On Mon, May 21, 2018 at 2:50 PM, Jan Kara <jack@xxxxxxx> wrote: > On Sun 20-05-18 23:07:02, syzbot wrote: >> syzbot has found a reproducer for the following crash on: >> >> HEAD commit: 771c577c23ba Linux 4.17-rc6 >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=108c9f37800000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=982e2df1b9e60b02 >> dashboard link: https://syzkaller.appspot.com/bug?extid=9a44753ac327c557796a >> compiler: gcc (GCC) 8.0.1 20180413 (experimental) >> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=1655584f800000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15134357800000 >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+9a44753ac327c557796a@xxxxxxxxxxxxxxxxxxxxxxxxx >> >> WARNING: CPU: 0 PID: 4577 at fs/ext4/inode.c:3894 >> ext4_set_page_dirty+0x28d/0x330 fs/ext4/inode.c:3894 >> Kernel panic - not syncing: panic_on_warn set ... > > Looking at the reproducer, this is the issue we have been speaking about at > LSF/MM - direct IO read dirties pages after writeback has written them out > and so we don't expect them to be dirtied. If someone told me I would not > believe this is possible to hit by fuzzing ;) Good job from the syzkaller > guys! Thanks, Jan! Very nice to hear. I believe we are not yet at the limit of what's possible :)
