INFO: rcu detected stall in dev_ioctl (2)

Status: upstream: reported on 2026/08/09 04:57
Reported-by: syzbot+76f7b803e7aae581645c@syzkaller.appspotmail.com
First crash: 48d, last: 23h10m
▶ ▼ Similar bugs (15)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in dev_ioctl (2) 1 1 54d 54d 0/3 upstream: reported on 2026/08/02 22:47
linux-5.15 INFO: rcu detected stall in dev_ioctl (2) 1 5 183d 287d 0/3 auto-obsoleted due to no activity on 2026/07/05 19:56
linux-4.19 INFO: rcu detected stall in dev_ioctl 1 1 2216d 2216d 0/1 auto-closed as invalid on 2020/12/30 14:33
linux-6.1 INFO: rcu detected stall in dev_ioctl 1 2 173d 174d 0/3 auto-obsoleted due to no activity on 2026/07/15 04:42
linux-4.19 INFO: rcu detected stall in dev_ioctl (2) 1 1 1854d 1854d 0/1 auto-closed as invalid on 2021/12/27 14:21
upstream INFO: rcu detected stall in dev_ioctl batman 1 18 1629d 2497d 0/29 auto-closed as invalid on 2022/08/09 13:29
linux-4.19 INFO: rcu detected stall in dev_ioctl (3) 1 1 1731d 1731d 0/1 auto-closed as invalid on 2022/04/29 15:27
linux-5.15 INFO: rcu detected stall in dev_ioctl (3) 1 6 22d 66d 0/3 upstream: reported on 2026/07/22 13:58
linux-6.1 BUG: soft lockup in dev_ioctl 1 6 274d 433d 0/3 auto-obsoleted due to no activity on 2026/04/05 06:22
linux-5.15 INFO: rcu detected stall in dev_ioctl 1 1 664d 664d 0/3 auto-obsoleted due to no activity on 2025/03/11 17:46
linux-6.6 INFO: rcu detected stall in dev_ioctl 1 1 398d 398d 0/2 auto-obsoleted due to no activity on 2025/12/02 20:33
upstream INFO: rcu detected stall in dev_ioctl (2) mm 1 3 629d 712d 0/29 auto-obsoleted due to no activity on 2025/04/05 21:09
upstream BUG: soft lockup in dev_ioctl (2) mm 1 6 331d 400d 0/29 auto-obsoleted due to no activity on 2026/02/07 12:10
upstream BUG: soft lockup in dev_ioctl batman 1 2 864d 929d 0/29 auto-obsoleted due to no activity on 2024/08/13 06:45
android-5-15 BUG: soft lockup in dev_ioctl 1 7 792d 882d 0/2 auto-obsoleted due to no activity on 2024/10/24 08:58

Sample crash report:
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5791/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=10365, q=331 ncpus=2)
task:udevd           state:R  running task     stack:27336 pid:5791  ppid:5141   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6868
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6892
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 unwind_next_frame+0x201c/0x2990 arch/x86/kernel/unwind_orc.c:672
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 save_stack+0x125/0x230 mm/page_owner.c:128
 __reset_page_owner+0x4e/0x190 mm/page_owner.c:149
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2505
 release_pages+0x208a/0x2300 mm/swap.c:1022
 tlb_batch_pages_flush mm/mmu_gather.c:99 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:294 [inline]
 tlb_flush_mmu+0x379/0x510 mm/mmu_gather.c:301
 tlb_finish_mmu+0xf4/0x220 mm/mmu_gather.c:425
 exit_mmap+0x428/0xb90 mm/mmap.c:3315
 __mmput+0x118/0x3a0 kernel/fork.c:1362
 exit_mm+0x23f/0x340 kernel/exit.c:576
 do_exit+0x909/0x2530 kernel/exit.c:877
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1032
 __do_sys_exit_group kernel/exit.c:1043 [inline]
 __se_sys_exit_group kernel/exit.c:1041 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1041
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdaa88f16c5
RSP: 002b:00007ffd89b56818 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000564beea541a0 RCX: 00007fdaa88f16c5
RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000
RBP: 0000564beea41910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd89b56860 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10518 jiffies! g10365 f0x0 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:27848 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 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:
CPU: 1 PID: 5866 Comm: syz.3.8 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:178 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x2e/0x60 kernel/kcov.c:212
Code: 48 8b 04 24 65 48 8b 0d a0 2c 7c 7e 65 8b 15 a1 2c 7c 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 24 16 00 00 00 <74> 2c 8b 91 00 16 00 00 83 fa 02 75 21 48 8b 91 08 16 00 00 48 8b
RSP: 0018:ffffc900001ef9c0 EFLAGS: 00000246
RAX: ffffffff813be049 RBX: ffffffff8f1d1025 RCX: ffff888029d7bc00
RDX: 0000000000000100 RSI: ffffc90004b1ff10 RDI: ffffc900001efae8
RBP: dffffc0000000000 R08: ffff888029d7bc00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc90004b1fee8
R13: ffffc900001efae8 R14: ffffffff8f1d1024 R15: ffffc900001efae8
FS:  00007f8677ce96c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdaa8f95e80 CR3: 000000005c380000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 deref_stack_reg+0x29/0x230 arch/x86/kernel/unwind_orc.c:402
