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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0d8395707651 Merge tag 'soc-fixes-7.2-2' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=161b0e49580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=e4be8226f3f8fba277bd
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/1249c4607b97/disk-0d839570.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6335a3777938/vmlinux-0d839570.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2baccda01a16/bzImage-0d839570.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e4be82...@syzkaller.appspotmail.com

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

write to 0xffffffff893de120 of 4 bytes by task 6796 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
trace_event_enable_disable+0x20/0x30 kernel/trace/trace_events.c:901
trace_event_trigger_enable_disable+0x9d/0xb0 kernel/trace/trace_events_trigger.c:-1
enable_eprobe kernel/trace/trace_eprobe.c:588 [inline]
enable_trace_eprobe kernel/trace/trace_eprobe.c:666 [inline]
eprobe_register+0x5a3/0x7d0 kernel/trace/trace_eprobe.c:741
__ftrace_event_enable_disable+0x276/0x4b0 kernel/trace/trace_events.c:877
ftrace_event_enable_disable kernel/trace/trace_events.c:907 [inline]
event_enable_write+0x127/0x1c0 kernel/trace/trace_events.c:1929
vfs_write+0x252/0x990 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+0x27e1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff893de120 of 4 bytes by interrupt on cpu 0:
probe_sched_wakeup+0x41/0xa0 kernel/trace/trace_sched_switch.c:45
__traceiter_sched_wakeup+0x26/0x40 include/trace/events/sched.h:178
__do_trace_sched_wakeup include/trace/events/sched.h:178 [inline]
trace_sched_wakeup include/trace/events/sched.h:178 [inline]
ttwu_do_wakeup kernel/sched/core.c:3730 [inline]
ttwu_do_activate+0x201/0x230 kernel/sched/core.c:3827
ttwu_queue kernel/sched/core.c:4077 [inline]
try_to_wake_up+0x44a/0x6c0 kernel/sched/core.c:4415
hrtimer_wakeup+0x36/0x50 kernel/time/hrtimer.c:2293
__run_hrtimer kernel/time/hrtimer.c:2032 [inline]
__hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096
hrtimer_interrupt+0x257/0x810 kernel/time/hrtimer.c:2215
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
__sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674

value changed: 0x00000001 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6794 Comm: syz.4.795 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================
EXT4-fs (loop5): error count since last fsck: 1
EXT4-fs (loop5): initial error at time 1785971660: mb_free_blocks:2049: inode 11: block 198
EXT4-fs (loop5): last error at time 1785971660: mb_free_blocks:2049: inode 11: block 198


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