On 11/13/22 16:36, Dmitry Vyukov wrote: > On Sat, 12 Nov 2022 at 15:03, syzbot > <syzbot+d07c65298d2c15eafcb0@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 1621b6eaebf7 Merge branch 'for-next/fixes' into for-kernelci > > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci > > console output: https://syzkaller.appspot.com/x/log.txt?x=13bd511e880000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=606e57fd25c5c6cc > > dashboard link: https://syzkaller.appspot.com/bug?extid=d07c65298d2c15eafcb0 > > compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2 > > userspace arch: arm64 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13315856880000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=173614d1880000 > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/82aa7741098d/disk-1621b6ea.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/f6be08c4e4c2/vmlinux-1621b6ea.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/296b6946258a/Image-1621b6ea.gz.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+d07c65298d2c15eafcb0@xxxxxxxxxxxxxxxxxxxxxxxxx > > This may have the same root cause as: > > possible deadlock in hugetlb_fault > https://lore.kernel.org/all/CACT4Y+ZWNV6ApzEv0UrsF2T8JWmXez_-H-EGMii-S_2JbXv07Q@xxxxxxxxxxxxxx/ > > and there is a potential explanation as to what may be the problem. Thanks Dmitry! An issue with this new hugetlb locking was previously reported and I have been working on a solution. When I look at the reproducer, I see that it is calling madvise(MADV_DONTNEED). This triggers the other issue and could certainly cause the issue reported here. Proposed patches are here and in next-20221111: https://lore.kernel.org/linux-mm/20221111232628.290160-1-mike.kravetz@xxxxxxxxxx/ I am currently trying to run the reproducer, but it is not reproducing quickly. Since this is a timing issue that as expected. Interesting that this report is run on arm64 and I am trying to reproduce on x86. Although, the issue is not architecture specific in any way. I'll keep looking, but am fairly confident this is the root cause. -- Mike Kravetz
