syzbot


KCSAN: data-race in clockevents_program_event / print_tickdevice (14)

Status: moderation: reported on 2026/04/25 15:58
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+00e5a73d76c701febd2a@syzkaller.appspotmail.com
First crash: 11d, last: 5d06h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
0d0e8281-9116-4168-a65f-f0ac7e466498 assessment-kcsan Benign: ✅ Confident: ✅ KCSAN: data-race in clockevents_program_event / print_tickdevice (14) 2026/04/25 15:58 2026/04/25 15:58 2026/04/25 16:17 9c2d0995bb06e7518555bd3b755e327c89b59823
Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (8) kernel 6 1 869d 869d 0/29 auto-obsoleted due to no activity on 2024/01/23 08:37
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (6) kernel 6 28 1055d 1347d 0/29 auto-obsoleted due to no activity on 2023/07/21 02:50
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (11) kernel 6 1 399d 399d 0/29 auto-obsoleted due to no activity on 2025/05/27 18:27
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (7) kernel 6 2 922d 923d 0/29 auto-obsoleted due to no activity on 2023/11/30 21:56
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (5) kernel 6 7 1394d 1420d 0/29 auto-closed as invalid on 2022/08/15 19:00
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (2) kernel 6 1 1755d 1755d 0/29 auto-closed as invalid on 2021/08/19 20:40
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (10) kernel 6 2 614d 620d 0/29 auto-obsoleted due to no activity on 2024/10/04 08:26
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (9) kernel 6 1 757d 757d 0/29 auto-obsoleted due to no activity on 2024/05/13 19:49
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (4) kernel 6 1 1544d 1544d 0/29 auto-closed as invalid on 2022/03/19 14:36
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice kernel 6 1 1839d 1835d 0/29 auto-closed as invalid on 2021/05/28 09:07
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (13) kernel 6 1 135d 135d 0/29 auto-obsoleted due to no activity on 2026/02/16 14:17
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (3) kernel 6 5 1645d 1676d 0/29 auto-closed as invalid on 2021/12/08 10:38
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (12) kernel 6 4 201d 303d 0/29 auto-obsoleted due to no activity on 2025/12/11 22:50

Sample crash report:
==================================================================
BUG: KCSAN: data-race in clockevents_program_event / print_tickdevice

write to 0xffff888237c17ba0 of 8 bytes by task 12245 on cpu 0:
 clockevents_program_event+0x46/0x340 kernel/time/clockevents.c:347
 tick_program_event+0x79/0xc0 kernel/time/tick-oneshot.c:48
 hrtimer_start_range_ns+0xc33/0x10a0 kernel/time/hrtimer.c:-1
 hrtimer_start_expires include/linux/hrtimer.h:234 [inline]
 hrtimer_restart include/linux/hrtimer.h:242 [inline]
 common_hrtimer_rearm+0x85/0x90 kernel/time/posix-timers.c:296
 __posixtimer_deliver_signal kernel/time/posix-timers.c:314 [inline]
 posixtimer_deliver_signal+0x11f/0x300 kernel/time/posix-timers.c:340
 dequeue_signal+0x2ce/0x3a0 kernel/signal.c:660
 get_signal+0x375/0xf20 kernel/signal.c:2917
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x232/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c17ba0 of 8 bytes by task 12255 on cpu 1:
 print_tickdevice+0x142/0x340 kernel/time/timer_list.c:204
 timer_list_show+0x6c/0x170 kernel/time/timer_list.c:296
 seq_read_iter+0x636/0x940 fs/seq_file.c:273
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x471/0x6c0 fs/splice.c:362
 do_splice_read fs/splice.c:980 [inline]
 splice_direct_to_actor+0x26e/0x670 fs/splice.c:1084
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x382/0x650 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64 fs/read_write.c:1419 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
 x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000003e3f8f5dc0 -> 0x0000003e3f802884

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12255 Comm: syz.9.2336 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/01 12:00 upstream 26fd6bff2c05 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in clockevents_program_event / print_tickdevice
2026/04/25 15:58 upstream 27d128c1cff6 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in clockevents_program_event / print_tickdevice
* Struck through repros no longer work on HEAD.