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