[v5.15] INFO: rcu detected stall in dev_ioctl (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 68efe5a6c16a Linux 5.15.197
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11439e1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7e6ed99963d6ee1d
dashboard link: https://syzkaller.appspot.com/bug?extid=500341fa036814fb4ce0
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/998e4247f9d0/disk-68efe5a6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4ef4066c91ec/vmlinux-68efe5a6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/922e7b640c48/bzImage-68efe5a6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+500341...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 ticks this GP) idle=d97/1/0x4000000000000002 softirq=33908/33908 fqs=2150
(detected by 1, t=10504 jiffies, g=46001, q=637)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 13922 Comm: syz.4.2551 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:perf_swevent_event+0x5/0x530 kernel/events/core.c:9606
Code: d9 80 e1 07 80 c1 03 38 c1 0f 8c 58 ff ff ff 48 89 df e8 9e 47 25 00 e9 4b ff ff ff e8 34 fa 0a 08 0f 1f 40 00 55 41 57 41 56 <41> 55 41 54 53 48 83 ec 20 48 89 cd 49 89 d6 49 89 f4 49 89 ff e8
RSP: 0018:ffffc90000007520 EFLAGS: 00000046
RAX: ffffffff8196e4d2 RBX: 1ffff11017206a4a RCX: ffff8880b90351c8
RDX: ffffc900000075c0 RSI: 0000000000000001 RDI: ffff888060ecd988
RBP: ffffc900000077a8 R08: dffffc0000000000 R09: fffffbfff1ad26b6
R10: fffffbfff1ad26b6 R11: 1ffffffff1ad26b5 R12: ffff8880b9035250
R13: ffff888060ecd988 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f53a846f6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c34818e CR3: 0000000029708000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
perf_tp_event+0x32c/0xb50 kernel/events/core.c:10047
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
perf_trace_preemptirq_template+0x2be/0x380 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x84/0x480 kernel/rcu/tree_plugin.h:674
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 ed 11 9e 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc90000007a00 EFLAGS: 00000206
RAX: 13bfb1ec5baabd00 RBX: 1ffff92000000f44 RCX: 13bfb1ec5baabd00
RDX: dffffc0000000000 RSI: ffffffff8a0b1be0 RDI: ffffffff8a59e800
RBP: ffffc90000007ae0 R08: dffffc0000000000 R09: fffffbfff1ff541a
R10: fffffbfff1ff541a R11: 1ffffffff1ff5419 R12: ffffffff8c120c00
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]
process_backlog+0x3e3/0x780 net/core/dev.c:6517
__napi_poll+0xc0/0x430 net/core/dev.c:7075
napi_poll net/core/dev.c:7142 [inline]
net_rx_action+0x4a8/0x9c0 net/core/dev.c:7232
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 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 ec 75 4e 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 96 da 57 08 e8 11 76 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 d9 0f fe ff 43 80 3c
RSP: 0018:ffffc9000315f928 EFLAGS: 00000286
RAX: 13bfb1ec5baabd00 RBX: ffff8880b903a340 RCX: 13bfb1ec5baabd00
RDX: dffffc0000000000 RSI: ffffffff8a0b1be0 RDI: ffffffff8a59e800
RBP: 1ffff11017207613 R08: dffffc0000000000 R09: fffffbfff1ff541a
R10: fffffbfff1ff541a R11: 1ffffffff1ff5419 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+0x11c3/0x4390 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+0xc71/0x2390 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
dev_ioctl+0x5e8/0xe50 net/core/dev_ioctl.c:611
sock_ioctl+0x67b/0x6e0 net/socket.c:1194
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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: 0033:0x7f53aa208749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f53a846f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f53aa45efa0 RCX: 00007f53aa208749
RDX: 0000200000000080 RSI: 00000000000089f0 RDI: 000000000000000a
RBP: 00007f53aa28cf91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f53aa45f038 R14: 00007f53aa45efa0 R15: 00007ffd263e38b8
</TASK>


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