syzbot has bisected this bug to:
commit 9c61acffe2b8833152041f7b6a02d1d0a17fd378
Author: Song Liu <songliubraving@xxxxxx>
Date: Wed Oct 23 00:24:28 2019 +0000
mm,thp: recheck each page before collapsing file THP
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15be4e14e00000
start commit: 49afce6d Add linux-next specific files for 20191031
git tree: linux-next
final crash: https://syzkaller.appspot.com/x/report.txt?x=17be4e14e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=13be4e14e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=3c5f119b33031056
dashboard link: https://syzkaller.appspot.com/bug?extid=62ebe501c1ce9a91f68c
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14c162f4e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=131b5eb8e00000
Reported-by: syzbot+62ebe501c1ce9a91f68c@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 9c61acffe2b8 ("mm,thp: recheck each page before collapsing file THP")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
