From: Peter Xu <peterx@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrea Arcangeli <aarcange@redhat.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Nadav Amit <nadav.amit@gmail.com>, Li Wang <liwan@redhat.com>
Subject: Re: [PATCH] mm/userfaultfd: selftests: Fix memory corruption with thp enabled
Date: Fri, 24 Sep 2021 10:14:21 -0400 [thread overview]
Message-ID: <YU3dPTsNWVhEo/5y@t490s> (raw)
In-Reply-To: <20210923191941.da28da4400c11a3241a07acf@linux-foundation.org>
On Thu, Sep 23, 2021 at 07:19:41PM -0700, Andrew Morton wrote:
> On Thu, 23 Sep 2021 19:25:12 -0400 Peter Xu <peterx@redhat.com> wrote:
>
> > In RHEL's gating selftests we've encountered memory corruption in the uffd
> > event test even with upstream kernel:
> >
> > ...
> >
> >
> > We can mark the Fixes tag upon 0db282ba2c12 as it's reported to only happen
> > there, however the real "Fixes" IMHO should be 8ba6e8640844, as before that
> > commit we'll always do explicit release_pages() before registration of uffd,
> > and 8ba6e8640844 changed that logic by adding extra unmap/map and we didn't
> > release the pages at the right place. Meanwhile I don't have a solid glue
> > anyway on whether posix_memalign() could always avoid triggering this bug,
> > hence it's safer to attach this fix to commit 8ba6e8640844.
> >
>
> Thanks. I added a cc:stable to this. I don't think we want selftests
> in older kernels to be falsely reporting kernel bugs?
Not sure how we normally handle such case for selftests, but I agree.
Btw, 8ba6e8640844 is merged in 5.14, so the only stable branch that will need
it will be 5.14.y; it can be applied cleanly there.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-09-24 14:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 23:25 [PATCH] mm/userfaultfd: selftests: Fix memory corruption with thp enabled Peter Xu
2021-09-24 2:19 ` Andrew Morton
2021-09-24 14:14 ` Peter Xu [this message]
2021-09-24 17:21 ` Axel Rasmussen
2021-09-24 19:59 ` Peter Xu
2021-09-27 17:34 ` Axel Rasmussen
2021-09-27 17:39 ` Peter Xu
2021-09-27 17:36 ` Peter Xu
2021-09-27 17:49 ` Axel Rasmussen
2021-09-27 20:37 ` Peter Xu
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