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: 95d, last: 3d17h
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 792d 792d 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 1178d 1186d 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 619d 619d 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 1226d 1226d 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 163d 538d 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 1019d 1019d 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 935d 935d 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 1500d 1500d 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 1431d 1455d 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 583d 583d 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

read-write to 0xffff888237c1b7f8 of 8 bytes by task 0 on cpu 0:
 tick_sched_flag_set kernel/time/tick-sched.c:194 [inline]
 tick_nohz_idle_enter+0x59/0xe0 kernel/time/tick-sched.c:1263
 do_idle+0x3d/0x240 kernel/sched/idle.c:276
 cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:428
 rest_init+0xee/0xf0 init/main.c:757
 start_kernel+0x4dc/0x510 init/main.c:1111
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0xfc/0x100 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x147

read to 0xffff888237c1b7f8 of 8 bytes by task 30794 on cpu 1:
 print_cpu+0x3f8/0x660 kernel/time/timer_list.c:154
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:293
 seq_read_iter+0x636/0x950 fs/seq_file.c:272
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x442/0x660 fs/splice.c:363
 do_splice_read fs/splice.c:982 [inline]
 splice_direct_to_actor+0x26f/0x680 fs/splice.c:1086
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 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+0x2bb4/0x3000 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: 0x0000000000000030 -> 0x0000000000000035

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 30794 Comm: syz.1.8917 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/28 19:26 upstream fd57572253bc fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in print_cpu / tick_nohz_idle_enter
2025/10/21 11:08 upstream 6548d364a3e8 9832ed61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in print_cpu / tick_nohz_idle_enter
2025/10/21 11:00 upstream 6548d364a3e8 9832ed61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in print_cpu / tick_nohz_idle_enter
2025/09/16 06:28 upstream 46a51f4f5eda e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in print_cpu / tick_nohz_idle_enter
2025/08/31 00:56 upstream 11e7861d680c 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in print_cpu / tick_nohz_idle_enter
2025/07/29 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.