 unwind_next_frame+0x1781/0x2990 arch/x86/kernel/unwind_orc.c:648
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x17e/0x2c0 mm/slub.c:3519
 skb_ext_maybe_cow net/core/skbuff.c:6699 [inline]
 skb_ext_add+0x1b3/0x8e0 net/core/skbuff.c:6773
 nf_bridge_unshare net/bridge/br_netfilter_hooks.c:165 [inline]
 br_nf_forward_ip+0xc6/0x10d0 net/bridge/br_netfilter_hooks.c:713
 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
 nf_hook_slow+0xbd/0x200 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:259 [inline]
 NF_HOOK+0x23e/0x3e0 include/linux/netfilter.h:302
 __br_forward+0x433/0x610 net/bridge/br_forward.c:115
 deliver_clone net/bridge/br_forward.c:131 [inline]
 maybe_deliver+0xb5/0x150 net/bridge/br_forward.c:191
 br_flood+0x317/0x670 net/bridge/br_forward.c:237
 br_handle_frame_finish+0xf2d/0x15c0 net/bridge/br_input.c:215
 br_nf_hook_thresh+0x3cd/0x4a0 net/bridge/br_netfilter_hooks.c:1188
 br_nf_pre_routing_finish_ipv6+0x9e5/0xd20 net/bridge/br_netfilter_ipv6.c:-1
 NF_HOOK include/linux/netfilter.h:304 [inline]
 br_nf_pre_routing_ipv6+0x34d/0x6a0 net/bridge/br_netfilter_ipv6.c:184
 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
 br_handle_frame+0x1240/0x14d0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xf94/0x3ac0 net/core/dev.c:5564
 __netif_receive_skb_one_core net/core/dev.c:5668 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5784
 process_backlog+0x380/0x710 net/core/dev.c:6112
 __napi_poll+0xbb/0x460 net/core/dev.c:6674
 napi_poll net/core/dev.c:6741 [inline]
 net_rx_action+0x65f/0xcc0 net/core/dev.c:6877
 handle_softirqs+0x27d/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:call_rcu+0x69b/0x900 kernel/rcu/tree.c:2837
Code: f7 84 24 a0 00 00 00 00 02 00 00 43 c6 44 25 04 f8 75 4f f7 44 24 58 00 02 00 00 74 01 fb 48 c7 84 24 80 00 00 00 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90004b1eca0 EFLAGS: 00000206
RAX: b473fe5e3a596500 RBX: ffff888017d31798 RCX: b473fe5e3a596500
RDX: dffffc0000000000 RSI: ffffffff8acacce0 RDI: ffffffff8b1d3ba0
RBP: ffffc90004b1edd0 R08: ffffffff911eb52f R09: 1ffffffff223d6a5
R10: dffffc0000000000 R11: fffffbfff223d6a6 R12: dffffc0000000000
R13: 1ffff92000963da4 R14: ffff8880b8f3d258 R15: 00000000000000a7
 context_switch kernel/sched/core.c:5385 [inline]
 __schedule+0x15b6/0x4660 kernel/sched/core.c:6701
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6868
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6892
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 unwind_next_frame+0x201c/0x2990 arch/x86/kernel/unwind_orc.c:672
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 save_stack+0x125/0x230 mm/page_owner.c:128
 __reset_page_owner+0x4e/0x190 mm/page_owner.c:149
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 __kmem_cache_alloc_node+0x194/0x250 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node+0xa6/0x240 mm/slab_common.c:1014
 kmalloc_node include/linux/slab.h:620 [inline]
 kvmalloc_node+0x70/0x180 mm/util.c:617
 kvmalloc include/linux/slab.h:738 [inline]
 kvmalloc_array include/linux/slab.h:756 [inline]
 __ptr_ring_init_queue_alloc include/linux/ptr_ring.h:471 [inline]
 ptr_ring_init include/linux/ptr_ring.h:489 [inline]
 skb_array_init include/linux/skb_array.h:182 [inline]
 pfifo_fast_init+0x363/0x6a0 net/sched/sch_generic.c:871
 qdisc_create_dflt+0x11e/0x430 net/sched/sch_generic.c:1021
 mq_init+0x2c7/0x660 net/sched/sch_mq.c:90
 qdisc_create_dflt+0x11e/0x430 net/sched/sch_generic.c:1021
 attach_default_qdiscs net/sched/sch_generic.c:1201 [inline]
 dev_activate+0x1e0/0x1160 net/sched/sch_generic.c:1255
 __dev_open+0x347/0x430 net/core/dev.c:1528
 __dev_change_flags+0x1e8/0x6a0 net/core/dev.c:8747
 dev_change_flags+0x7c/0x1a0 net/core/dev.c:8819
 dev_ioctl+0x7b4/0x1140 net/core/dev_ioctl.c:770
 sock_do_ioctl+0x239/0x310 net/socket.c:1234
 sock_ioctl+0x5be/0x7e0 net/socket.c:1341
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8676d9e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8677ce9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8677025fa0 RCX: 00007f8676d9e159
RDX: 0000200000000200 RSI: 0000000000008914 RDI: 000000000000000b
RBP: 00007f8676e3506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8677026038 R14: 00007f8677025fa0 R15: 00007ffe3a3edcb8
 </TASK>
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/25 23:09 linux-6.6.y 79643295eba1 f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in dev_ioctl
2026/08/09 04:56 linux-6.6.y 6436c12a2ced 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in dev_ioctl
* Struck through repros no longer work on HEAD.