INFO: rcu detected stall in io_ring_exit_work (4)

Status: auto-obsoleted due to no activity on 2026/11/11 03:02
Subsystems: io-uring
Labels: prio:low
[Documentation on labels]
First crash: 126d, last: 91d
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ID Workflow Result Correct Bug Created Started Finished Revision
cd634098 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in io_ring_exit_work (4) 2026/07/11 00:04 2026/07/11 00:04 2026/07/11 01:02 23464ba0
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in io_ring_exit_work fs io-uring 1 syz, C error 6 1832d 1874d 0/29 auto-obsoleted due to no activity on 2023/04/16 14:02
upstream INFO: rcu detected stall in io_ring_exit_work (2) mm cgroups 1 1 836d 836d 0/29 auto-obsoleted due to no activity on 2024/10/27 16:22
upstream INFO: rcu detected stall in io_ring_exit_work (3) kernel prio:low 1 34 255d 302d 0/29 auto-obsoleted due to no activity on 2026/06/10 08:58

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P14725/1:b..l P14868/1:b..l P13/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=61937, q=2432 ncpus=1)
task:kworker/u8:1    state:R  running task     stack:23512 pid:13    tgid:13    ppid:2      task_flags:0x4208160 flags:0x00080000
Workqueue: iou_exit io_ring_exit_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556
 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline]
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x205/0xa00 kernel/entry/common.c:167
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_release+0x19e/0x310 kernel/locking/lockdep.c:5893
Code: ff 65 0f c1 05 a3 7b 7d 12 83 f8 01 0f 85 27 01 00 00 9c 58 f6 c4 02 0f 85 12 01 00 00 41 f7 c6 00 02 00 00 0f 85 c8 00 00 00 <48> 8b 44 24 10 65 48 2b 05 ad 34 7d 12 0f 85 4d 01 00 00 48 83 c4
RSP: 0018:ffffc90000127538 EFLAGS: 00000206
RAX: 0000000000000046 RBX: ffffffff8ebe8200 RCX: ffffc90000127544
RDX: 0000000000000003 RSI: ffffffff8e1835cb RDI: ffffffff8c400480
RBP: ffffffff81b876be R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000200 R11: 000000000000759b R12: ffff88801eac8000
R13: ffffc900001275f0 R14: 0000000000000202 R15: 0000000000000004
 rcu_lock_release include/linux/rcupdate.h:310 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1183 [inline]
 unwind_next_frame+0x3c3/0x2090 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2e5/0x6c0 mm/slub.c:5489
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 slab_free_hook mm/slub.c:2629 [inline]
 slab_free mm/slub.c:6377 [inline]
 kmem_cache_free+0x412/0x6b0 mm/slub.c:6504
 __io_req_caches_free+0x1a6/0x220 io_uring/io_uring.c:2148
 io_req_caches_free io_uring/io_uring.c:2160 [inline]
 io_ring_exit_work+0x42a/0xd7a io_uring/io_uring.c:2363
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
task:udevd           state:R  running task     stack:25104 pid:14868 tgid:14868 ppid:4963   task_flags:0x40014c flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556
 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline]
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x205/0xa00 kernel/entry/common.c:167
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:unwind_next_frame+0xd95/0x2090 arch/x86/kernel/unwind_orc.c:621
Code: 49 8d 7d 58 49 c7 45 50 00 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 63 0d 00 00 4c 89 c0 <49> c7 45 58 00 00 00 00 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03
RSP: 0018:ffffc900035774f0 EFLAGS: 00000246
RAX: ffffffff91d1d548 RBX: 0000000000000001 RCX: ffffffff91d1d544
RDX: 1ffff920006aeeb7 RSI: 1ffff920006aeeb5 RDI: ffffc900035775b8
RBP: ffffc900035775a8 R08: ffffffff91d1d548 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000016f0c R12: ffffc900035775b0
