BUG: spinlock bad magic in page_vma_mapped_walk (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1bdc3d5be7e1 Merge tag 'powerpc-5.14-6' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15ad6599300000
kernel config: https://syzkaller.appspot.com/x/.config?x=96f0602203250753
dashboard link: https://syzkaller.appspot.com/bug?extid=ed3d945ecd664fc3b6cf
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
userspace arch: i386
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linu...@kvack.org]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ed3d94...@syzkaller.appspotmail.com

BUG: spinlock bad magic on CPU#1, kcompactd0/1660
lock: 0xffff8880001390c0, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
CPU: 1 PID: 1660 Comm: kcompactd0 Not tainted 5.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
do_raw_spin_lock+0x216/0x2b0 kernel/locking/spinlock_debug.c:112
spin_lock include/linux/spinlock.h:354 [inline]
map_pte mm/page_vma_mapped.c:52 [inline]
page_vma_mapped_walk+0xd87/0x24f0 mm/page_vma_mapped.c:261
remove_migration_pte+0x141/0xed0 mm/migrate.c:188
rmap_walk_anon+0x2ab/0x660 mm/rmap.c:2294
rmap_walk+0x12a/0x190 mm/rmap.c:2365
remove_migration_ptes mm/migrate.c:280 [inline]
__unmap_and_move mm/migrate.c:1072 [inline]
unmap_and_move mm/migrate.c:1136 [inline]
migrate_pages+0x1027/0x3970 mm/migrate.c:1411
compact_zone+0x1ab9/0x3860 mm/compaction.c:2399
proactive_compact_node+0x103/0x1c0 mm/compaction.c:2653
kcompactd+0x9a3/0xd10 mm/compaction.c:2923
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.