* Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> [220427 13:52]: > * Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> [220427 13:20]: > > On Wed, 27 Apr 2022 06:15:20 -0700 syzbot <syzbot+7728e4ab5371cebc9c00@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > syzbot has found a reproducer for the following issue on: > > > > Thanks. > > > > userfaultfd_release() appears to have offended vma_merge(). > > Potentially apply_mlockall_flags() and not userfaultfd_release(). There > is a potential that the vma iterator is stale if a split/merge succeeds, > although KASAN should pick this up and KASAN is active according to the > config below. I've sent a patch for the mlockall issue after Qian Cai's > reported it to linux-mm. > > > > > I'm not seeing any changes in that area from Peter, but Liam's > > mapletree work changed things around a bit. Gents, could you please > > take a look? > > > > > > > HEAD commit: f02ac5c95dfd Add linux-next specific files for 20220427 > > > git tree: linux-next > > > console output: https://syzkaller.appspot.com/x/log.txt?x=105a33a2f00000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=e9256c70f586da8a > > > dashboard link: https://syzkaller.appspot.com/bug?extid=7728e4ab5371cebc9c00 > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15f76f82f00000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12b42c3cf00000 > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+7728e4ab5371cebc9c00@xxxxxxxxxxxxxxxxxxxxxxxxx > > > ... > > I cannot get this issue to trigger with the given tree and git repo with > my config. I will try again with the kernel config above. I was able to reproduce the issue using the config from syzkaller in my VM and can confirm it was the apply_mlockall_flags() bug also reported by Qian Cai [1]. The patch I sent earlier [2] fixes this issue as well. 1. https://lore.kernel.org/linux-mm/20220427161033.GA1935@qian/ 2. https://lore.kernel.org/linux-mm/20220427165139.5s3qcj2u5vqrvwlc@revolver/ Thanks, Liam
