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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dcbcab9d7079 Linux 6.1.174
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=171e192e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4dd3c1715f0a309b
dashboard link: https://syzkaller.appspot.com/bug?extid=4d82a4b98897d154a584
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/0f3e0db767ff/disk-dcbcab9d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d14e7b82c164/vmlinux-dcbcab9d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/52745da582ab/bzImage-dcbcab9d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4d82a4...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-...D } 2690 jiffies s: 1229 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4564 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:lookup_object lib/debugobjects.c:194 [inline]
RIP: 0010:lookup_object_or_alloc lib/debugobjects.c:565 [inline]
RIP: 0010:debug_object_activate+0x6d/0x4f0 lib/debugobjects.c:700
Code: 48 0f af c8 48 c1 e9 2f 83 e1 f8 4c 8d a4 c9 e0 e4 e0 96 48 8d bc c9 e8 e4 e0 96 48 89 7c 24 08 e8 28 eb 22 06 48 89 44 24 20 <4c> 89 e0 48 c1 e8 03 80 3c 28 00 74 08 4c 89 e7 e8 3e d2 bd fd 4c
RSP: 0018:ffffc900001e0ca8 EFLAGS: 00000046
RAX: 0000000000000802 RBX: ffff8880557c5340 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc900001e0b80
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200003c170 R12: ffffffff96ed6388
R13: dffffc0000000000 R14: ffffffff8a8e0980 R15: ffff8880b8f2a640
FS: 000055558284c500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbb2cc16038 CR3: 000000002b623000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
debug_hrtimer_activate kernel/time/hrtimer.c:448 [inline]
debug_activate kernel/time/hrtimer.c:503 [inline]
enqueue_hrtimer+0x30/0x3f0 kernel/time/hrtimer.c:1105
__run_hrtimer kernel/time/hrtimer.c:1764 [inline]
__hrtimer_run_queues+0x685/0xd50 kernel/time/hrtimer.c:1811
hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:35 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:lock_release+0x156/0x920 kernel/locking/lockdep.c:5678
Code: 00 00 83 3b 00 0f 85 6b 04 00 00 4c 89 74 24 08 43 c6 44 2f 08 00 48 c7 84 24 a0 00 00 00 00 00 00 00 9c 8f 84 24 a0 00 00 00 <48> 8b 84 24 a0 00 00 00 48 89 44 24 50 43 c6 44 2f 08 f8 fa 48 c7
RSP: 0018:ffffc900048777e0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8880299e8adc RCX: 7226729236801500
RDX: 0000000000000000 RSI: ffffffff8adf1b40 RDI: ffffffff8adf1b00
RBP: ffffc900048778f8 R08: ffffffff8e200c2f R09: 1ffffffff1c40185
R10: dffffc0000000000 R11: fffffbfff1c40186 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8880299e8000 R15: 1ffff9200090ef08
page_add_file_rmap+0x8d8/0x1500 mm/rmap.c:1331
insert_page_into_pte_locked+0x1c5/0x490 mm/memory.c:1867
insert_page mm/memory.c:1893 [inline]
vm_insert_page+0x3e3/0x580 mm/memory.c:2057
kcov_mmap+0x7d/0xd0 kernel/kcov.c:504
call_mmap include/linux/fs.h:2270 [inline]
mmap_file+0x5d/0xb0 mm/util.c:1109
__mmap_region mm/mmap.c:2772 [inline]
mmap_region+0xdda/0x1ca0 mm/mmap.c:2916
do_mmap+0x964/0xfd0 mm/mmap.c:1436
vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:520
ksys_mmap_pgoff+0x516/0x6f0 mm/mmap.c:1482
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fbb2c99cbc2
Code: 4f 01 00 0f 1f 44 00 00 41 f7 c1 ff 0f 00 00 75 27 55 89 cd 53 48 89 fb 48 85 ff 74 3b 41 89 ea 48 89 df b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 6e 5b 5d c3 0f 1f 00 48 c7 c0 e8 ff ff ff 64
RSP: 002b:00007ffceddd5a38 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fbb2bffd000 RCX: 00007fbb2c99cbc2
RDX: 0000000000000003 RSI: 0000000000400000 RDI: 00007fbb2bffd000
RBP: 0000000000000011 R08: 00000000000000d9 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000206 R12: 0000000000000003
R13: 0000000000000003 R14: 00007ffceddd5ca8 R15: 0000000000000000
</TASK>


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