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INFO: rcu detected stall in sys_wait4 (7)

Status: auto-obsoleted due to no activity on 2026/06/05 10:44
Subsystems: fs
Labels: prio:low
[Documentation on labels]
First crash: 175d, last: 95d
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
64ee60a6-d478-4d27-974d-7bd71679bc71 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in sys_wait4 (7) 2026/05/15 06:21 2026/05/15 06:21 2026/05/15 06:36 6ccb967e465e832a7bfd7a116ad00d52a0923a5d
eff06247-7edd-4e4a-9c35-258afe80774c repro ❓ INFO: rcu detected stall in sys_wait4 (7) 2026/03/07 05:18 2026/03/07 05:18 2026/03/07 05:28 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_wait4 (3) kernel 1 1 1019d 1019d 0/29 auto-obsoleted due to no activity on 2023/11/24 01:26
upstream INFO: rcu detected stall in sys_wait4 (2) kernel 1 1 1528d 1528d 0/29 auto-closed as invalid on 2022/07/03 11:21
upstream INFO: rcu detected stall in sys_wait4 (4) mm 1 C done done 2 756d 789d 26/29 fixed on 2024/07/12 01:55
upstream INFO: rcu detected stall in sys_wait4 kernel 1 1 2159d 2159d 0/29 auto-closed as invalid on 2020/10/10 08:00
linux-5.15 INFO: rcu detected stall in sys_wait4 1 1 727d 727d 0/3 auto-obsoleted due to no activity on 2024/09/21 03:35
upstream INFO: rcu detected stall in sys_wait4 (5) kernel 1 1 530d 530d 0/29 auto-obsoleted due to no activity on 2025/03/26 13:51
linux-6.1 INFO: rcu detected stall in sys_wait4 1 1 1155d 1155d 0/3 auto-obsoleted due to no activity on 2023/08/09 13:38
upstream INFO: rcu detected stall in sys_wait4 (6) fs 1 2 338d 411d 0/29 auto-obsoleted due to no activity on 2025/10/04 12:51
linux-5.15 INFO: rcu detected stall in sys_wait4 (2) 1 1 41d 41d 0/3 upstream: reported on 2026/04/29 19:33

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P16/4:b..l P7723/1:b..l P29/4:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=21377, q=225 ncpus=2)
task:ktimers/1       state:R  running task     stack:23104 pid:29    tgid:29    ppid:2      task_flags:0x4208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x145f/0x5070 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule_rtlock+0x30/0x70 kernel/sched/core.c:7024
 rtlock_slowlock_locked+0x3819/0x4010 kernel/locking/rtmutex.c:1868
 rtlock_slowlock kernel/locking/rtmutex.c:1895 [inline]
 rtlock_lock kernel/locking/spinlock_rt.c:43 [inline]
 __rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline]
 rt_spin_lock+0x158/0x3e0 kernel/locking/spinlock_rt.c:57
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 kcov_remote_start+0x12d/0x710 kernel/kcov.c:886
 kcov_remote_start_common include/linux/kcov.h:50 [inline]
 ieee80211_rx_list+0x763/0x2fd0 net/mac80211/rx.c:5521
 ieee80211_rx_napi+0x1a8/0x3d0 net/mac80211/rx.c:5562
 ieee80211_rx include/net/mac80211.h:5216 [inline]
 ieee80211_handle_queued_frames+0xe8/0x1e0 net/mac80211/main.c:452
 tasklet_action_common+0x2bf/0x540 kernel/softirq.c:925
 handle_softirqs+0x1df/0x650 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 run_ktimerd+0x69/0x100 kernel/softirq.c:1138
 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
task:syz-executor    state:S stack:21592 pid:7723  tgid:7723  ppid:7707   task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x145f/0x5070 kernel/sched/core.c:6863
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7190
 irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:unwind_next_frame+0xd34/0x23d0 arch/x86/include/asm/stacktrace.h:-1
Code: 89 dd 49 c1 ed 03 48 b8 00 00 00 00 00 fc ff df 41 80 7c 05 00 00 74 08 48 89 df e8 d6 f6 ad 00 48 89 5c 24 60 4c 89 64 24 18 <49> 8d 5c 24 f8 4d 8b 66 10 48 b8 00 00 00 00 00 fc ff df 48 8b 4c
RSP: 0018:ffffc9001c577198 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: ffffc9001c577278 RCX: ffffffff8ef2409c
RDX: ffffffff8f68677a RSI: 0000000000000002 RDI: ffffffff8b3f5780
RBP: 1ffff920038aee4e R08: 0000000000000001 R09: ffffffff8d5ae940
R10: ffffc9001c5772b8 R11: ffffffff81ab9860 R12: ffffc9001c577b78
R13: 1ffff920038aee4f R14: ffffc9001c577268 R15: ffffc9001c570000
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3119 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3239
 destroy_inode fs/inode.c:401 [inline]
 evict+0x931/0xae0 fs/inode.c:861
 proc_invalidate_siblings_dcache+0x42c/0x6c0 fs/proc/inode.c:152
 release_task+0x11d4/0x16d0 kernel/exit.c:291
 wait_task_zombie kernel/exit.c:1274 [inline]
 wait_consider_task+0x1944/0x2e10 kernel/exit.c:1501
 do_wait_thread kernel/exit.c:1564 [inline]
 __do_wait+0x156/0x740 kernel/exit.c:1682
 do_wait+0x1e8/0x4f0 kernel/exit.c:1716
 kernel_wait4+0x1af/0x280 kernel/exit.c:1875
 __do_sys_wait4 kernel/exit.c:1903 [inline]
 __se_sys_wait4 kernel/exit.c:1899 [inline]
 __x64_sys_wait4+0x133/0x1e0 kernel/exit.c:1899
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd5cbe35897
RSP: 002b:00007fffb5923920 EFLAGS: 00000293 ORIG_RAX: 000000000000003d
RAX: ffffffffffffffda RBX: 000000000000003a RCX: 00007fd5cbe35897
RDX: 0000000040000001 RSI: 00007fffb592398c RDI: 00000000ffffffff
RBP: 00007fffb592398c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000001388

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/27 14:18 upstream c53f467229a7 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in sys_wait4
2025/12/24 19:33 upstream b927546677c8 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in sys_wait4
2025/12/17 01:37 upstream 40fbbd64bba6 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in sys_wait4
2026/03/07 10:42 net 55f854dd5bdd 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in sys_wait4
* Struck through repros no longer work on HEAD.