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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e45d5d41c134 Linux 5.15.200
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=101da6e6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=9dd0027c6cbaeea1e13c
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/79bf32e4dfac/disk-e45d5d41.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/13e2c5c833d9/vmlinux-e45d5d41.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8af7798ac1cf/bzImage-e45d5d41.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9dd002...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-....: (1 GPs behind) idle=e61/1/0x4000000000000002 softirq=8228/8229 fqs=2100
(detected by 0, t=10505 jiffies, g=9873, q=642)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4517 Comm: syz.2.55 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:irqtime_account_delta kernel/sched/cputime.c:37 [inline]
RIP: 0010:irqtime_account_irq+0xe2/0x1b0 kernel/sched/cputime.c:-1
Code: 00 00 00 83 f8 08 49 bc 00 00 00 00 00 fc ff df 0f 83 af 00 00 00 4e 8d 34 f5 20 08 e3 8b 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 <74> 08 4c 89 f7 e8 f4 7b 69 00 49 8b 06 4e 8d b4 38 f0 76 02 00 4c
RSP: 0018:ffffc90000dd0968 EFLAGS: 00000046
RAX: 1ffffffff17c6105 RBX: ffff8880b9127780 RCX: 5afd572ade111a00
RDX: 1ffffffff1e1ce08 RSI: ffffffff8a79f720 RDI: ffffffff8a79f6e0
RBP: 0000000000000000 R08: ffffffff8f0e7048 R09: ffffffff8f0e7058
R10: ffffffff8f0e7050 R11: ffffffff8f0e7043 R12: dffffc0000000000
R13: 0000000000000212 R14: ffffffff8be30828 R15: 0000000000000020
FS: 00007f71a33a86c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f71a3366d58 CR3: 000000002a59b000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
account_hardirq_exit include/linux/vtime.h:159 [inline]
__irq_exit_rcu+0x99/0x230 kernel/softirq.c:656
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
sysvec_irq_work+0x4f/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 e2 f0 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:ffffc90000dd0b00 EFLAGS: 00000206
RAX: 5afd572ade111a00 RBX: 1ffff920001ba164 RCX: 5afd572ade111a00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f740
RBP: ffffc90000dd0bd8 R08: ffffffff901d2157 R09: 1ffffffff203a42a
R10: dffffc0000000000 R11: fffffbfff203a42b R12: ffffffff8c322f00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000002
__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+0x4eb/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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [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> 2f da 8c f7 65 8b 05 d0 e7 3c 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90002def140 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 5afd572ade111a00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: 0000000000000001
RBP: ffffc90002def1d0 R08: ffffffff901d2157 R09: 1ffffffff203a42a
R10: dffffc0000000000 R11: fffffbfff203a42b R12: dffffc0000000000
R13: ffffffff8c322f00 R14: ffffffff8c323360 R15: 1ffff920005bde28
rcu_report_unblock_qs_rnp kernel/rcu/tree.c:2275 [inline]
rcu_preempt_deferred_qs_irqrestore+0x9dd/0xc30 kernel/rcu/tree_plugin.h:552
rcu_read_unlock_special+0x3dd/0x4a0 kernel/rcu/tree_plugin.h:673
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:772 [inline]
netlink_deliver_tap+0x153/0x180 net/netlink/af_netlink.c:338
__netlink_sendskb net/netlink/af_netlink.c:1261 [inline]
netlink_dump+0x823/0xcf0 net/netlink/af_netlink.c:2294
__netlink_dump_start+0x523/0x700 net/netlink/af_netlink.c:2386
netlink_dump_start include/linux/netlink.h:258 [inline]
xsk_diag_handler_dump+0x197/0x230 net/xdp/xsk_diag.c:193
sock_diag_rcv_msg+0x164/0x3e0 net/core/sock_diag.c:-1
netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2507
sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276
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: 0033:0x7f71a514df79
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:00007f71a33a8028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f71a53c7fa0 RCX: 00007f71a514df79
RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000009
RBP: 00007f71a51e47e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f71a53c8038 R14: 00007f71a53c7fa0 R15: 00007ffdd0ede078
</TASK>


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