R13: ffffc90003577560 R14: ffffc90003577978 R15: ffffc90003577594
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
 __call_rcu_common.constprop.0+0xa5/0x9b0 kernel/rcu/tree.c:3159
 slab_free_hook mm/slub.c:2641 [inline]
 slab_free mm/slub.c:6377 [inline]
 kmem_cache_free+0x43e/0x6b0 mm/slub.c:6504
 anon_vma_free mm/rmap.c:137 [inline]
 __put_anon_vma+0x114/0x3a0 mm/rmap.c:2917
 put_anon_vma mm/internal.h:215 [inline]
 unlink_anon_vmas+0x5f3/0x8e0 mm/rmap.c:536
 free_pgtables+0x299/0xd80 mm/memory.c:401
 exit_mmap+0x44c/0xa00 mm/mmap.c:1312
 __mmput+0x12a/0x410 kernel/fork.c:1187
 mmput+0x67/0x80 kernel/fork.c:1210
 exit_mm kernel/exit.c:615 [inline]
 do_exit+0x8b1/0x2ae0 kernel/exit.c:997
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152
 __do_sys_exit_group kernel/exit.c:1163 [inline]
 __se_sys_exit_group kernel/exit.c:1161 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1161
 x64_sys_call+0x102c/0x1530 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feb766f16c5
RSP: 002b:00007ffff0748a28 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000055cab4f00210 RCX: 00007feb766f16c5
RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000
RBP: 000055cab4cb22c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffff0748a70 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
task:udevd           state:R  running task     stack:25848 pid:14725 tgid:14725 ppid:4963   task_flags:0x40014c flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556
 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline]
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x205/0xa00 kernel/entry/common.c:167
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:trace_lock_release include/trace/events/lock.h:68 [inline]
RIP: 0010:lock_release+0x40/0x310 kernel/locking/lockdep.c:5879
Code: 2d 3d 36 7d 12 48 89 6c 24 10 48 89 f5 0f 1f 44 00 00 65 8b 05 55 36 7d 12 83 f8 07 0f 87 07 02 00 00 48 0f a3 05 e0 89 3b 0f <0f> 82 02 02 00 00 44 8b 05 a7 bd 3b 0f 45 85 c0 0f 84 48 01 00 00
RSP: 0018:ffffc9000393f368 EFLAGS: 00000297
RAX: 0000000000000000 RBX: ffffffff8ebe8200 RCX: ffffffff91d10201
RDX: 0000000000000000 RSI: ffffffff81b876be RDI: ffffffff8ebe8200
RBP: ffffffff81b876be R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000016353 R12: ffffc9000393f470
R13: ffffc9000393f420 R14: ffffc9000393fb10 R15: ffffc9000393f454
 rcu_lock_release include/linux/rcupdate.h:310 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1183 [inline]
 unwind_next_frame+0x3c3/0x2090 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 save_stack+0x162/0x1e0 mm/page_owner.c:165
 __reset_page_owner+0x84/0x190 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 free_unref_folios+0xa44/0x1710 mm/page_alloc.c:3011
 folios_put_refs+0x585/0xaa0 mm/swap.c:1057
 free_pages_and_swap_cache+0x22d/0x3b0 mm/swap_state.c:586
 __tlb_batch_free_encoded_pages+0xe9/0x280 mm/mmu_gather.c:138
 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:417 [inline]
 tlb_flush_mmu mm/mmu_gather.c:424 [inline]
 tlb_finish_mmu+0x1b0/0x810 mm/mmu_gather.c:549
 exit_mmap+0x454/0xa00 mm/mmap.c:1313
 __mmput+0x12a/0x410 kernel/fork.c:1187
 mmput+0x67/0x80 kernel/fork.c:1210
 exit_mm kernel/exit.c:615 [inline]
 do_exit+0x8b1/0x2ae0 kernel/exit.c:997
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152
 __do_sys_exit_group kernel/exit.c:1163 [inline]
 __se_sys_exit_group kernel/exit.c:1161 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1161
 x64_sys_call+0x102c/0x1530 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feb766f16c5
RSP: 002b:00007ffff0748a28 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000055cab4f082a0 RCX: 00007feb766f16c5
RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000
RBP: 000055cab4cb22c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffff0748a70 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 217 jiffies! g61937 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:27528 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2123
 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2325
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 3215 Comm: kworker/R-bat_e Tainted: G             L      syzkaller #0 PREEMPT(lazy) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: bat_events batadv_tt_purge
RIP: 0010:deref_stack_reg arch/x86/kernel/unwind_orc.c:422 [inline]
RIP: 0010:unwind_next_frame+0x1579/0x2090 arch/x86/kernel/unwind_orc.c:677
Code: ff ff 84 c0 0f 84 f3 ed ff ff 48 89 ef e8 9f e2 ff ff 49 8d 7d 40 48 89 fa 48 89 c5 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 84 17 fa ff ff e8 a8 7a c2 00 e9 0d fa ff ff 48 b8
RSP: 0018:ffffc90000007170 EFLAGS: 00000a06
RAX: dffffc0000000000 RBX: 0000000000000002 RCX: ffffffff92644dea
RDX: 1ffff92000000e44 RSI: ffffc90000007bb0 RDI: ffffc90000007220
RBP: ffff888182c48500 R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000200 R11: 00000000000963e7 R12: ffffc90000007230
R13: ffffc900000071e0 R14: ffffc90000007bd8 R15: ffffc90000007214
FS:  0000000000000000(0000) GS:ffff888123dec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555723154e8 CR3: 00000000262b0000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2677 [inline]
 slab_free mm/slub.c:6377 [inline]
 kmem_cache_free+0x127/0x6b0 mm/slub.c:6504
 kfree_skbmem+0x19a/0x210 net/core/skbuff.c:1145
 __kfree_skb net/core/skbuff.c:1212 [inline]
 consume_skb net/core/skbuff.c:1445 [inline]
 consume_skb+0xd1/0x110 net/core/skbuff.c:1439
 nft_synproxy_eval_v6 net/netfilter/nft_synproxy.c:91 [inline]
 nft_synproxy_do_eval+0x919/0xce0 net/netfilter/nft_synproxy.c:145
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x2e5/0x19d0 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0xf3/0x400 net/netfilter/nft_chain_filter.c:162
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xbf/0x220 net/netfilter/core.c:619
 nf_hook.constprop.0+0x2a6/0x750 include/linux/netfilter.h:273
 NF_HOOK include/linux/netfilter.h:316 [inline]
 ip6_input+0xe0/0x2f0 net/ipv6/ip6_input.c:545
 dst_input include/net/dst.h:480 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:119 [inline]
 NF_HOOK include/linux/netfilter.h:318 [inline]
 NF_HOOK include/linux/netfilter.h:312 [inline]
 ipv6_rcv+0x263/0x3d0 net/ipv6/ip6_input.c:351
 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:6212
 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6325
 process_backlog+0x37a/0x1580 net/core/dev.c:6676
 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7735
 napi_poll net/core/dev.c:7798 [inline]
 net_rx_action+0xa40/0xf20 net/core/dev.c:7955
 handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622
 do_softirq kernel/softirq.c:523 [inline]
 do_softirq+0xac/0xe0 kernel/softirq.c:510
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 batadv_tt_local_purge+0x21c/0x3d0 net/batman-adv/translation-table.c:1366
 batadv_tt_purge+0x8b/0xbd0 net/batman-adv/translation-table.c:3565
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 rescuer_thread+0x905/0x14a0 kernel/workqueue.c:3629
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/13 02:56 upstream 3d6d817622b0 67796a05 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in io_ring_exit_work
2026/07/09 20:55 upstream 2c7c88a412aa 4167ee25 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in io_ring_exit_work
* Struck through repros no longer work on HEAD.