[v6.1] INFO: rcu detected stall in inet_diag_dump_compat

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 228da13e907e Linux 6.1.175
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=130a6156580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4dd3c1715f0a309b
dashboard link: https://syzkaller.appspot.com/bug?extid=e4f88e317b26fe8b03db
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/894d01ce6736/disk-228da13e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2a4cec18e217/vmlinux-228da13e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/32550387ebe8/bzImage-228da13e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e4f88e...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2641 jiffies s: 134965 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: 32398 Comm: syz.1.9093 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:lock_is_held_type+0x61/0x190 kernel/locking/lockdep.c:5701
Code: 0f 85 f4 00 00 00 65 48 8b 1d 3b 16 d3 75 83 bb dc 0a 00 00 00 0f 85 df 00 00 00 41 89 f7 49 89 fe 48 c7 04 24 00 00 00 00 9c <8f> 04 24 4c 8b 2c 24 fa 48 c7 c7 80 27 8c 8a e8 eb 12 00 00 65 ff
RSP: 0018:ffffc900001e0750 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff88801aa8da00 RCX: 6a0b76f8fb5f2c00
RDX: ffff88801aa8da00 RSI: 00000000ffffffff RDI: ffffffff8cb2de60
RBP: 00000000ffffffff R08: dffffc0000000000 R09: 1ffffffff215fe48
R10: dffffc0000000000 R11: fffffbfff215fe49 R12: ffffffff8cb805e0
R13: 1ffff9200003c100 R14: ffffffff8cb2de60 R15: 00000000ffffffff
FS: 00007f17da5f66c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f63cf577ff8 CR3: 000000001df42000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
bpf_prog_run_array include/linux/bpf.h:1658 [inline]
trace_call_bpf+0x1f2/0x6b0 kernel/trace/bpf_trace.c:135
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 82 30 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:ffffc900001e0ac0 EFLAGS: 00000206
RAX: 6a0b76f8fb5f2c00 RBX: 1ffff9200003c160 RCX: 6a0b76f8fb5f2c00
RDX: dffffc0000000000 RSI: ffffffff8a8c1aa0 RDI: ffffffff8adf2060
RBP: ffffc900001e0bb0 R08: ffffffff90aff2cf R09: 1ffffffff215fe59
R10: dffffc0000000000 R11: fffffbfff215fe5a R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3b900 R15: 0000000000000002
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
ieee80211_iterate_active_interfaces_atomic+0x156/0x170 net/mac80211/util.c:826
mac80211_hwsim_beacon+0xb7/0x1b0 drivers/net/wireless/mac80211_hwsim.c:2147
__run_hrtimer kernel/time/hrtimer.c:1751 [inline]
__hrtimer_run_queues+0x54a/0xd50 kernel/time/hrtimer.c:1815
hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1832
handle_softirqs+0x2a1/0x930 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:lock_acquire+0x225/0x4a0 kernel/locking/lockdep.c:5666
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90003536e60 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 6a0b76f8fb5f2c00
RDX: 0000000000000000 RSI: ffffffff8a8c2c20 RDI: ffffffff8adf2060
RBP: ffffc90003536f78 R08: dffffc0000000000 R09: 1ffffffff215fe59
R10: dffffc0000000000 R11: fffffbfff215fe5a R12: 0000000000000001
R13: 1ffff920006a6dd8 R14: 0000000000000246 R15: dffffc0000000000
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
inet_diag_dump_icsk+0x372/0x14c0 net/ipv4/inet_diag.c:1038
__inet_diag_dump+0x1f6/0x380 net/ipv4/inet_diag.c:1179
inet_diag_dump_compat+0x17e/0x220 net/ipv4/inet_diag.c:1288
netlink_dump+0x6a3/0xd00 net/netlink/af_netlink.c:2236
__netlink_dump_start+0x537/0x6f0 net/netlink/af_netlink.c:2338
netlink_dump_start include/linux/netlink.h:269 [inline]
inet_diag_rcv_msg_compat+0x207/0x420 net/ipv4/inet_diag.c:1323
sock_diag_rcv_msg+0x3cc/0x5f0 net/core/sock_diag.c:-1
netlink_rcv_skb+0x1fb/0x450 net/netlink/af_netlink.c:2511
sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:295
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x74d/0x8d0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1872
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
____sys_sendmsg+0x5be/0x970 net/socket.c:2518
___sys_sendmsg+0x2a2/0x360 net/socket.c:2572
__sys_sendmsg net/socket.c:2601 [inline]
__do_sys_sendmsg net/socket.c:2610 [inline]
__se_sys_sendmsg+0x1bb/0x2a0 net/socket.c:2608
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: 0033:0x7f17dc39ce59
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:00007f17da5f6028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f17dc615fa0 RCX: 00007f17dc39ce59
RDX: 0000000000044010 RSI: 0000200000000180 RDI: 000000000000000f
RBP: 00007f17dc432d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f17dc616038 R14: 00007f17dc615fa0 R15: 00007ffe3a20acb8
</TASK>


