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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3330a8d33e08 Linux 5.15.201
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1649cb5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=6796d37ce796dfdebc40
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/805fe5d5059e/disk-3330a8d3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/27b51f6fcd64/vmlinux-3330a8d3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c9998071ec80/bzImage-3330a8d3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6796d3...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 1-....: (1475 ticks this GP) idle=ac5/1/0x4000000000000000 softirq=6770/6770 fqs=5233
(t=10502 jiffies g=7041 q=2207)
NMI backtrace for cpu 1
CPU: 1 PID: 4363 Comm: syz.1.29 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
<IRQ>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_dump_cpu_stacks+0x22f/0x380 kernel/rcu/tree_stall.h:349
print_cpu_stall+0x31d/0x5f0 kernel/rcu/tree_stall.h:633
check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x6ea/0x1120 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:2021
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4ad/0xb70 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__rq_qos_done_bio+0x7c/0xb0 block/blk-rq-qos.c:100
Code: 4d 85 ff 74 10 e8 24 1a a8 fd 4c 89 f7 48 89 de 41 ff d7 eb 05 e8 14 1a a8 fd 49 83 c6 18 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 <74> 08 4c 89 f7 e8 da 25 ed fd 4d 8b 36 4d 85 f6 74 07 e8 ed 19 a8
RSP: 0018:ffffc90000dd0c28 EFLAGS: 00000246
RAX: 1ffff11003da8b83 RBX: ffff8880227e5780 RCX: ffff888062720000
RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000006
RBP: 1ffff110044fcaf1 R08: ffffffff8d89dc2f R09: 1ffffffff1b13b85
R10: dffffc0000000000 R11: fffffbfff1b13b86 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88801ed45c18 R15: ffffffff83d370e0
rq_qos_done_bio block/blk-rq-qos.h:195 [inline]
bio_endio+0x24d/0x750 block/bio.c:1451
req_bio_endio block/blk-core.c:261 [inline]
blk_update_request+0x876/0x1200 block/blk-core.c:1441
scsi_end_request+0x84/0x980 drivers/scsi/scsi_lib.c:544
scsi_io_completion+0x173/0x480 drivers/scsi/scsi_lib.c:940
blk_complete_reqs block/blk-mq.c:588 [inline]
blk_done_softirq+0xfa/0x140 block/blk-mq.c:593
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 6c c1 67 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 16 2d 71 08 e8 21 e4 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:ffffc9000322f688 EFLAGS: 00000286
RAX: c9a715c355f9b100 RBX: ffff8880b913a340 RCX: c9a715c355f9b100
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800
RBP: 1ffff11017227613 R08: ffffffff901d31ef R09: 1ffffffff203a63d
R10: dffffc0000000000 R11: fffffbfff203a63e R12: 1ffff110172275c1
R13: dffffc0000000000 R14: ffff8880b913ae08 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
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571
preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6596
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
__raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:404 [inline]
fasync_insert_entry+0x1e1/0x260 fs/fcntl.c:948
fasync_add_entry fs/fcntl.c:971 [inline]
fasync_helper+0x4e/0xa0 fs/fcntl.c:989
perf_fasync+0x7e/0xa0 kernel/events/core.c:6636
ioctl_fioasync fs/ioctl.c:383 [inline]
do_vfs_ioctl+0x1161/0x1ef0 fs/ioctl.c:795
__do_sys_ioctl fs/ioctl.c:872 [inline]
__se_sys_ioctl+0x83/0x170 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: 0033:0x7fa036f35799
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:00007fa03518f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa0371aefa0 RCX: 00007fa036f35799
RDX: 00002000000016c0 RSI: 0000000000005452 RDI: 0000000000000005
RBP: 00007fa036fcbbd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa0371af038 R14: 00007fa0371aefa0 R15: 00007ffe33a38ea8
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup