syzbot


INFO: rcu detected stall in schedule_timeout

Status: upstream: reported C repro on 2025/11/04 19:17
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+0f0e5c7e191f01eca401@syzkaller.appspotmail.com
First crash: 44d, last: 4d11h
Bug presence (1)
Date Name Commit Repro Result
2025/11/08 upstream (ToT) 0d7bee10beeb C [report] INFO: rcu detected stall in corrupted
Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in schedule_timeout (3) cgroups mm 1 11 2172d 2172d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in schedule_timeout (7) kernel 1 C error error 33 3d19h 405d 0/29 upstream: reported C repro on 2024/11/09 08:24
linux-6.1 INFO: rcu detected stall in schedule_timeout (2) origin:lts-only 1 C 2 26d 107d 0/3 upstream: reported C repro on 2025/09/02 23:57
upstream INFO: rcu detected stall in schedule_timeout (2) kernel 1 2 2172d 2172d 0/29 closed as invalid on 2020/01/08 05:23
upstream INFO: rcu detected stall in schedule_timeout (4) kernel 1 1 877d 877d 0/29 closed as invalid on 2023/09/01 06:44
linux-6.1 INFO: rcu detected stall in schedule_timeout 1 28 545d 610d 0/3 auto-obsoleted due to no activity on 2024/08/31 04:44
upstream INFO: rcu detected stall in schedule_timeout (5) kernel 1 2 782d 818d 0/29 auto-obsoleted due to no activity on 2024/01/26 16:31
upstream INFO: rcu detected stall in schedule_timeout cgroups mm 1 69 2207d 2208d 0/29 closed as invalid on 2019/12/04 14:14
upstream INFO: rcu detected stall in schedule_timeout (6) usb 1 C done 40 424d 581d 28/29 fixed on 2024/10/22 11:57
linux-5.15 INFO: rcu detected stall in schedule_timeout origin:upstream 1 C 12 10d 576d 0/3 upstream: reported C repro on 2024/05/22 14:45

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=8461, q=125 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294955643-4294945141), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g8461 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27088 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_timer_base+0x49/0x270 kernel/time/timer.c:995
Code: 34 24 49 c1 ee 03 48 89 d8 48 c1 e8 03 48 89 44 24 08 eb 07 e8 48 6a 10 00 f3 90 48 b8 00 00 00 00 00 fc ff df 41 0f b6 04 06 <84> c0 0f 85 3d 01 00 00 48 8b 04 24 44 8b 38 44 89 fe 81 e6 00 00
RSP: 0018:ffffc90000167a08 EFLAGS: 00000a06
RAX: 0000000000000000 RBX: ffffc90000167a58 RCX: ffff88801be58000
RDX: 0000000000000000 RSI: ffffc90000167a58 RDI: ffffc90000167ba0
RBP: 0000000000000000 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: dffffc0000000000
R13: 1ffff9200002cf58 R14: 1ffff9200002cf78 R15: 0000000000000000
 __try_to_del_timer_sync+0x55/0x280 kernel/time/timer.c:1414
 __timer_delete_sync+0x1ff/0x2c0 kernel/time/timer.c:1574
 timer_delete_sync kernel/time/timer.c:1629 [inline]
 del_timer_sync include/linux/timer.h:200 [inline]
 schedule_timeout+0x16a/0x280 kernel/time/timer.c:2169
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5806 Comm: syz-executor419 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__kasan_check_read+0x0/0x20 mm/kasan/shadow.c:31
Code: 41 5c 41 5d 41 5e 41 5f 5d c3 48 c7 c7 85 9a 78 8c 4c 89 e6 eb 0a 48 c7 c7 25 13 61 8c 48 89 de e8 f5 2a 7f 08 31 ed eb d4 cc <f3> 0f 1e fa 89 f6 48 8b 0c 24 31 d2 e9 df ea ff ff 66 2e 0f 1f 84
RSP: 0018:ffffc900044afee0 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 3f4746455e41eb00
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e4a2128
RBP: ffffc900044aff48 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: 0000000000000000
R13: 0000000000000000 R14: ffffc900044aff58 R15: 0000000000000027
FS:  00007fef3654a6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000007e163000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:504 [inline]
 cpu_online include/linux/cpumask.h:1082 [inline]
 trace_irq_disable+0x28/0xe0 include/trace/events/preemptirq.h:36
 local_irq_disable_exit_to_user+0x1d/0x20 include/linux/entry-common.h:191
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x12/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fef36591137
Code: 0b e9 68 fe ff ff 48 83 c4 18 48 8d 3d 02 a4 08 00 5b 5d 41 5c 41 5d 41 5e 41 5f e9 43 b9 fd ff 0f 1f 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00
RSP: 002b:00007fef36549b88 EFLAGS: 00000206 ORIG_RAX: 0000000000000027
RAX: 0000000000000004 RBX: 00007fef36549cf0 RCX: 00007fef36591137
RDX: 00007fef36549bc0 RSI: 00007fef36549cf0 RDI: 0000000000000021
RBP: 0000000000000000 R08: 00007fef3654a6c0 R09: 00007fef3654a6c0
R10: 0000000000000000 R11: 0000000000000206 R12: 00007fef366153ec
R13: 0000000000000016 R14: 00007ffc453f0010 R15: 00007ffc453f00f8
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/15 03:47 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in schedule_timeout
2025/12/14 11:34 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in schedule_timeout
2025/11/04 19:17 linux-6.6.y 0a805b6ea8cd 686bf657 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in schedule_timeout
2025/12/03 07:55 linux-6.6.y 4791134e4aeb d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in schedule_timeout
* Struck through repros no longer work on HEAD.