---
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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 79643295eba1 Linux 6.6.157
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=171a2e05580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7be9809cedd6b69c
dashboard link: https://syzkaller.appspot.com/bug?extid=19bcd60fd3a2f8830839
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/9a7f189efa44/disk-79643295.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ddfcd71a7c34/vmlinux-79643295.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b5e3bd89aa2/bzImage-79643295.xz

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

Reported-by: syzbot+19bcd6...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (10498 ticks this GP) idle=9dac/1/0x4000000000000000 softirq=22852/22853 fqs=5144
rcu: hardirqs softirqs csw/system
rcu: number: 538488 154 0
rcu: cputime: 6724 45752 755 ==> 52490(ms)
rcu: (t=10501 jiffies g=26081 q=1668 ncpus=2)
CPU: 0 PID: 8193 Comm: syz.0.516 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:55 [inline]
RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:393 [inline]
RIP: 0010:deref_stack_reg+0x39/0x230 arch/x86/kernel/unwind_orc.c:403
Code: 89 54 24 10 48 89 34 24 49 89 ff 48 bd 00 00 00 00 00 fc ff df e8 07 ab 4b 00 49 8d 7f 08 48 89 f8 48 c1 e8 03 48 89 44 24 08 <80> 3c 28 00 74 05 e8 0c 37 a4 00 4d 8b 77 08 49 8d 7f 10 49 89 fd
RSP: 0018:ffffc90000007448 EFLAGS: 00000a02
RAX: 1ffff92000000eae RBX: ffffffff8f8d1a47 RCX: ffff888027500000
RDX: 0000000000000100 RSI: ffffc90000007820 RDI: ffffc90000007570
RBP: dffffc0000000000 R08: ffff888027500000 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc900000077f0
R13: ffffc90000007568 R14: ffffffff8f8d1a46 R15: ffffc90000007568
FS: 00007f1f63eae6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f6eeb711d58 CR3: 000000002cd53000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
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
ref_tracker_alloc+0x1b8/0x4b0 lib/ref_tracker.c:209
__netdev_tracker_alloc include/linux/netdevice.h:4159 [inline]
netdev_hold include/linux/netdevice.h:4188 [inline]
dst_init+0xc0/0x470 net/core/dst.c:52
dst_alloc+0x12e/0x170 net/core/dst.c:94
ip6_dst_alloc net/ipv6/route.c:344 [inline]
icmp6_dst_alloc+0x7c/0x400 net/ipv6/route.c:3320
ndisc_send_skb+0x422/0x1480 net/ipv6/ndisc.c:493
addrconf_rs_timer+0x36b/0x640 net/ipv6/addrconf.c:4036
call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1752 [inline]
__run_timers+0x570/0x810 kernel/time/timer.c:2023
run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
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: 33 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 53 28 3d 09 e8 0e 23 30 00 fb 4c 8b 65 b8 <49> 8d bc 24 00 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc90003696c60 EFLAGS: 00000286
RAX: 95df3ffdba455200 RBX: 0000000000000000 RCX: 95df3ffdba455200
RDX: dffffc0000000000 RSI: ffffffff8acacce0 RDI: ffffffff8b1d3ba0
RBP: ffffc90003696cb0 R08: ffffffff911eb58f R09: 1ffffffff223d6b1
R10: dffffc0000000000 R11: fffffbfff223d6b2 R12: ffff888027500000
R13: 1ffff110171c79a1 R14: dffffc0000000000 R15: ffff8880b8e3cd08
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 include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:141 [inline]
mptcp_diag_dump+0xf46/0x1330 net/mptcp/mptcp_diag.c:197
__inet_diag_dump+0x1f6/0x380 net/ipv4/inet_diag.c:1179
inet_diag_dump_compat+0x182/0x230 net/ipv4/inet_diag.c:1288
netlink_dump+0x738/0xec0 net/netlink/af_netlink.c:2269
__netlink_dump_start+0x57c/0x7a0 net/netlink/af_netlink.c:2377
netlink_dump_start include/linux/netlink.h:338 [inline]
inet_diag_rcv_msg_compat+0x215/0x440 net/ipv4/inet_diag.c:1323
sock_diag_rcv_msg+0x3d3/0x5f0 net/core/sock_diag.c:-1
netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:298
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x61b/0x980 net/socket.c:2595
___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2687 [inline]
__se_sys_sendmsg+0x1d0/0x2c0 net/socket.c:2685
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: 0033:0x7f1f62f9e159

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:00007f1f63eae028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1f63225fa0 RCX: 00007f1f62f9e159
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 000000000000004f
RBP: 00007f1f6303506b R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007f1f63226038 R14: 00007f1f63225fa0 R15: 00007ffd04caa248