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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c61bd26ae81a Linux 5.15.160
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10ee26dc980000
kernel config: https://syzkaller.appspot.com/x/.config?x=235f0e81ca937c17
dashboard link: https://syzkaller.appspot.com/bug?extid=f41fea23bf13656ef7cb
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d61a97eef8b9/disk-c61bd26a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ab4908b4b59b/vmlinux-c61bd26a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d818fd46802b/bzImage-c61bd26a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f41fea...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 ticks this GP) idle=249/1/0x4000000000000000 softirq=17762/17762 fqs=2048
(detected by 1, t=10505 jiffies, g=22925, q=1662)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5700 Comm: syz-executor.4 Not tainted 5.15.160-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:__lock_acquire+0xcc2/0x1ff0 kernel/locking/lockdep.c:4982
Code: f6 85 c0 0f 84 a6 08 00 00 48 c7 c0 c0 ff 3e 91 48 c1 e8 03 48 bf 00 00 00 00 00 fc ff df 0f b6 04 38 84 c0 0f 85 0e 0c 00 00 <83> 3d 27 41 dc 0f 00 75 44 48 8b 6c 24 58 8d 45 3f 85 ed 0f 49 c5
RSP: 0018:ffffc900000079e0 EFLAGS: 00000097
RAX: 0000000000000004 RBX: ffff888063056458 RCX: ffffffff913eff03
RDX: 0000000000000000 RSI: 0000000000000000 RDI: dffffc0000000000
RBP: ffff888063055940 R08: dffffc0000000000 R09: fffffbfff1f7f019
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000001
R13: ffff888063056428 R14: 0000000000000001 R15: ffff888063056478
FS: 0000555557280480(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f124ca4e008 CR3: 0000000061954000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<IRQ>
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
debug_object_activate+0x63/0x4e0 lib/debugobjects.c:693
debug_hrtimer_activate kernel/time/hrtimer.c:420 [inline]
debug_activate kernel/time/hrtimer.c:475 [inline]
enqueue_hrtimer+0x30/0x390 kernel/time/hrtimer.c:1084
__run_hrtimer kernel/time/hrtimer.c:1703 [inline]
__hrtimer_run_queues+0x6b6/0xcf0 kernel/time/hrtimer.c:1750
hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1812
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline]
__sysvec_apic_timer_interrupt+0x139/0x470 arch/x86/kernel/apic/apic.c:1102
sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1096
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:to_desc kernel/printk/printk_ringbuffer.c:357 [inline]
RIP: 0010:prb_read kernel/printk/printk_ringbuffer.c:1790 [inline]
RIP: 0010:_prb_read_valid+0x1cf/0xbd0 kernel/printk/printk_ringbuffer.c:1880
Code: 44 89 e9 d3 e0 f7 d0 23 44 24 08 48 89 44 24 38 4c 6b f8 58 48 8b 5c 24 50 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 43 2f 63 00 4c 03 7c 24 20 4c 8b 23
RSP: 0018:ffffc900031075e0 EFLAGS: 00000a02
RAX: 1ffffffff18ff825 RBX: ffffffff8c7fc128 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 000000000000000d RDI: 0000000000000020
RBP: ffffc900031077f0 R08: ffffffff8166fb41 R09: fffff52000620f3e
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffc90003107840
R13: 000000000000000d R14: ffffffff8c7fc120 R15: 000000000003c070
prb_read_valid_info+0x125/0x170 kernel/printk/printk_ringbuffer.c:1963
find_first_fitting_seq+0x21c/0x580 kernel/printk/printk.c:1463
syslog_print_all+0x1b3/0x800 kernel/printk/printk.c:1614
do_syslog+0x7a7/0x940 kernel/printk/printk.c:1693
__do_sys_syslog kernel/printk/printk.c:1771 [inline]
__se_sys_syslog kernel/printk/printk.c:1769 [inline]
__x64_sys_syslog+0x78/0x90 kernel/printk/printk.c:1769
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f124c922ee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc53fdc058 EFLAGS: 00000246 ORIG_RAX: 0000000000000067
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f124c922ee9
RDX: 000000000000003f RSI: 00007ffc53fdc140 RDI: 0000000000000003
RBP: 00007ffc53fdc140 R08: 0000000000000010 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc53fdc728
R13: 00007ffc53fdc728 R14: 0000000000000001 R15: 00000000fffffff1
</TASK>


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