Re: possible deadlock in shmem_mfill_atomic_pte

[syzbot]

syzbot has bisected this bug to:

commit 71725ed10c40696dc6bdccf8e225815dcef24dba
Author: Hugh Dickins <hughd@xxxxxxxxxx>
Date:   Tue Apr 7 03:07:57 2020 +0000

    mm: huge tmpfs: try to split_huge_page() when punching hole

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17c463e7e00000
start commit:   ab6f762f printk: queue wake_up_klogd irq_work only if per-..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=142463e7e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=102463e7e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3010ccb0f380f660
dashboard link: https://syzkaller.appspot.com/bug?extid=e27980339d305f2dbfd9
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12d3c5afe00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15e7f51be00000

Reported-by: syzbot+e27980339d305f2dbfd9@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 71725ed10c40 ("mm: huge tmpfs: try to split_huge_page() when punching hole")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection