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: 6d00h, last: 6d00h
▶ ▼ 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 12d 12d 0/3 upstream: reported on 2026/08/02 22:47
linux-5.15 INFO: rcu detected stall in dev_ioctl (2) 1 5 140d 244d 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 2173d 2173d 0/1 auto-closed as invalid on 2020/12/30 14:33
linux-6.1 INFO: rcu detected stall in dev_ioctl 1 2 131d 131d 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 1811d 1811d 0/1 auto-closed as invalid on 2021/12/27 14:21
upstream INFO: rcu detected stall in dev_ioctl batman 1 18 1586d 2454d 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 1688d 1688d 0/1 auto-closed as invalid on 2022/04/29 15:27
linux-5.15 INFO: rcu detected stall in dev_ioctl (3) 1 2 19d 23d 0/3 upstream: reported on 2026/07/22 13:58
linux-6.1 BUG: soft lockup in dev_ioctl 1 6 231d 390d 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 621d 621d 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 355d 355d 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 586d 670d 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 288d 357d 0/29 auto-obsoleted due to no activity on 2026/02/07 12:10
upstream BUG: soft lockup in dev_ioctl batman 1 2 821d 887d 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 749d 839d 0/2 auto-obsoleted due to no activity on 2024/10/24 08:58

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=58649, q=123 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 9392 (4295002600-4294993208), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 9393 jiffies! g58649 f0x2 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:26504 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: 0 PID: 12617 Comm: syz.0.1888 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:unwind_next_frame+0x67c/0x2990 arch/x86/kernel/unwind_orc.c:-1
Code: 8c e8 18 cc 4b 00 4d 85 f6 74 10 41 83 fe 01 75 14 e8 48 c7 4b 00 e9 ba 1b 00 00 e8 3e c7 4b 00 e9 94 1b 00 00 e8 34 c7 4b 00 <48> 8b 54 24 08 eb 54 e8 28 c7 4b 00 eb 25 e8 21 c7 4b 00 4c 8b 2c
RSP: 0018:ffffc90000006ff8 EFLAGS: 00000246
RAX: ffffffff813baa4c RBX: ffffffff8f9570bc RCX: ffff88804e03da00
RDX: 0000000000000100 RSI: ffffffff8cfa05a0 RDI: 0000000000000002
RBP: ffffc90000007118 R08: ffff88804e03da00 R09: 0000000000000002
R10: 0000000000000001 R11: 0000000000000100 R12: ffffffff8f9570c1
R13: ffffc900000070c8 R14: 0000000000000002 R15: dffffc0000000000
FS:  00007f92f041b6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe6684b7c06 CR3: 0000000023b7b000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000200000000300
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 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_clone+0x1eb/0x370 net/core/skbuff.c:1912
 deliver_clone net/bridge/br_forward.c:125 [inline]
 br_flood+0x411/0x670 net/bridge/br_forward.c:246
 br_handle_frame_finish+0xf2d/0x15c0 net/bridge/br_input.c:215
 nf_hook_bridge_pre net/bridge/br_input.c:299 [inline]
 br_handle_frame+0x7f6/0x14d0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xf94/0x3ab0 net/core/dev.c:5540
 __netif_receive_skb_one_core net/core/dev.c:5644 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5760
 process_backlog+0x380/0x710 net/core/dev.c:6088
 __napi_poll+0xbb/0x460 net/core/dev.c:6650
 napi_poll net/core/dev.c:6717 [inline]
 net_rx_action+0x65f/0xcc0 net/core/dev.c:6853
 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:finish_task_switch+0x267/0x8f0 kernel/sched/core.c:5256
Code: 2f 09 85 c0 0f 84 30 01 00 00 48 85 db 0f 85 4f 01 00 00 0f 1f 44 00 00 4c 89 e7 e8 93 d0 38 09 e8 1e 19 30 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:ffffc90004dcf280 EFLAGS: 00000282
RAX: 73e7addc97b1c000 RBX: 0000000000000000 RCX: 73e7addc97b1c000
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: ffffffff8b1d0ca0
RBP: ffffc90004dcf2d0 R08: ffffffff911eb52f R09: 1ffffffff223d6a5
R10: dffffc0000000000 R11: fffffbfff223d6a6 R12: ffff88804e03da00
R13: 1ffff110171c79a9 R14: dffffc0000000000 R15: ffff8880b8e3cd48
 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
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x111/0x120 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __unfreeze_partials+0x190/0x210 mm/slub.c:2660
 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
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 ____ip_mc_inc_group+0x2b3/0xac0 net/ipv4/igmp.c:1456
 __ip_mc_inc_group net/ipv4/igmp.c:1491 [inline]
 ip_mc_inc_group net/ipv4/igmp.c:1497 [inline]
 ip_mc_up+0x125/0x300 net/ipv4/igmp.c:1796
 inetdev_event+0x104b/0x1610 net/ipv4/devinet.c:1611
 notifier_call_chain+0x18f/0x380 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2077 [inline]
 call_netdevice_notifiers net/core/dev.c:2091 [inline]
 __dev_notify_flags+0x1ab/0x310 net/core/dev.c:8762
 dev_change_flags+0xde/0x1a0 net/core/dev.c:8800
 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: 0033:0x7f92ef59e0d9
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:00007f92f041b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f92ef825fa0 RCX: 00007f92ef59e0d9
RDX: 0000200000000000 RSI: 0000000000008914 RDI: 0000000000000009
RBP: 00007f92ef635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f92ef826038 R14: 00007f92ef825fa0 R15: 00007ffe17378b68
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.