syzbot

 sign-in | mailing list | source | docs
🐞 Open [700]
🐞 Fixed [72]
🐞 Invalid [879]
⬇ Missing Backports [111]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in pwq_unbound_release_workfn (2)

Status: upstream: reported on 2025/05/28 17:46
Reported-by: syzbot+3779eaac5078e34be805@syzkaller.appspotmail.com
First crash: 2d17h, last: 2d17h
▶ ▼ Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in pwq_unbound_release_workfn kernel 1 1279d 1279d 0/28 closed as invalid on 2022/02/08 10:10
upstream INFO: rcu detected stall in pwq_unbound_release_workfn (2) kernel 1 1057d 1057d 0/28 auto-closed as invalid on 2022/09/06 17:05
linux-5.15 INFO: rcu detected stall in pwq_unbound_release_workfn 1 204d 204d 0/3 auto-obsoleted due to no activity on 2025/02/15 16:46
linux-6.1 INFO: rcu detected stall in pwq_unbound_release_workfn 1 294d 294d 0/3 auto-obsoleted due to no activity on 2024/11/17 13:02
upstream INFO: rcu detected stall in pwq_unbound_release_workfn (3) kernel 1 856d 856d 0/28 auto-obsoleted due to no activity on 2023/04/25 19:12
upstream INFO: rcu detected stall in pwq_unbound_release_workfn (4) kernel 2 690d 739d 0/28 auto-obsoleted due to no activity on 2023/10/08 15:59

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=4a5/1/0x4000000000000000 softirq=44495/44496 fqs=32 
	(detected by 0, t=10502 jiffies, g=60861, q=415)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7059 Comm: kworker/1:15 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events pwq_unbound_release_workfn
RIP: 0010:find_held_lock kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__lock_release kernel/locking/lockdep.c:5300 [inline]
RIP: 0010:lock_release+0x1fc/0x870 kernel/locking/lockdep.c:5643
Code: 89 4c 24 28 83 f9 32 0f 83 ca 04 00 00 4b 8d 04 b6 4c 8d 24 c3 48 89 c3 4c 89 e7 48 8b 74 24 08 e8 89 c9 44 08 44 89 7c 24 3c <44> 89 fa 85 c0 0f 84 d2 01 00 00 4d 85 e4 0f 84 0b 03 00 00 4d 8d
RSP: 0018:ffffc90000dd0b40 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 000000000000000f RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff96350c00 RDI: ffff88802776a928
RBP: ffffc90000dd0c50 R08: dffffc0000000000 R09: fffffbfff1ad1556
R10: fffffbfff1ad1556 R11: 1ffffffff1ad1555 R12: ffff88802776a928
R13: dffffc0000000000 R14: 0000000000000003 R15: 0000000000000003
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000006038 CR3: 000000007e03c000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:158 [inline]
 _raw_spin_unlock_irqrestore+0x6d/0x100 kernel/locking/spinlock.c:194
 debug_hrtimer_deactivate kernel/time/hrtimer.c:415 [inline]
 debug_deactivate+0x1d/0x1c0 kernel/time/hrtimer.c:471
 __run_hrtimer kernel/time/hrtimer.c:1658 [inline]
 __hrtimer_run_queues+0x2db/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lockdep_unregister_key+0x4ae/0x500 kernel/locking/lockdep.c:6334
Code: 48 3b 84 24 80 00 00 00 75 39 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 ee a1 44 08 41 f7 c4 00 02 00 00 74 8b fb 84 db <75> 8a eb 9b 0f 0b e9 58 ff ff ff 0f 0b e9 c4 fe ff ff 0f 0b e9 11
RSP: 0018:ffffc9000436fb20 EFLAGS: 00000246
RAX: f870370f2cca1600 RBX: 0000000000000000 RCX: f870370f2cca1600
RDX: 0000000000000001 RSI: ffffffff8a0b1fc0 RDI: ffffffff8a59a700
RBP: ffffc9000436fbf0 R08: dffffc0000000000 R09: fffffbfff1fedbc9
R10: fffffbfff1fedbc9 R11: 1ffffffff1fedbc8 R12: 0000000000000a07
R13: ffff88807b34a129 R14: ffffffff8ff6b028 R15: 1ffff9200086df68
 wq_unregister_lockdep kernel/workqueue.c:3518 [inline]
 pwq_unbound_release_workfn+0x262/0x2b0 kernel/workqueue.c:3756
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 10438 jiffies! g60861 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:28032 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 13244 Comm: syz.8.2858 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3932 [inline]
 rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1690 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0xb88/0xd70 kernel/smp.c:969
Code: b6 44 05 00 84 c0 0f 85 9d 00 00 00 41 8b 1c 24 89 de 83 e6 01 31 ff e8 a6 55 0b 00 83 e3 01 75 07 e8 3c 52 0b 00 eb 43 f3 90 <48> b8 00 00 00 00 00 fc ff df 41 0f b6 44 05 00 84 c0 75 11 41 f7
RSP: 0018:ffffc900041af1c0 EFLAGS: 00000246
RAX: ffffffff816c6f2b RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc9000f7bd000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc900041af300 R08: dffffc0000000000 R09: fffffbfff1ff3647
R10: fffffbfff1ff3647 R11: 1ffffffff1ff3646 R12: ffff8880b9140588
R13: 1ffff110172280b1 R14: ffff8880b903b380 R15: 0000000000000001
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1135
 kill_bdev block/bdev.c:76 [inline]
 set_blocksize+0x2eb/0x370 block/bdev.c:157
 sb_set_blocksize+0x45/0xe0 block/bdev.c:166
 ocfs2_get_sector+0x9b/0x4a0 fs/ocfs2/super.c:1757
 ocfs2_sb_probe fs/ocfs2/super.c:748 [inline]
 ocfs2_fill_super+0x3cd/0x4d80 fs/ocfs2/super.c:989
 mount_bdev+0x287/0x3c0 fs/super.c:1400
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3014
 do_mount fs/namespace.c:3357 [inline]
 __do_sys_mount fs/namespace.c:3565 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3542
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f5b9b84a10a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5b996afe68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5b996afef0 RCX: 00007f5b9b84a10a
RDX: 0000200000004440 RSI: 0000200000000040 RDI: 00007f5b996afeb0
RBP: 0000200000004440 R08: 00007f5b996afef0 R09: 00000000000008c0
R10: 00000000000008c0 R11: 0000000000000246 R12: 0000200000000040
R13: 00007f5b996afeb0 R14: 000000000000442b R15: 00002000000001c0
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/28 17:45 linux-5.15.y 98f47d0e9b8c 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in pwq_unbound_release_workfn
* Struck through repros no longer work on HEAD.