Re: possible deadlock in mnt_want_write

[syzbot]

syzbot has bisected this bug to:

commit 8e54cadab447dae779f80f79c87cbeaea9594f60
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date:   Sun Nov 27 01:05:42 2016 +0000

    fix default_file_splice_read()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=15147a36e00000
start commit:   6d906f99 Merge tag 'arm64-fixes' of git://git.kernel.org/p..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=17147a36e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=13147a36e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=856fc6d0fbbeede9
dashboard link: https://syzkaller.appspot.com/bug?extid=ae82084b07d0297e566b
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=111767b7200000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1611ab2d200000

Reported-by: syzbot+ae82084b07d0297e566b@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 8e54cadab447 ("fix default_file_splice_read()")

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