syzbot


KCSAN: data-race in hrtimer_reprogram / print_cpu (14)

Status: moderation: reported on 2025/08/20 21:15
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+3aa321f3515b213afed0@syzkaller.appspotmail.com
First crash: 154d, last: 21d
Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (11) kernel 6 6 571d 590d 0/29 auto-obsoleted due to no activity on 2024/08/04 04:55
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (9) kernel 6 7 682d 737d 0/29 auto-obsoleted due to no activity on 2024/04/14 23:48
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (13) kernel 6 1 300d 300d 0/29 auto-obsoleted due to no activity on 2025/05/23 00:02
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (6) kernel 6 19 914d 1100d 0/29 auto-obsoleted due to no activity on 2023/08/26 13:01
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (12) kernel 6 5 364d 443d 0/29 auto-obsoleted due to no activity on 2025/03/19 14:48
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu kernel 6 1 2133d 2133d 0/29 auto-closed as invalid on 2020/05/29 16:43
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (2) kernel 6 1 1967d 1967d 0/29 auto-closed as invalid on 2020/10/08 05:09
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (5) kernel 6 11 1193d 1277d 0/29 auto-obsoleted due to no activity on 2022/11/20 13:25
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (3) kernel 6 1 1536d 1536d 0/29 auto-closed as invalid on 2021/12/12 15:07
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (10) kernel 6 2 634d 636d 0/29 auto-obsoleted due to no activity on 2024/06/01 18:17
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (7) kernel 6 3 869d 879d 0/29 auto-obsoleted due to no activity on 2023/10/11 12:54
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (4) kernel 6 1 1500d 1500d 0/29 auto-closed as invalid on 2022/01/17 18:45
upstream KCSAN: data-race in hrtimer_reprogram / print_cpu (8) kernel 6 1 792d 772d 0/29 auto-obsoleted due to no activity on 2023/12/26 20:48

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

write to 0xffff888237c1b860 of 8 bytes by task 13318 on cpu 0:
 __hrtimer_reprogram kernel/time/hrtimer.c:656 [inline]
 hrtimer_reprogram+0x1a5/0x220 kernel/time/hrtimer.c:861
 hrtimer_start_range_ns+0x6b1/0x740 kernel/time/hrtimer.c:1323
 hrtimer_start_expires include/linux/hrtimer.h:273 [inline]
 hrtimer_sleeper_start_expires kernel/time/hrtimer.c:2039 [inline]
 do_nanosleep+0x79/0x330 kernel/time/hrtimer.c:2113
 hrtimer_nanosleep+0x1b8/0x360 kernel/time/hrtimer.c:2163
 common_nsleep+0x62/0x80 kernel/time/posix-timers.c:1352
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1398 [inline]
 __se_sys_clock_nanosleep+0x21a/0x250 kernel/time/posix-timers.c:1375
 __x64_sys_clock_nanosleep+0x55/0x70 kernel/time/posix-timers.c:1375
 x64_sys_call+0x2734/0x3000 arch/x86/include/generated/asm/syscalls_64.h:231
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c1b860 of 8 bytes by task 13325 on cpu 1:
 print_cpu+0x2ea/0x660 kernel/time/timer_list.c:131
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:293
 seq_read_iter+0x31e/0x950 fs/seq_file.c:230
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 do_iter_readv_writev+0x4a1/0x540 fs/read_write.c:-1
 vfs_readv+0x1ea/0x690 fs/read_write.c:1018
 do_preadv fs/read_write.c:1132 [inline]
 __do_sys_preadv fs/read_write.c:1179 [inline]
 __se_sys_preadv fs/read_write.c:1174 [inline]
 __x64_sys_preadv+0xfd/0x1c0 fs/read_write.c:1174
 x64_sys_call+0x2805/0x3000 arch/x86/include/generated/asm/syscalls_64.h:296
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000002f4fa9f000 -> 0x0000002f4f4890e5

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13325 Comm: syz.7.3207 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/31 16:43 upstream c8ebd433459b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in hrtimer_reprogram / print_cpu
2025/11/09 12:50 upstream 7bb4d6512545 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in hrtimer_reprogram / print_cpu
2025/10/24 00:06 upstream 266ee584e55e c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in hrtimer_reprogram / print_cpu
2025/10/23 08:43 upstream 43e9ad0c55a3 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in hrtimer_reprogram / print_cpu
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 hrtimer_reprogram / print_cpu
2025/10/12 15:04 upstream 67029a49db6c ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in hrtimer_reprogram / print_cpu
2025/09/09 10:31 upstream f777d1112ee5 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in hrtimer_reprogram / print_cpu
2025/09/05 02:50 upstream 08b06c30a445 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in hrtimer_reprogram / print_cpu
2025/08/20 21:14 upstream b19a97d57c15 0b9605c8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in hrtimer_reprogram / print_cpu
* Struck through repros no longer work on HEAD.