INFO: rcu detected stall in worker_thread (3)

Status: upstream: reported on 2026/07/20 15:45
Reported-by: syzbot+f1afb0a2511aa87b036a@syzkaller.appspotmail.com
First crash: 51d, last: 23d
▶ ▼ Similar bugs (17)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in worker_thread (3) mm cgroups 1 1 2437d 2437d 0/29 closed as invalid on 2020/01/08 05:33
upstream INFO: rcu detected stall in worker_thread (4) mm cgroups 1 28 2437d 2437d 0/29 closed as invalid on 2020/01/09 08:13
linux-5.15 INFO: rcu detected stall in worker_thread 1 1 1077d 1077d 0/3 auto-obsoleted due to no activity on 2024/01/09 18:17
upstream INFO: rcu detected stall in worker_thread (8) kernel 1 1 1220d 1220d 0/29 auto-obsoleted due to no activity on 2023/08/07 05:14
upstream INFO: rcu detected stall in worker_thread (5) kernel 1 2 1561d 1598d 0/29 auto-closed as invalid on 2022/08/31 00:50
android-6-12 INFO: rcu detected stall in worker_thread 1 1 333d 333d 0/1 auto-obsoleted due to no activity on 2026/01/09 16:24
upstream INFO: rcu detected stall in worker_thread (9) prio:low netfilter 1 syz, C done 5928 1h22m 1068d 0/29 upstream: reported C repro on 2023/10/07 18:33
upstream INFO: rcu detected stall in worker_thread (2) cgroups mm 1 12 2437d 2437d 0/29 closed as invalid on 2020/01/08 05:23
upstream INFO: rcu detected stall in worker_thread mm cgroups 1 150 2472d 2473d 0/29 closed as invalid on 2019/12/04 14:14
linux-6.1 INFO: rcu detected stall in worker_thread 1 6 812d 843d 0/3 auto-obsoleted due to no activity on 2024/09/27 16:46
linux-6.6 INFO: rcu detected stall in worker_thread origin:lts-only 1 syz, C done 340 2d07h 449d 0/2 upstream: reported C repro on 2025/06/18 07:15
upstream INFO: rcu detected stall in worker_thread (6) kernel 1 1 1437d 1437d 0/29 auto-obsoleted due to no activity on 2023/01/12 15:50
linux-5.15 INFO: rcu detected stall in worker_thread (2) 1 4 816d 821d 0/3 auto-obsoleted due to no activity on 2024/09/24 04:34
upstream INFO: rcu detected stall in worker_thread (7) kernel 1 1 1330d 1330d 0/29 auto-obsoleted due to no activity on 2023/04/27 16:37
linux-6.1 INFO: rcu detected stall in worker_thread (2) 1 1 596d 596d 0/3 auto-obsoleted due to no activity on 2025/05/01 18:18
upstream INFO: task hung in crda_timeout_work (8) wireless prio:high 1 syz, C done error 784 2h27m 712d 0/29 upstream: reported C repro on 2024/09/27 16:53
android-5-15 BUG: soft lockup in worker_thread origin:lts 1 syz, C done 1 745d 745d 0/2 auto-obsoleted due to no activity on 2024/12/04 04:19

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=92bc/1/0x4000000000000000 softirq=40865/40865 fqs=2
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P12285/1:b..l
	(detected by 0, t=10502 jiffies, g=63973, q=165 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 53 Comm: kworker/1:1H Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue:  0x0 (kblockd)
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:84 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x92/0x290 mm/kasan/generic.c:189
Code: 49 83 ff 10 7f 29 4d 85 ff 0f 84 38 01 00 00 4c 89 cb 48 f7 d3 4c 01 f3 41 80 3b 00 0f 85 86 01 00 00 49 ff c3 48 ff c3 75 ee <e9> 18 01 00 00 44 89 dd 83 e5 07 0f 84 b5 00 00 00 41 80 3b 00 4d
RSP: 0018:ffffc900001e08b0 EFLAGS: 00000056
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff8164079e
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90b10248
RBP: ffffc900001e0b10 R08: ffffffff90b1024f R09: 1ffffffff2162049
R10: dffffc0000000000 R11: fffffbfff216204a R12: dffffc0000000001
R13: ffff88801da9c700 R14: 1ffffffff2162049 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000001b000 CR3: 0000000028e32000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:228 [inline]
 check_wait_context kernel/locking/lockdep.c:4753 [inline]
 __lock_acquire+0x92e/0x7c40 kernel/locking/lockdep.c:5013
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
 debug_object_deactivate+0x63/0x380 lib/debugobjects.c:810
 debug_hrtimer_deactivate kernel/time/hrtimer.c:453 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1719 [inline]
 __hrtimer_run_queues+0x2d8/0xc90 kernel/time/hrtimer.c:1815
 hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:finish_task_switch+0x267/0x8e0 kernel/sched/core.c:5125
Code: d6 08 85 c0 0f 84 38 01 00 00 48 85 db 0f 85 57 01 00 00 e9 e7 04 00 00 4c 89 e7 e8 93 b1 e0 08 e8 2e 11 2f 00 fb 4c 8b 65 b8 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc90000be7ba0 EFLAGS: 00000286
