From: Mike Kravetz <mike.kravetz@oracle.com>
To: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Yang Shi <shy828301@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
syzbot <syzbot+152d76c44ba142f8992b@syzkaller.appspotmail.com>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, llvm@lists.linux.dev, nathan@kernel.org,
ndesaulniers@google.com, songmuchun@bytedance.com,
syzkaller-bugs@googlegroups.com, trix@redhat.com
Subject: Re: [syzbot] general protection fault in PageHeadHuge
Date: Sat, 24 Sep 2022 12:01:16 -0700 [thread overview]
Message-ID: <Yy9T/JmVb4ymf6WM@monkey> (raw)
In-Reply-To: <Yy8dBrmvDmqlsRXE@x1n>
On 09/24/22 11:06, Peter Xu wrote:
>
> Sorry I forgot to reply on this one.
>
> I didn't try linux-next, but I can easily reproduce this with mm-unstable
> already, and I verified that Hugh's patch fixes the problem for shmem.
>
> When I was testing I found hugetlb selftest is broken too but with some
> other errors:
>
> $ sudo ./userfaultfd hugetlb 100 10
> ...
> bounces: 6, mode: racing ver read, ERROR: unexpected write fault (errno=0, line=779)
>
> The failing check was making sure all MISSING events are not triggered by
> writes, but frankly I don't really know why it's required, and that check
> existed since the 1st commit when test was introduced.
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c47174fc362a089b1125174258e53ef4a69ce6b8
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/vm/userfaultfd.c?id=c47174fc362a089b1125174258e53ef4a69ce6b8#n291
>
> And obviously some recent hugetlb-related change caused that to happen.
>
> Dropping that check can definitely work, but I'll have a closer look soon
> too to make sure I didn't miss something. Mike, please also let me know if
> you are aware of this problem.
>
Peter, I am not aware of this problem. I really should make running ALL
hugetlb tests part of my regular routine.
If you do not beat me to it, I will take a look in the next few days.
--
Mike Kravetz
next prev parent reply other threads:[~2022-09-24 19:01 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-23 16:05 [syzbot] general protection fault in PageHeadHuge syzbot
2022-09-23 21:11 ` Mike Kravetz
2022-09-23 21:37 ` Yang Shi
2022-09-24 0:14 ` Hugh Dickins
2022-09-24 0:18 ` Nathan Chancellor
2022-09-24 7:28 ` Hugh Dickins
2022-09-24 0:58 ` Peter Xu
2022-09-24 15:06 ` Peter Xu
2022-09-24 19:01 ` Mike Kravetz [this message]
2022-09-26 0:11 ` Peter Xu
2022-09-27 16:24 ` Mike Kravetz
2022-09-27 16:45 ` Peter Xu
2022-09-29 23:33 ` Mike Kravetz
2022-09-30 1:29 ` Peter Xu
2022-09-30 1:35 ` Peter Xu
2022-09-30 16:05 ` Peter Xu
2022-09-30 21:38 ` Mike Kravetz
2022-10-01 2:47 ` Peter Xu
2022-10-01 3:01 ` Peter Xu
2022-10-03 1:16 ` Mike Kravetz
2022-10-03 15:24 ` Peter Xu
2022-09-25 18:55 ` Andrew Morton
2022-09-24 21:56 ` Matthew Wilcox
2022-09-27 4:32 ` Hugh Dickins
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