[moderation] [kernel?] KCSAN: data-race in __hrtimer_run_queues / hrtimer_try_to_cancel

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0e35b9b6ec0f Merge tag 'mm-hotfixes-stable-2026-07-06-17-4..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1208b832580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=0845bee7a0d7de883544
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [anna-...@linutronix.de fred...@kernel.org linux-...@vger.kernel.org tg...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/50ec388edb4b/disk-0e35b9b6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d5fde077ecdc/vmlinux-0e35b9b6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e0545f5d0fb1/bzImage-0e35b9b6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0845be...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __hrtimer_run_queues / hrtimer_try_to_cancel

write to 0xffff888237d1b7e0 of 8 bytes by interrupt on cpu 1:
__run_hrtimer kernel/time/hrtimer.c:2001 [inline]
__hrtimer_run_queues+0x11f/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+0x6f/0x80 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
__tsan_read8+0x0/0x190 kernel/kcsan/core.c:753
show_numa_info mm/vmalloc.c:5278 [inline]
vmalloc_info_show+0x503/0x850 mm/vmalloc.c:5363
traverse+0x12b/0x3b0 fs/seq_file.c:112
seq_read_iter+0x7dc/0x8f0 fs/seq_file.c:196
proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
do_iter_readv_writev+0x4f6/0x5a0 fs/read_write.c:-1
vfs_readv+0x1e8/0x6d0 fs/read_write.c:1019
do_preadv fs/read_write.c:1133 [inline]
__do_sys_preadv fs/read_write.c:1180 [inline]
__se_sys_preadv fs/read_write.c:1175 [inline]
__x64_sys_preadv+0xfd/0x1c0 fs/read_write.c:1175
x64_sys_call+0x2915/0x3020 arch/x86/include/generated/asm/syscalls_64.h:296
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 0xffff888237d1b7e0 of 8 bytes by task 3297 on cpu 0:
hrtimer_active kernel/time/hrtimer.c:1964 [inline]
hrtimer_try_to_cancel+0x7e/0x3c0 kernel/time/hrtimer.c:1623
hrtimer_cancel kernel/time/hrtimer.c:1750 [inline]
do_nanosleep+0xcd/0x360 kernel/time/hrtimer.c:2401
hrtimer_nanosleep+0xf2/0x290 kernel/time/hrtimer.c:2445
common_nsleep+0x62/0x80 kernel/time/posix-timers.c:1360
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1406 [inline]
__se_sys_clock_nanosleep+0x223/0x260 kernel/time/posix-timers.c:1383
__x64_sys_clock_nanosleep+0x55/0x70 kernel/time/posix-timers.c:1383
x64_sys_call+0x146e/0x3020 arch/x86/include/generated/asm/syscalls_64.h:231
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

value changed: 0x0000000000000000 -> 0xffff88811c780a30

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3297 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================


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