RAX: a5229ad280b29000 RBX: 0000000000000000 RCX: a5229ad280b29000
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: ffffffff8adf5de0
RBP: ffffc90000be7bf0 R08: ffff8880b8e3ad03 R09: 1ffff110171c75a0
R10: dffffc0000000000 R11: ffffed10171c75a1 R12: ffff88801da9bc00
R13: ffff8880b8f3ba48 R14: dffffc0000000000 R15: ffff8880b8f3b7d0
 context_switch kernel/sched/core.c:5249 [inline]
 __schedule+0x1087/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 worker_thread+0xf5a/0x12a0 kernel/workqueue.c:2460
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
task:syz.8.2046      state:R  running task     stack:26192 pid:12285 ppid:11239  flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6732
 preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6756
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 vprintk_emit+0x5e9/0x6a0 kernel/printk/printk.c:2304
 _printk+0xda/0x130 kernel/printk/printk.c:2328
 blk_print_req_error+0x175/0x210 block/blk-mq.c:798
 blk_update_request+0xb7e/0xdf0 block/blk-mq.c:911
 blk_mq_end_request block/blk-mq.c:1052 [inline]
 blk_mq_try_issue_directly+0x19b/0x1e0 block/blk-mq.c:2725
 blk_mq_submit_bio+0x135f/0x2100 block/blk-mq.c:3058
 __submit_bio+0x1a2/0x290 block/blk-core.c:591
 __submit_bio_noacct_mq block/blk-core.c:668 [inline]
 submit_bio_noacct_nocheck+0x79b/0xaa0 block/blk-core.c:697
 submit_bh fs/buffer.c:2707 [inline]
 __bread_slow fs/buffer.c:1177 [inline]
 __bread_gfp+0x1bb/0x330 fs/buffer.c:1370
 sb_bread include/linux/buffer_head.h:338 [inline]
 udf_tread fs/udf/misc.c:-1 [inline]
 udf_read_tagged+0x123/0xe50 fs/udf/misc.c:219
 udf_check_anchor_block+0x1e7/0x6a0 fs/udf/super.c:1889
 udf_scan_anchors+0x52c/0x640 fs/udf/super.c:1967
 udf_find_anchor fs/udf/super.c:1985 [inline]
 udf_load_vrs+0x1a1/0xb00 fs/udf/super.c:2050
 udf_fill_super+0x69e/0x1930 fs/udf/super.c:2228
 mount_bdev+0x28a/0x3c0 fs/super.c:1443
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:632
 vfs_get_tree+0x88/0x270 fs/super.c:1573
 do_new_mount+0x247/0xa40 fs/namespace.c:3078
 do_mount fs/namespace.c:3421 [inline]
 __do_sys_mount fs/namespace.c:3629 [inline]
 __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f958639e0d9
RSP: 002b:00007f95872a2028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f9586626090 RCX: 00007f958639e0d9
RDX: 00002000000001c0 RSI: 0000200000000100 RDI: 0000200000000400
RBP: 00007f9586435024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000008000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9586626128 R14: 00007f9586626090 R15: 00007ffdedd871c8
 </TASK>
rcu: rcu_preempt kthread starved for 10487 jiffies! g63973 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:26800 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1350 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 4573 Comm: kworker/u4:9 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:check_kcov_mode kernel/kcov.c:193 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:216
Code: 14 41 80 7e 65 8b 15 15 41 80 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 <83> fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc
RSP: 0018:ffffc900056377f8 EFLAGS: 00000246
RAX: ffffffff81773243 RBX: dffffc0000000000 RCX: ffff88802e111e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90005637960 R08: ffffffff90b10247 R09: 1ffffffff2162048
R10: dffffc0000000000 R11: fffffbfff2162049 R12: 1ffff110171e8219
R13: ffff8880b8e3bdc0 R14: 0000000000000001 R15: ffff8880b8f410c8
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7e123f643c CR3: 000000000c88e000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 csd_lock_wait kernel/smp.c:424 [inline]
 smp_call_function_many_cond+0x1163/0x1250 kernel/smp.c:998
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1165
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1574 [inline]
 text_poke_bp_batch+0x2b7/0x850 arch/x86/kernel/alternative.c:1774
 text_poke_flush arch/x86/kernel/alternative.c:1965 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1972
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:207
 static_key_enable+0x16/0x20 kernel/jump_label.c:220
 toggle_allocation_gate+0xba/0x470 mm/kfence/core.c:821
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/17 16:45 linux-6.1.y e4f7d8be268e 905244d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in worker_thread
2026/07/20 15:44 linux-6.1.y 090666d3cc90 de6a700d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in worker_thread
* Struck through repros no longer work on HEAD.