[v6.1] INFO: rcu detected stall in schedule_tail (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ad16b162f21d Linux 6.1.172
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11f209ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f0605c5af04d7603
dashboard link: https://syzkaller.appspot.com/bug?extid=c7ef9668cfa7f53d0211
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/2188b271cf45/disk-ad16b162.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/356336b9737c/vmlinux-ad16b162.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3453b10f11f7/bzImage-ad16b162.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c7ef96...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P10488/1:b..l
(detected by 0, t=10503 jiffies, g=65049, q=30111 ncpus=2)
task:syz-executor state:R running task stack:29936 pid:10488 ppid:4282 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
irqentry_exit+0x63/0x70 kernel/entry/common.c:439
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:trace_lock_acquire include/trace/events/lock.h:24 [inline]
RIP: 0010:lock_acquire+0xdc/0x4a0 kernel/locking/lockdep.c:5633
Code: b8 bb 0c 0f 83 a2 01 00 00 45 89 f4 41 c1 ee 06 4a 8d 3c f5 e8 f3 1f 8e be 08 00 00 00 e8 fc 45 6f 00 4c 0f a3 25 bc b6 bb 0c <73> 0d e8 9d 32 08 00 84 c0 0f 84 2e 02 00 00 48 c7 c0 a4 28 20 8e
RSP: 0018:ffffc9000da97dc0 EFLAGS: 00000257
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81643d24
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e1ff3e8
RBP: ffffc9000da97ed0 R08: ffffffff8e1ff3ef R09: 1ffffffff1c3fe7d
R10: dffffc0000000000 R11: fffffbfff1c3fe7e R12: 0000000000000000
R13: 1ffff92001b52fc4 R14: 0000000000000000 R15: dffffc0000000000
rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
rcu_read_lock include/linux/rcupdate.h:791 [inline]
__task_pid_nr_ns+0x44/0x460 kernel/pid.c:497
task_pid_vnr include/linux/sched.h:1576 [inline]
schedule_tail+0x74/0xb0 kernel/sched/core.c:5184
ret_from_fork+0x8/0x30 arch/x86/entry/entry_64.S:280
</TASK>


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