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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Matthew Wilcox , Chris Down , Suren Baghdasaryan , Mike Rapoport , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH mm-hotfixes] mm/huge_memory: fix memory corruption on huge zero page move Message-ID: References: <20260302170619.867056-1-lorenzo.stoakes@oracle.com> <901fec30-c5c2-46c5-b48d-f9a8f5e5c928@kernel.org> <20260302125032.313797b0ec908cd133f3ed82@linux-foundation.org> <20260303174226.1b9079ccd60164fe0b28a3e1@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260303174226.1b9079ccd60164fe0b28a3e1@linux-foundation.org> X-Rspamd-Queue-Id: AF38A14000C X-Stat-Signature: jqeuhh45oya66yi6su6xb8rfawiweocq X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1772624480-594436 X-HE-Meta: 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 TETjqcvG b9tK4KfeX5yTr76jYXXCr+soIFDTQHWDj8OQk45q7Wfz19r98Ee/mb7N7L5IUnYHsMwLuq+viJ7qEgUJuPHmtehZZST5lcU9+1VJLMFdACJAyHdFeBQZvVOii5Hu8EXkoiVqUhjzS2n5fJzP1Ko8XVWlKSiLITonn/tFcEJo0U2MsFQNw6t2s/hBHFmq7MT1Hd0MqhO/wUf8LKIRCS/RrKC9bLFM5gtBAjJGs5NwNaZSoHTzJgkwRj/7NZJnW9TpNv1frqx8ZQJq8O8VxFmYnCUsMy1XLZISBbtwBFBjV4LX1bptKAooWnNdcEQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 03, 2026 at 05:42:26PM -0800, Andrew Morton wrote: > On Tue, 3 Mar 2026 07:25:32 +0000 Lorenzo Stoakes wrote: > > > On Mon, Mar 02, 2026 at 12:50:32PM -0800, Andrew Morton wrote: > > > On Mon, 2 Mar 2026 17:19:15 +0000 Lorenzo Stoakes wrote: > > > > > > > On Mon, Mar 02, 2026 at 06:10:06PM +0100, David Hildenbrand (Arm) wrote: > > > > > There are already patches in flight: > > > > > > > > > > https://lore.kernel.org/r/aaBVaHs8rIkNcwM0@chrisdown.name > > > > > > > > Yup, if people would actually cc the right people I'd not have wasted my > > > > afternoon. > > > > > > > > Replying there. > > > > > > > > > > I'm not sure where this is headed but I'll queue this patch for now, to > > > get it some testing, to lessen duplicated bug reports and to generally track things. > > > > Hi Andrew - > > Who is a confused person! > > > We should drop my patch and take Chris's. > > "my patch" being "mm/huge_memory: fix memory corruption on huge zero > page move", I assume. Yes :) > > > However, life isn't so simple :) as there's been some confusion with his series > > since his email client seemed to mess up somehow and a couple patches need to be > > squashed on one another. > > > > So to make life easier, I enclose a squashed patch (combining the commit > > message from both), with my R-b, T-b tags attached, please replace my patch > > with this one. > > OK. I added your signed-off-by also. Thanks, probaby appropriate. > > > Also, could you make this into a 2 patch series with > > https://lore.kernel.org/linux-mm/aaBWG4fajXXbjpVN@chrisdown.name/ _after_ this > > one? > > Well, "mm/huge_memory: Fix use of NULL folio in move_pages_huge_pmd()" > is a cc:stable mm-hotfix and I don't think "selftests/mm: Add UFFDIO_MOVE > huge zeropage PMD regression test" is to be treated that way? > > If correct, I'd keep "selftests/mm: Add UFFDIO_MOVE huge zeropage PMD > regression test" as a standalone singleton in mmm-unstable. If you can _ensure_ the fix appears in the commit list and in -next _before_ the test then yes. > > > mm-unstable (I'm not sure why we're rushing changes there so quick...) had > > _only_ this regression test patch in it, so we were left with a kernel that > > splatted on running mm selftests, which is not what we want. > > But the regression fix "mm/huge_memory: fix memory corruption on huge > zero page move" was in mm-hotfixes, cc:stable? Chris sent 3 patches, the first two addressed the bug, the 3rd was the test. The first 2 had review feedback, but for some reason the test was taken, and then taken to mm-unstable almost immediately. (This is partly why I wasted my time tracking down the bug in mm-unstable and ended up independently fixing it...) I think things were confused by Chris's email client somehow messing up sending the series which we not threaded etc. > > > (It seems to me this is what mm-new is for, and it seems we have some holes in > > our testing still since this got thorugh). > > > > Please drop the patch you have for this already in mm-unstable and make sure we > > only have it _after_ the fix is applied :) > > I think you mean to drop "mm/huge_memory: fix memory corruption on huge > zero page move" from mm-hotfixes. Yes drop mine. > > > So we now have > > "mm/huge_memory: fix use of NULL folio in move_pages_huge_pmd()" in > mm-hotfixes, cc:stable > > "selftests/mm: add UFFDIO_MOVE huge zeropage PMD regression test" in > mm-unstable, not cc:stable. > > btw, "selftests/mm: add UFFDIO_MOVE huge zeropage PMD regression test" > still has a bunch of unaddressed review comments from David. I mean let's not have it in mm-unstable then? Things should only transition from mm-new to mm-unstable/-next if the review is in a good state. Generally we go easier on tests sure, but if there's any hint of it being a regression test we have to tread carefully, or we end up splatting people's kernels and cause unnecessary issues. > > Thanks, Lorenzo