[v6.6] INFO: rcu detected stall in kcov_close (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: eac8889a3a1c Linux 6.6.140
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17d96b06580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5b35c4db8465904
dashboard link: https://syzkaller.appspot.com/bug?extid=5471950bb80340c1d274
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/284081ee4b1a/disk-eac8889a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6503c72409ee/vmlinux-eac8889a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5e529dbebdcb/bzImage-eac8889a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+547195...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P23871/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=165925, q=456335 ncpus=2)
task:syz.7.4897 state:R running task stack:25928 pid:23871 ppid:20866 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:_compound_head include/linux/page-flags.h:248 [inline]
RIP: 0010:page_memcg include/linux/memcontrol.h:445 [inline]
RIP: 0010:mod_memcg_page_state+0x150/0x930 include/linux/memcontrol.h:998
Code: 00 48 c7 c2 a0 39 d5 8a e8 4d 1f 97 ff 4c 8d 73 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 93 9c 0d 00 4d 8b 36 <4c> 89 f6 48 83 e6 01 31 ff e8 72 65 b5 ff 4c 89 f0 48 83 e0 01 4c
RSP: 0018:ffffc90012cbf7e0 EFLAGS: 00000246
RAX: 1ffffd4000194591 RBX: ffffea0000ca2c80 RCX: ffff88801ba88000
RDX: 0000000000000000 RSI: ffffffff8b1c9840 RDI: ffffffff8b1c9800
RBP: ffffc90012cbf8e0 R08: dffffc0000000000 R09: 1ffffffff2238ea0
R10: dffffc0000000000 R11: fffffbfff2238ea1 R12: dffffc0000000000
R13: 1ffff92002597f04 R14: 0000000000000000 R15: 0000000000000000
vfree+0x195/0x320 mm/vmalloc.c:2863
kcov_put kernel/kcov.c:438 [inline]
kcov_close+0x2b/0x50 kernel/kcov.c:534
__fput+0x234/0x970 fs/file_table.c:384
task_work_run+0x1d4/0x260 kernel/task_work.c:245
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0x95a/0x2460 kernel/exit.c:884
do_group_exit+0x21b/0x2d0 kernel/exit.c:1026
get_signal+0x12fc/0x13f0 kernel/signal.c:2902
arch_do_signal_or_restart+0xc2/0x800 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f244bb9ce59
RSP: 002b:00007f244ca70028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: 0000000000004000 RBX: 00007f244be16090 RCX: 00007f244bb9ce59
RDX: 000000000000fdbc RSI: 0000200000000500 RDI: 0000000000000006
RBP: 00007f244bc32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f244be16128 R14: 00007f244be16090 R15: 00007ffe07a6b8f8
</TASK>


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