INFO: task hung in rmap_walk_file

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4ba8e26127c3 Linux 4.14.262
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16e6d067b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=51e11aabddb4cf62
dashboard link: https://syzkaller.appspot.com/bug?extid=0be4c82fad7f0f731ed7
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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+0be4c8...@syzkaller.appspotmail.com

Bluetooth: hci4 command 0x0406 tx timeout
Bluetooth: hci3 command 0x0406 tx timeout
Bluetooth: hci2 command 0x0406 tx timeout
Bluetooth: hci0 command 0x0406 tx timeout
Bluetooth: hci5 command 0x0406 tx timeout
INFO: task kswapd0:1946 blocked for more than 140 seconds.
Not tainted 4.14.262-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kswapd0 D28632 1946 2 0x80000000
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
__rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
rwsem_down_read_failed+0x1e6/0x350 kernel/locking/rwsem-xadd.c:309
call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94
__down_read arch/x86/include/asm/rwsem.h:66 [inline]
down_read+0x44/0x80 kernel/locking/rwsem.c:26
i_mmap_lock_read include/linux/fs.h:483 [inline]
rmap_walk_file+0x50e/0x7c0 mm/rmap.c:1828
rmap_walk+0xc4/0x150 mm/rmap.c:1857
try_to_unmap+0x243/0x2c0 mm/rmap.c:1673
shrink_page_list+0x1045/0x2fd0 mm/vmscan.c:1197
shrink_inactive_list+0x467/0x16c0 mm/vmscan.c:1825
shrink_list mm/vmscan.c:2177 [inline]
shrink_node_memcg+0x7a8/0x1190 mm/vmscan.c:2445


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[syzbot]

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