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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cc5ec8769306 Linux 5.15.196
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10057c92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=aaef020d778c3c645489
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/ed7568bc5bb4/disk-cc5ec876.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e343e0aaac77/vmlinux-cc5ec876.xz
kernel image: https://storage.googleapis.com/syzbot-assets/089870f2a980/bzImage-cc5ec876.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aaef02...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (5 ticks this GP) idle=20b/1/0x4000000000000002 softirq=7901/7901 fqs=5245
(detected by 1, t=10502 jiffies, g=9249, q=1964)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4663 Comm: syz.0.105 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:memset+0x2d/0x40 mm/kasan/shadow.c:47
Code: 53 48 89 d3 89 f5 49 89 fe 48 8b 4c 24 18 48 89 d6 ba 01 00 00 00 e8 12 ef ff ff 84 c0 74 11 4c 89 f7 89 ee 48 89 da 5b 41 5e <5d> e9 1d e6 44 02 31 c0 5b 41 5e 5d c3 66 0f 1f 44 00 00 41 57 41
RSP: 0018:ffffc900000072b0 EFLAGS: 00000002
RAX: ffffffff8196e201 RBX: dffffc0000000000 RCX: ffffffff8196e274
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffc90000007340
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff52000000e88
R10: 0000000000000000 R11: 0000000000000020 R12: ffffe8ffffc7dbe8
R13: ffffe8ffffcbb000 R14: ffffc90000007340 R15: 0000000000000014
FS: 00007ffa289256c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbb2c3e7f98 CR3: 00000000297cc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
perf_tp_event+0xb4/0xb50 kernel/events/core.c:10030
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:ffffc900000077a0 EFLAGS: 00000206
RAX: 28b9fa6b4ab58700 RBX: 1ffff92000000ef8 RCX: 28b9fa6b4ab58700
RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: ffffffff8a59e580
RBP: ffffc90000007880 R08: dffffc0000000000 R09: fffffbfff1ff7c34
R10: fffffbfff1ff7c34 R11: 1ffffffff1ff7c33 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]
netif_receive_skb_list_internal+0x93a/0xb90 net/core/dev.c:5760
gro_normal_list net/core/dev.c:5913 [inline]
napi_complete_done+0x37d/0x830 net/core/dev.c:6651
virtqueue_napi_complete drivers/net/virtio_net.c:357 [inline]
virtnet_poll+0x912/0xef0 drivers/net/virtio_net.c:1624
__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
common_interrupt+0xb5/0xd0 arch/x86/kernel/irq.c:242
</IRQ>
<TASK>
asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:667
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
Code: 74 05 e8 de 0d cb f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> f6 95 9e f7 65 8b 05 87 93 4f 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000342f880 EFLAGS: 00000206
RAX: 28b9fa6b4ab58700 RBX: 0000000000000a02 RCX: 28b9fa6b4ab58700
RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: 0000000000000001
RBP: ffffc9000342f910 R08: dffffc0000000000 R09: fffffbfff1ff7c34
R10: fffffbfff1ff7c34 R11: 1ffffffff1ff7c33 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff888023a52cc0 R15: 1ffff92000685f10
finish_task_switch+0x267/0x640 kernel/sched/core.c:4952
context_switch kernel/sched/core.c:5052 [inline]
__schedule+0x11c3/0x4390 kernel/sched/core.c:6395
preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x13/0x60 kernel/kcov.c:206
Code: 48 8b 3d 50 d3 f1 0b 48 89 de 5b e9 57 9e 43 00 00 00 cc cc 00 00 cc 48 8b 04 24 65 48 8b 0d a4 a3 8a 7e 65 8b 15 a5 a3 8a 7e <81> e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 34 16 00 00
RSP: 0018:ffffc9000342fcd8 EFLAGS: 00000246
RAX: ffffffff81c65548 RBX: 0000000000000000 RCX: ffff88802ad35940
RDX: 0000000080000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000342fe50 R08: dffffc0000000000 R09: ffffc9000342fdb0
R10: fffff52000685fbb R11: 1ffff92000685fb6 R12: ffff888021ecb420
R13: 1ffff92000685fa4 R14: 1ffff110043d9690 R15: 0000000000000000
get_current_ioprio include/linux/ioprio.h:57 [inline]
init_sync_kiocb include/linux/fs.h:2341 [inline]
new_sync_write fs/read_write.c:503 [inline]
vfs_write+0x5e8/0xd00 fs/read_write.c:594
ksys_write+0x14d/0x250 fs/read_write.c:647
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: 0033:0x7ffa2a6bdfc9
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:00007ffa28925038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffa2a914fa0 RCX: 00007ffa2a6bdfc9
RDX: 000000000000000a RSI: 0000200000001640 RDI: 0000000000000007
RBP: 00007ffa2a740f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffa2a915038 R14: 00007ffa2a914fa0 R15: 00007ffe3d22fa48
</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