[v6.1] INFO: rcu detected stall in sys_sendfile64

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bf4ad6fa4e53 Linux 6.1.28
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11596711280000
kernel config: https://syzkaller.appspot.com/x/.config?x=26fca33e75c97e43
dashboard link: https://syzkaller.appspot.com/bug?extid=0b49a99afa55f74c666e
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/058ee41df9de/disk-bf4ad6fa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/480706160d27/vmlinux-bf4ad6fa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e6a9f4f20a23/bzImage-bf4ad6fa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0b49a9...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-...D } 2656 jiffies s: 30897 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10615 Comm: syz-executor.0 Not tainted 6.1.28-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:228 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:240 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:444 [inline]
RIP: 0010:cpu_online include/linux/cpumask.h:1030 [inline]
RIP: 0010:trace_hrtimer_start include/trace/events/timer.h:198 [inline]
RIP: 0010:debug_activate kernel/time/hrtimer.c:476 [inline]
RIP: 0010:enqueue_hrtimer+0x90/0x390 kernel/time/hrtimer.c:1084
Code: 10 00 39 eb 0f 86 0a 01 00 00 e8 6b 68 10 00 89 ed 48 89 e8 48 c1 e8 06 48 8d 3c c5 e8 f6 52 8e be 08 00 00 00 e8 d0 ae 66 00 <31> db 48 0f a3 2d 6e 8f d9 0c 40 0f 92 c5 0f 92 c3 bf 02 00 00 00
RSP: 0018:ffffc90000007d28 EFLAGS: 00000056
RAX: 0000000000000001 RBX: 0000000000000002 RCX: ffffffff81796770
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e52f6e8
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff1ca5ede
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: ffff8880b982a6c0 R14: ffff88807e270340 R15: dffffc0000000000
FS: 00007fb80ef60700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002000a038 CR3: 0000000020c4e000 CR4: 00000000003506f0
Call Trace:
<IRQ>
__run_hrtimer kernel/time/hrtimer.c:1702 [inline]
__hrtimer_run_queues+0x728/0xe50 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1095 [inline]
__sysvec_apic_timer_interrupt+0x156/0x580 arch/x86/kernel/apic/apic.c:1112
sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1106
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194
Code: 9c 8f 44 24 20 42 80 3c 23 00 74 08 4c 89 f7 e8 a2 89 54 f7 f6 44 24 21 02 75 4e 41 f7 c7 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 67 68 d2 f6 65 8b 05 18 e4 76 75 85 c0 74 3f 48 c7 04 24 0e 36
RSP: 0018:ffffc9001d07f000 EFLAGS: 00000206
RAX: f4c4bb36ca3f4600 RBX: 1ffff92003a0fe04 RCX: ffffffff816a3aca
RDX: dffffc0000000000 RSI: ffffffff8aebd020 RDI: 0000000000000001
RBP: ffffc9001d07f090 R08: dffffc0000000000 R09: fffffbfff2050666
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: 1ffff92003a0fe00 R14: ffffc9001d07f020 R15: 0000000000000246
__debug_check_no_obj_freed lib/debugobjects.c:1022 [inline]
debug_check_no_obj_freed+0x58d/0x610 lib/debugobjects.c:1043
free_pages_prepare mm/page_alloc.c:1466 [inline]
free_pcp_prepare mm/page_alloc.c:1510 [inline]
free_unref_page_prepare+0x319/0x1120 mm/page_alloc.c:3388
free_unref_page+0x98/0x570 mm/page_alloc.c:3484
free_large_kmalloc+0xfb/0x190 mm/slab_common.c:932
skb_free_head net/core/skbuff.c:760 [inline]
skb_release_data+0x5de/0x7a0 net/core/skbuff.c:789
skb_release_all net/core/skbuff.c:854 [inline]
__kfree_skb net/core/skbuff.c:868 [inline]
kfree_skb_reason+0x16f/0x390 net/core/skbuff.c:891
l2tp_xmit_skb+0x935/0x17c0 net/l2tp/l2tp_core.c:1109
pppol2tp_sendmsg+0x388/0x5f0 net/l2tp/l2tp_ppp.c:318
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
kernel_sendmsg+0xf5/0x130 net/socket.c:756
sock_no_sendpage+0x162/0x1e0 net/core/sock.c:3222
kernel_sendpage+0x26a/0x640 net/socket.c:3563
sock_sendpage+0x7f/0xb0 net/socket.c:1059
pipe_to_sendpage+0x260/0x350 fs/splice.c:361
splice_from_pipe_feed fs/splice.c:415 [inline]
__splice_from_pipe+0x33b/0x890 fs/splice.c:559
splice_from_pipe fs/splice.c:594 [inline]
generic_splice_sendpage+0x195/0x220 fs/splice.c:743
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0xe3/0x1c0 fs/splice.c:931
splice_direct_to_actor+0x4c0/0xbd0 fs/splice.c:886
do_splice_direct+0x27f/0x3c0 fs/splice.c:974
do_sendfile+0x61c/0xff0 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1323 [inline]
__se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1309
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fb80e28c169
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb80ef60168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fb80e3ac050 RCX: 00007fb80e28c169
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00007fb80e2e7ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 000080001d00c0d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffec5bd543f R14: 00007fb80ef60300 R15: 0000000000022000
</TASK>


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[syzbot]

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