[moderation] [trace?] KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e8bf40d15402 Merge tag 'chrome-platform-firmware-v7.3' of ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12f4219e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=885647b8fd38e8cc
dashboard link: https://syzkaller.appspot.com/bug?extid=0f695b38e92691e0bd5f
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [linux-...@vger.kernel.org linux-tra...@vger.kernel.org mathieu....@efficios.com mhir...@kernel.org ros...@goodmis.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fc76692d0786/disk-e8bf40d1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bd9f315c1026/vmlinux-e8bf40d1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0b84b5a0a5a4/bzImage-e8bf40d1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0f695b...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch

write to 0xffffffff895d81a0 of 4 bytes by task 10568 on cpu 1:
tracing_start_sched_switch+0x8d/0x200 kernel/trace/trace_sched_switch.c:101
tracing_start_cmdline_record+0x13/0x20 kernel/trace/trace_sched_switch.c:135
__ftrace_event_enable_disable+0x203/0x4b0 kernel/trace/trace_events.c:867
ftrace_event_enable_disable kernel/trace/trace_events.c:907 [inline]
__ftrace_set_clr_event_nolock+0x3a1/0x820 kernel/trace/trace_events.c:1377
__ftrace_set_clr_event kernel/trace/trace_events.c:1410 [inline]
ftrace_set_clr_event+0x2a8/0x320 kernel/trace/trace_events.c:1460
ftrace_event_write+0x170/0x1d0 kernel/trace/trace_events.c:1548
vfs_write+0x254/0x9a0 fs/read_write.c:685
ksys_write+0xdc/0x1a0 fs/read_write.c:739
__do_sys_write fs/read_write.c:750 [inline]
__se_sys_write fs/read_write.c:747 [inline]
__x64_sys_write+0x40/0x50 fs/read_write.c:747
x64_sys_call+0x154e/0x2550 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff895d81a0 of 4 bytes by task 2980 on cpu 0:
probe_sched_switch+0x46/0xa0 kernel/trace/trace_sched_switch.c:32
__traceiter_sched_switch+0x3f/0x60 include/trace/events/sched.h:220
__do_trace_sched_switch include/trace/events/sched.h:220 [inline]
trace_sched_switch include/trace/events/sched.h:220 [inline]
__schedule+0xc31/0xd20 kernel/sched/core.c:7236
preempt_schedule_irq+0x2c/0x50 kernel/sched/core.c:7561
raw_irqentry_exit_cond_resched+0x49/0x60 kernel/entry/common.c:145
irqentry_exit_to_kernel_mode_preempt+0x2b/0x40 include/linux/irq-entry-common.h:468
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
irqentry_exit+0x7d/0x610 kernel/entry/common.c:167
sysvec_apic_timer_interrupt+0x44/0x80 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
__tsan_read4+0x12/0x190 kernel/kcsan/core.c:1024
avtab_search_node+0x49/0x2b0 security/selinux/ss/avtab.c:154
context_struct_compute_av+0x347/0xae0 security/selinux/ss/services.c:662
security_compute_av+0x360/0xa30 security/selinux/ss/services.c:1178
avc_compute_av+0x5d/0x420 security/selinux/avc.c:992
avc_perm_nonode+0x5e/0xe0 security/selinux/avc.c:1117
avc_has_perm_noaudit+0xea/0x120 security/selinux/avc.c:1160
selinux_inode_permission+0x4bc/0x740 security/selinux/hooks.c:3280
security_inode_permission+0x69/0xa0 security/security.c:1842
lookup_inode_permission_may_exec fs/namei.c:698 [inline]
may_lookup fs/namei.c:1961 [inline]
link_path_walk+0x1eb/0xdd0 fs/namei.c:2604
path_openat+0xe7/0x10d0 fs/namei.c:4996
do_file_open+0x16c/0x290 fs/namei.c:5029
do_sys_openat2+0xa0/0x130 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1434
x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000092f -> 0x00000930

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2980 Comm: udevd Tainted: G W syzkaller #0 PREEMPT(lazy)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================


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