On Mon, 9 Jul 2018, Matthew Wilcox wrote: > On Fri, Jul 06, 2018 at 06:19:02PM -0700, syzbot wrote: > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 526674536360 Add linux-next specific files for 20180706 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=116d16fc400000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=c8d1cfc0cb798e48 > > dashboard link: https://syzkaller.appspot.com/bug?extid=b8e0dfee3fd8c9012771 > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=170e462c400000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15f1ba2c400000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+b8e0dfee3fd8c9012771@xxxxxxxxxxxxxxxxxxxxxxxxx > > #syz fix: shmem: Convert shmem_add_to_page_cache to XArray I don't see the patch, but I do see a diff in shmem_add_to_page_cache() between mmotm 4.18.0-rc3-mm1 and current mmotm 4.18.0-rc5-mm1, relating to use of xas_create_range(). Whether or not that fixed syzbot's kernel BUG at mm/shmem.c:815! I don't know, but I'm afraid it has not fixed linux-next breakage of huge tmpfs: I get a similar page_to_pgoff BUG at mm/filemap.c:1466! Please try something like mount -o remount,huge=always /dev/shm cp /dev/zero /dev/shm Writing soon crashes in find_lock_entry(), looking up offset 0x201 but getting the page for offset 0x3c1 instead. I've spent a while on it, but better turn over to you, Matthew: my guess is that xas_create_range() does not create the layout you expect from it. Thanks, Hugh
