[syzbot] [perf?] KCSAN: data-race in __perf_event_overflow / __perf_event_set_bpf_prog

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Jan 26, 2026, 6:50:27 PM (5 hours ago) Jan 26
to ac...@kernel.org, adrian...@intel.com, alexander...@linux.intel.com, iro...@google.com, james...@linaro.org, jo...@kernel.org, linux-...@vger.kernel.org, linux-pe...@vger.kernel.org, mark.r...@arm.com, mi...@redhat.com, namh...@kernel.org, pet...@infradead.org, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 023777797472 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12540a44580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8e27f4588a0f2183
dashboard link: https://syzkaller.appspot.com/bug?extid=2a077cb788749964cf68
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7a5f13477745/disk-02377779.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/526049e9cfef/vmlinux-02377779.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1da969a6e6f0/bzImage-02377779.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2a077c...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __perf_event_overflow / __perf_event_set_bpf_prog

write to 0xffff88811b219168 of 8 bytes by task 13065 on cpu 0:
perf_event_set_bpf_handler kernel/events/core.c:10352 [inline]
__perf_event_set_bpf_prog+0x418/0x470 kernel/events/core.c:11303
_perf_ioctl kernel/events/core.c:6376 [inline]
perf_ioctl+0x92e/0x15d0 kernel/events/core.c:6436
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
x64_sys_call+0x14b0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b219168 of 8 bytes by interrupt on cpu 1:
__perf_event_overflow+0x252/0x920 kernel/events/core.c:10410
perf_swevent_hrtimer+0x28d/0x310 kernel/events/core.c:11865
__run_hrtimer kernel/time/hrtimer.c:1777 [inline]
__hrtimer_run_queues+0x20f/0x590 kernel/time/hrtimer.c:1841
hrtimer_interrupt+0x269/0x810 kernel/time/hrtimer.c:1903
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
__sysvec_apic_timer_interrupt+0x5f/0x1d0 arch/x86/kernel/apic/apic.c:1062
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1056
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
__tsan_read8+0x12/0x190 kernel/kcsan/core.c:1025
ma_dead_node lib/maple_tree.c:572 [inline]
mtree_range_walk lib/maple_tree.c:2580 [inline]
mas_state_walk+0x485/0x650 lib/maple_tree.c:3298
mt_find+0x11d/0x3b0 lib/maple_tree.c:6497
find_vma+0x6c/0xa0 mm/mmap.c:906
lock_mm_and_find_vma+0x5f/0x400 mm/mmap_lock.c:453
do_user_addr_fault+0x277/0x1050 arch/x86/mm/fault.c:1357
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
fault_in_readable+0xad/0x170 mm/gup.c:-1
fault_in_iov_iter_readable+0x129/0x210 lib/iov_iter.c:106
generic_perform_write+0x3ce/0x490 mm/filemap.c:4363
shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3490
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x5a6/0x9f0 fs/read_write.c:686
ksys_write+0xdc/0x1a0 fs/read_write.c:738
__do_sys_write fs/read_write.c:749 [inline]
__se_sys_write fs/read_write.c:746 [inline]
__x64_sys_write+0x40/0x50 fs/read_write.c:746
x64_sys_call+0x2847/0x3000 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffffc900032a7000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13062 Comm: syz.1.2487 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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