[syzbot] [mm?] INFO: rcu detected stall in khugepaged (3)

[syzbot <syzbot+d2401aeb74cc84adba04@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    3708dd948844 Merge tag 'pm-7.2-rc6' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11ac703e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4e38b15c29e6a1d9
dashboard link: https://syzkaller.appspot.com/bug?extid=d2401aeb74cc84adba04
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c0390423374e/disk-3708dd94.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3130bf9c5dbf/vmlinux-3708dd94.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2c8fbf8aeba4/bzImage-3708dd94.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d2401aeb74cc84adba04@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P37/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=32265, q=1190 ncpus=2)
task:khugepaged      state:R  running task     stack:26864 pid:37    tgid:37    ppid:2      task_flags:0x200040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_release+0x2d7/0x3c0 kernel/locking/lockdep.c:5893
Code: 7d ca 11 00 00 00 00 eb b5 e8 55 ad 2e 0a f7 c3 00 02 00 00 74 b9 65 48 8b 05 45 38 ca 11 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d a2 33 b8
RSP: 0018:ffffc90000ad7028 EFLAGS: 00000286
RAX: 623a32d217845600 RBX: 0000000000000206 RCX: 0000000000000046
RDX: 0000000000000000 RSI: ffffffff8e4b3351 RDI: ffffffff8c4bdd80
RBP: ffff888020ea0ba0 R08: ffffc90000ad74d0 R09: 0000000000000000
R10: ffffc90000ad7158 R11: fffff5200015ae2d R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff8eb59c60 R15: ffff888020ea0000
 rcu_lock_release include/linux/rcupdate.h:310 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1183 [inline]
 unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 mm/page_owner.c:165
 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950
 __folio_put+0x4b3/0x590 mm/swap.c:112
 folio_put_refs include/linux/mm.h:2144 [inline]
 collapse_file mm/khugepaged.c:2643 [inline]
 collapse_scan_file+0x4285/0x5210 mm/khugepaged.c:2773
 collapse_single_pmd+0x2b1/0x3da0 mm/khugepaged.c:2808
 collapse_scan_mm_slot mm/khugepaged.c:2913 [inline]
 khugepaged_do_scan mm/khugepaged.c:2993 [inline]
 khugepaged+0xa00/0x1780 mm/khugepaged.c:3048
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup