial question: Did our recent patch series have anything to do with this potential disaster? Let's meticulously check every single change in the series. I'll need to go through each patch: 1. `kernel/bpf/log.c`: Functions related to BPF log attribute reporting and finalization. Doesn't seem relevant. 2. `kernel/bpf/syscall.c`: The `link_create` syscall, which calls various BPF-related functions like `bpf_log_attr_create_vlog`, `bpf_prog_get`, `bpf_prog_attach_check_attach_type`, `bpf_xdp_link_attach`, and `bpf_log_attr_finalize`. 3. `include/linux/bpf_verifier.h`: Declarations and a stub related to BPF logging. 4. `include/linux/netdevice.h`: Declaration for `bpf_xdp_link_attach`. 5. `include/trace/events/xdp.h`: Removed a tracepoint related to BPF XDP link attach failure. 6. `net/core/dev.c`: This is the most interesting one. The patch series added a `bpf_log` call with error messages in `bpf_xdp_link_attach`. Crucially, it added `bpf_log(log, "Invalid target_ifindex.\n");` and `if (extack._msg) bpf_log(log, "%s\n", extack._msg);` in `bpf_xdp_link_attach`. 7. `tools/...`: Selftests and libbpf changes; nothing low-level. Did any of these changes touch any of the key ingredients of the circular dependency? Specifically: * `perf_ioctl`? No. * `cpuctx_mutex`? No. * `fs_reclaim`? No. * `mmap_lock`? No. * `expand_downwards`? No. * `ip_mroute_setsockopt`? No.
36/2	2026/10/20 00:31	tool	grepper	0m Args: { "Expression": "upgrade_mmap_lock_carefully" } Results: { "Output": "arch/um/kernel/trap.c=39=static inline bool mmap_upgrade_trylock(struct mm_struct mm)\n--\narch/um/kernel/trap.c-51-\narch/um/kernel/trap.c:52:static inline bool upgrade_mmap_lock_carefully(struct mm_struct mm, bool is_user)\narch/um/kernel/trap.c-53-{\n--\narch/um/kernel/trap.c=81=um_lock_mm_and_find_vma(struct mm_struct mm,\n--\narch/um/kernel/trap.c-111-\tif (!mmap_upgrade_trylock(mm)) {\narch/um/kernel/trap.c:112:\t\tif (!upgrade_mmap_lock_carefully(mm, is_user))\narch/um/kernel/trap.c-113-\t\t\treturn NULL;\n--\nmm/mmap_lock.c=453=static inline bool mmap_upgrade_trylock(struct mm_struct mm)\n--\nmm/mmap_lock.c-465-\nmm/mmap_lock.c:466:static inline bool upgrade_mmap_lock_carefully(struct mm_struct mm, struct pt_regs regs)\nmm/mmap_lock.c-467-{\n--\nmm/mmap_lock.c=496=struct vm_area_struct lock_mm_and_find_vma(struct mm_struct mm,\n--\nmm/mmap_lock.c-526-\tif (!mmap_upgrade_trylock(mm)) {\nmm/mmap_lock.c:527:\t\tif (!upgrade_mmap_lock_carefully(mm, regs))\nmm/mmap_lock.c-528-\t\t\treturn NULL;\n" }
37/2	2026/10/20 00:31	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 35998 output: 39 thoughts: 38 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: Investigating Potential Perf Event Filter Issues Right, let's dive in. My initial hunch is that there might be some interaction, or perhaps a bug, related to the `perf_event_set_filter` function within the `kernel/events/core.c` file. Given my experience, the first thing I'd do is run a quick `git log` search specifically targeting commits around that function. I'm looking for anything that touches upon the filter setting logic. Anything that might introduce a regression, some unexpected behavior, or even a subtle edge case I haven't considered. I'd pay close attention to the commit messages and the diffs themselves, of course. I'd be trying to identify recent changes which might be relevant to the issue at hand. Anything that was a refactor of the filter API, maybe some performance optimizations there or even just some bug fixes.
38/2	2026/10/20 00:31	tool	git-blame	0m Args: { "End": 12265, "File": "kernel/events/core.c", "Start": 12250 } Results: { "Output": "6ce77bfd6cedb 12250) \n375637bc52495 12251) \treturn ret;\n375637bc52495 12252) }\n375637bc52495 12253) \nc796bbbe8dccd 12254) static int perf_event_set_filter(struct perf_event event, void __user arg)\nc796bbbe8dccd 12255) {\nc796bbbe8dccd 12256) \tint ret = -EINVAL;\ne12f03d7031a9 12257) \tchar filter_str;\nc796bbbe8dccd 12258) \nc796bbbe8dccd 12259) \tfilter_str = strndup_user(arg, PAGE_SIZE);\nc796bbbe8dccd 12260) \tif (IS_ERR(filter_str))\nc796bbbe8dccd 12261) \t\treturn PTR_ERR(filter_str);\nc796bbbe8dccd 12262) \ne12f03d7031a9 12263) #ifdef CONFIG_EVENT_TRACING\ne12f03d7031a9 12264) \tif (perf_event_is_tracing(event)) {\ne12f03d7031a9 12265) \t\tstruct perf_event_context ctx = event-\u003ectx;\n" }
