[v5.15] INFO: rcu detected stall in __netlink_dump_start

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ef251c45f1cd Linux 5.15.204
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1444aece580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=1857c78eaf0145df8022
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d1111b17150c/disk-ef251c45.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e8f68743cd64/vmlinux-ef251c45.xz
kernel image: https://storage.googleapis.com/syzbot-assets/04a632baddab/bzImage-ef251c45.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1857c7...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 GPs behind) idle=d81/1/0x4000000000000002 softirq=6498/6499 fqs=2100
(detected by 1, t=10506 jiffies, g=7193, q=1766)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4313 Comm: syz.1.12 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:irq_work_run_list+0xdf/0x340 kernel/irq_work.c:176
Code: 3c 28 00 74 08 48 89 df e8 1e 33 39 00 48 83 3b 00 0f 84 21 02 00 00 48 89 df be 08 00 00 00 e8 a7 34 39 00 45 31 f6 4c 87 33 <4d> 85 f6 0f 84 0c 02 00 00 4c 89 f0 48 c1 e8 03 42 80 3c 28 00 74
RSP: 0018:ffffc90000007940 EFLAGS: 00000046
RAX: 1ffff11017206701 RBX: ffff8880b9033d70 RCX: ffffffff81852059
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff8880b9033d70
RBP: ffffc900000079f8 R08: ffff8880b9033d77 R09: 1ffff110172067ae
R10: dffffc0000000000 R11: ffffed10172067af R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880b903b1f0 R15: 1ffff92000000f2c
FS: 00007fe23d7dd6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33119ff8 CR3: 00000000240b4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
irq_work_run+0x63/0xe0 kernel/irq_work.c:186
__sysvec_irq_work+0x98/0x240 arch/x86/kernel/irq_work.c:22
instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
sysvec_irq_work+0x4a/0xc0 arch/x86/kernel/irq_work.c:17
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
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 32 e1 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007b00 EFLAGS: 00000206
RAX: c1481da291a0fe00 RBX: 1ffff92000000f64 RCX: c1481da291a0fe00
RDX: dffffc0000000000 RSI: ffffffff8a2b2800 RDI: ffffffff8a79fe00
RBP: ffffc90000007bd8 R08: ffffffff901d50cf R09: 1ffffffff203aa19
R10: dffffc0000000000 R11: fffffbfff203aa1a R12: ffffffff8c323000
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:772 [inline]
ieee80211_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831
mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4f2/0xb70 kernel/time/hrtimer.c:1749
hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
handle_softirqs+0x339/0x830 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4804
Code: be ff ff ff ff e8 3c 52 68 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 e6 bd 71 08 e8 61 e6 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 c9 09 fe ff 43 80 3c
RSP: 0018:ffffc900031eefa8 EFLAGS: 00000282
RAX: c1481da291a0fe00 RBX: ffff8880b903a340 RCX: c1481da291a0fe00
RDX: dffffc0000000000 RSI: ffffffff8a2b2800 RDI: ffffffff8a79fe00
RBP: 1ffff11017207613 R08: ffffffff901d50cf R09: 1ffffffff203aa19
R10: dffffc0000000000 R11: fffffbfff203aa1a R12: 1ffff110172075c1
R13: dffffc0000000000 R14: ffff8880b903ae08 R15: 0000000000000000
finish_task_switch+0x12f/0x640 kernel/sched/core.c:4921
context_switch kernel/sched/core.c:5052 [inline]
__schedule+0x11f7/0x43c0 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
__mutex_lock_common+0xcfc/0x2400 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
__netlink_dump_start+0x11f/0x700 net/netlink/af_netlink.c:2352
netlink_dump_start include/linux/netlink.h:258 [inline]
rtnetlink_rcv_msg+0xdd9/0xf30 net/core/rtnetlink.c:5643
netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2507
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
__sys_sendmsg net/socket.c:2528 [inline]
__do_sys_sendmsg net/socket.c:2537 [inline]
__se_sys_sendmsg+0x1af/0x290 net/socket.c:2535
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fe23f583dd9
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:00007fe23d7dd028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe23f7fcfa0 RCX: 00007fe23f583dd9
RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000000000000006
RBP: 00007fe23f619d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe23f7fd038 R14: 00007fe23f7fcfa0 R15: 00007ffeb6079908
</TASK>


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