syzbot


KCSAN: data-race in print_cpu / tick_nohz_idle_enter (11)

Status: moderation: reported on 2025/07/28 19:50
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+1d852428b8cd11950088@syzkaller.appspotmail.com
First crash: 27d, last: 27d
Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (7) kernel 6 1 725d 725d 0/29 auto-obsoleted due to no activity on 2023/10/05 16:08
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (4) kernel 6 3 1110d 1119d 0/29 auto-closed as invalid on 2022/09/15 04:11
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (8) kernel 6 1 551d 551d 0/29 auto-obsoleted due to no activity on 2024/03/27 09:49
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (3) kernel 6 1 1158d 1158d 0/29 auto-closed as invalid on 2022/07/29 11:15
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (10) kernel 6 25 95d 470d 0/29 auto-obsoleted due to no activity on 2025/07/17 05:10
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (5) kernel 6 1 952d 952d 0/29 auto-obsoleted due to no activity on 2023/02/27 15:47
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (6) kernel 6 1 867d 867d 0/29 auto-obsoleted due to no activity on 2023/05/16 12:25
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter kernel 6 1 1432d 1432d 0/29 auto-closed as invalid on 2021/10/28 01:37
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (2) kernel 6 2 1363d 1387d 0/29 auto-closed as invalid on 2022/01/05 10:03
upstream KCSAN: data-race in print_cpu / tick_nohz_idle_enter (9) kernel 6 1 515d 515d 0/29 auto-obsoleted due to no activity on 2024/05/02 11:27

Sample crash report:
==================================================================
BUG: KCSAN: data-race in print_cpu / tick_nohz_idle_enter

write to 0xffff888237d1b830 of 8 bytes by task 0 on cpu 1:
 tick_nohz_start_idle kernel/time/tick-sched.c:748 [inline]
 tick_nohz_idle_enter+0x89/0xe0 kernel/time/tick-sched.c:1264
 do_idle+0x3d/0x240 kernel/sched/idle.c:271
 cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:423
 start_secondary+0x95/0xa0 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x147

read to 0xffff888237d1b830 of 8 bytes by task 22162 on cpu 0:
 print_cpu+0x502/0x680 kernel/time/timer_list.c:162
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:295
 seq_read_iter+0x319/0x940 fs/seq_file.c:230
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x3c4/0x5f0 fs/splice.c:363
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26f/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2bb0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000051694748e8 -> 0x0000005169479a28

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 22162 Comm: syz.8.5052 Not tainted 6.16.0-syzkaller-01056-gae388edd4a8f #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/29 15:57 upstream ae388edd4a8f c4a95487 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in print_cpu / tick_nohz_idle_enter
2025/07/28 19:49 upstream 038d61fd6422 6654ea9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in print_cpu / tick_nohz_idle_enter
* Struck through repros no longer work on HEAD.