39/2	2026/10/20 00:31	llm	finding-triage-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 36720 output: 370 thoughts: 769 Thoughts: Analyzing the Lockdep Warning: No Connection to BPF Patch Series Okay, so I've been presented with a lockdep warning and the task of determining if a recent BPF patch series introduced it. Let's break this down. First, this lockdep issue, the one we're seeing, looks like it's been around for quite some time, judging by the mention of `c796bbbe8dccd` from 2011 and its association with `perf_event_set_filter`. That particular line, specifically the `strndup_user` call within `perf_event_set_filter` while holding `perf_event_ctx_lock`, has been a potential point of contention for over a decade. Now, tracing the dependency chain, we've got: `#10` is `perf_ioctl` -> `strndup_user` -> `might_fault` -> `mmap_lock`. Then there's `#9` through `#1`, which are connected to `perf_event_init_cpu`, `cpuhp_thread_fun`, `nbd`, `blk_mq`, and `elevator`. And finally, `#0` which involves `ip_mroute_setsockopt` -> `copy_from_sockptr` -> page fault -> `expand_downwards` -> `mas_preallocate` -> `fs_reclaim`. This whole chain is a classic mix of subsystems. The point is, none of this immediately screams "BPF patch series." Let's double-check the patch series in question. It consists of six patches, specifically focused on BPF link creation logging. It's adding log buffer support to `BPF_LINK_CREATE` within `kernel/bpf/syscall.c` and `kernel/bpf/log.c`, passing `log` to `bpf_xdp_link_attach`, removing the `bpf_xdp_link_attach_failed` tracepoint, and some related libbpf and selftests changes. Okay, so the patch series is entirely about BPF link creation logging. It's adding features. Now, back to the crash report, we're seeing a lockdep warning: "WARNING: possible circular locking dependency detected" involving `fs_reclaim` and `mm->mmap_lock` (held under `ctx->mutex` / `cpuctx_mutex`). The stack traces clearly show calls: * `ip_mroute_setsockopt` -> `copy_from_sockptr` -> page fault -> `mas_alloc_nodes` -> `fs_reclaim` * `perf_ioctl` -> `perf_event_set_filter` -> `strndup_user` -> `mm->mmap_lock` (held while under `ctx->mutex` / `cpuctx_mutex`) * perf cpu hotplug callbacks (`perf_event_init_cpu`) * nbd driver (`nbd_genl_reconnect_sock_cb`, `nbd_queue_rq`) * block layer elevator and blk_mq allocations From this, it's pretty clear that there's no direct connection between the BPF patch series and the lockdep cycle. The warning was triggered during fuzzing and that it involves existing lock dependencies between components such as perf, cpu hotplug, nbd, block layer, and `mmap_lock`. It also points to `setsockopt`, a page fault, and `fs_reclaim`. This means that it is unrelated. Therefore, the conclusion is that the `Introduced` flag should be set to `false`. I'll call `set-results` with that conclusion and with this detailed reasoning.
40/2	2026/10/20 00:32	tool	set-results	0m Args: { "Introduced": false, "Reasoning": "The crash report details a lockdep warning regarding a possible circular locking dependency:\n`fs_reclaim --\u003e \u0026cpuctx_mutex --\u003e \u0026mm-\u003emmap_lock`.\n\nThe dependency chain involves:\n1. `perf_ioctl()` holding `perf_event_context` mutex (`\u0026cpuctx_mutex`) while invoking `perf_event_set_filter()`, which calls `strndup_user()`, establishing a dependency of `\u0026cpuctx_mutex --\u003e \u0026mm-\u003emmap_lock`.\n2. CPU hotplug and PMU registration paths linking `cpu_hotplug_lock`, `cpuhp_state-up`, `pmus_lock`, and `cpuctx_mutex`.\n3. Network Block Device (`nbd`) operations interacting with queue locks, elevator locks, and memory allocations.\n4. An `ip_mroute_setsockopt()` syscall page faulting during `copy_from_sockptr()`, prompting stack expansion via `expand_downwards()`, which allocates Maple Tree nodes under `\u0026mm-\u003emmap_lock` with `GFP_KERNEL` (`fs_reclaim`).\n\nThe tested patch series (\"bpf: Add syscall common attrs support for link_create\") only touches BPF link creation logging in `kernel/bpf/syscall.c`, `kernel/bpf/log.c`, `net/core/dev.c`, and user-space tooling/selftests. It does not touch perf, nbd, mmap_lock, page fault handling, or any of the locks involved in this lockdep warning. This is a pre-existing lock ordering issue triggered independently during fuzzing." } Results: { "Introduced": false, "Reasoning": "The crash report details a lockdep warning regarding a possible circular locking dependency:\n`fs_reclaim --\u003e \u0026cpuctx_mutex --\u003e \u0026mm-\u003emmap_lock`.\n\nThe dependency chain involves:\n1. `perf_ioctl()` holding `perf_event_context` mutex (`\u0026cpuctx_mutex`) while invoking `perf_event_set_filter()`, which calls `strndup_user()`, establishing a dependency of `\u0026cpuctx_mutex --\u003e \u0026mm-\u003emmap_lock`.\n2. CPU hotplug and PMU registration paths linking `cpu_hotplug_lock`, `cpuhp_state-up`, `pmus_lock`, and `cpuctx_mutex`.\n3. Network Block Device (`nbd`) operations interacting with queue locks, elevator locks, and memory allocations.\n4. An `ip_mroute_setsockopt()` syscall page faulting during `copy_from_sockptr()`, prompting stack expansion via `expand_downwards()`, which allocates Maple Tree nodes under `\u0026mm-\u003emmap_lock` with `GFP_KERNEL` (`fs_reclaim`).\n\nThe tested patch series (\"bpf: Add syscall common attrs support for link_create\") only touches BPF link creation logging in `kernel/bpf/syscall.c`, `kernel/bpf/log.c`, `net/core/dev.c`, and user-space tooling/selftests. It does not touch perf, nbd, mmap_lock, page fault handling, or any of the locks involved in this lockdep warning. This is a pre-existing lock ordering issue triggered independently during fuzzing." }

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)