From: Andrew Morton <akpm@linux-foundation.org>
To: James Houghton <jthoughton@google.com>
Cc: Lance Yang <lance.yang@linux.dev>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>, Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
liam@infradead.org, Nico Pache <nico.pache@linux.dev>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Usama Arif <usama.arif@linux.dev>,
Yang Shi <shy828301@gmail.com>,
zokeefe@google.com, hughd@google.com,
Kiryl Shutsemau <kas@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH v2] mm/khugepaged: Don't install PMDs in uffd-minor-registered VMAs
Date: Fri, 28 Aug 2026 18:38:01 -0700 [thread overview]
Message-ID: <20260828183801.04fd2d2a6af837cb45b60e0f@linux-foundation.org> (raw)
In-Reply-To: <CADrL8HV0nUDjr432S8AdTZ_HO8fACrFSCu8cS49vR4XJQa39zg@mail.gmail.com>
On Fri, 28 Aug 2026 18:18:11 -0700 James Houghton <jthoughton@google.com> wrote:
> On Fri, Aug 28, 2026 at 6:09 PM James Houghton <jthoughton@google.com> wrote:
> >
> > On Fri, Aug 28, 2026 at 5:33 PM Andrew Morton <akpm@linux-foundation.org> wrote:
> > > Wondering what Lance tested. Was he able to reproduce the bug?
> >
> > I assume he just re-ran my repro, but yeah I'm not sure, heh. Lance,
> > what did you test?
>
> Ah, just to be clear, I linked a repro on v1. Here[1] is that repro.
> Sorry, slipped my mind to also include it in the notes for this v2.
>
> [1] https://gist.github.com/48ca/d399bf534158e80241fb4937ef1ff664
Cool thanks, I'll slap this into the changelog.
# ./a.out
TAP version 13
1..1
madvise(MADV_COLLAPSE) succeeded
ioctl(UFFDIO_CONTINUE) failed: File exists (errno=17)
not ok 1 - memfd userfaultfd MINOR continue test
We do have a ton of uffd selftesting code in there. Adding this case
to uffd-unit-tests.c would presumably be pretty simple. We don't
really have a policy on adding a test-case after fixing something -
it's common practice but why? We already fixed it!
next prev parent reply other threads:[~2026-08-29 1:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-28 22:26 [PATCH v2] mm/khugepaged: Don't install PMDs in uffd-minor-registered VMAs James Houghton
2026-08-29 0:33 ` Andrew Morton
2026-08-29 1:09 ` James Houghton
2026-08-29 1:18 ` James Houghton
2026-08-29 1:38 ` Andrew Morton [this message]
2026-08-29 2:50 ` James Houghton
2026-08-29 1:29 ` Andrew Morton
2026-08-29 4:38 ` Lance Yang
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