[v6.1] INFO: rcu detected stall in dev_ioctl (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fb28aa725e05 Linux 6.1.180
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1708bdb9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=2b4c5bcbbc71f74d6935
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6980f72dc28a/disk-fb28aa72.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b6cadb2b40be/vmlinux-fb28aa72.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cdec5b077b58/bzImage-fb28aa72.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2b4c5b...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2688 jiffies s: 4005 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4788 Comm: syz.0.109 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:202 [inline]
RIP: 0010:arch_atomic_fetch_or arch/x86/include/asm/atomic.h:242 [inline]
RIP: 0010:atomic_fetch_or include/linux/atomic/atomic-instrumented.h:407 [inline]
RIP: 0010:irq_work_claim kernel/irq_work.c:59 [inline]
RIP: 0010:irq_work_queue_on+0xd1/0x260 kernel/irq_work.c:137
Code: dd 44 00 4c 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 3e 01 00 00 45 8b 37 44 89 f1 83 c9 23 31 f6 44 89 f0 f0 41 0f b1 0f <41> 89 c4 41 0f 94 c5 40 0f 94 c6 bf 02 00 00 00 e8 da b0 f3 ff 45
RSP: 0018:ffffc900001e02c8 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff8880b8f3bbf0 RCX: 0000000000000023
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff8880b8f3bbf8
RBP: 0000000000000001 R08: ffff8880b8f3bbfb R09: 1ffff110171e777f
R10: dffffc0000000000 R11: ffffed10171e7780 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8880b8f3bbf8
FS: 00007fc27d7c96c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000cf3d CR3: 00000000298f0000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
rcu_read_unlock_special+0x3c9/0x510 kernel/rcu/tree_plugin.h:678
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
trace_call_bpf+0x5bb/0x6b0 kernel/trace/bpf_trace.c:137
perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10027
perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 a2 7c 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900001e0760 EFLAGS: 00000206
RAX: eb911fa7ad44f500 RBX: 1ffff9200003c0f4 RCX: eb911fa7ad44f500
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: ffffffff8adf5de0
RBP: ffffc900001e0860 R08: ffffffff90b10337 R09: 1ffffffff2162066
R10: dffffc0000000000 R11: fffffbfff2162067 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3bb00 R15: 0000000000000002
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
ndisc_send_skb+0xdc2/0x1520 net/ipv6/ndisc.c:521
addrconf_rs_timer+0x367/0x640 net/ipv6/addrconf.c:3986
call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1752 [inline]
__run_timers+0x56c/0x810 kernel/time/timer.c:2023
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x291/0x910 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 3f 89 1e f7 65 8b 05 b0 3a c8 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000c57f580 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: eb911fa7ad44f500
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: 0000000000000001
RBP: ffffc9000c57f600 R08: ffffffff90b10247 R09: 1ffffffff2162048
R10: dffffc0000000000 R11: fffffbfff2162049 R12: dffffc0000000000
R13: ffff8881436cce00 R14: ffffffff8cbebfa0 R15: 1ffff920018afeb0
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
pcpu_alloc+0xb47/0x16b0 mm/percpu.c:1850
qdisc_alloc+0x422/0xa40 net/sched/sch_generic.c:968
qdisc_create_dflt+0x5f/0x490 net/sched/sch_generic.c:1012
mq_init+0x2c3/0x650 net/sched/sch_mq.c:90
qdisc_create_dflt+0x11a/0x490 net/sched/sch_generic.c:1019
attach_default_qdiscs net/sched/sch_generic.c:1199 [inline]
dev_activate+0x1dc/0x1150 net/sched/sch_generic.c:1253
__dev_open+0x343/0x430 net/core/dev.c:1510
__dev_change_flags+0x1e4/0x6a0 net/core/dev.c:8676
dev_change_flags+0x78/0x1a0 net/core/dev.c:8748
dev_ifsioc+0x130/0xd50 net/core/dev_ioctl.c:326
dev_ioctl+0x55e/0xe80 net/core/dev_ioctl.c:572
sock_do_ioctl+0x245/0x320 net/socket.c:1216
sock_ioctl+0x48a/0x700 net/socket.c:1321
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
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: 0033:0x7fc27c99e019
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:00007fc27d7c9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc27cc25fa0 RCX: 00007fc27c99e019
RDX: 0000200000000080 RSI: 0000000000008914 RDI: 000000000000000d
RBP: 00007fc27ca3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc27cc26038 R14: 00007fc27cc25fa0 R15: 00007ffd2f7de3c8
</TASK>


---
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[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6436c12a2ced Linux 6.6.150
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1109e132580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f0bc3d90c30838b5
dashboard link: https://syzkaller.appspot.com/bug?extid=76f7b803e7aae581645c

compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:

disk image: https://storage.googleapis.com/syzbot-assets/2517715d4848/disk-6436c12a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5d2168057f18/vmlinux-6436c12a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/718cde8aaaf5/bzImage-6436c12a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+76f7b8...@syzkaller.appspotmail.com

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