From: Lorenzo Stoakes <ljs@kernel•org>
To: "Michael S. Tsirkin" <mst@redhat•com>
Cc: linux-kernel@vger•kernel.org,
"David Hildenbrand (Arm)" <david@kernel•org>,
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virtualization@lists•linux.dev, linux-mm@kvack•org,
"Andrea Arcangeli" <aarcange@redhat•com>,
"Miaohe Lin" <linmiaohe@huawei•com>
Subject: Re: [PATCH v10 02/37] mm: memory-failure: serialize TestSetPageHWPoison with zone->lock
Date: Mon, 8 Jun 2026 15:14:51 +0100 [thread overview]
Message-ID: <aibMs9DXuhH_5F2Z@lucifer> (raw)
In-Reply-To: <20260608094153-mutt-send-email-mst@kernel.org>
On Mon, Jun 08, 2026 at 09:48:34AM -0400, Michael S. Tsirkin wrote:
> On Mon, Jun 08, 2026 at 10:43:21AM +0100, Lorenzo Stoakes wrote:
> > On Mon, Jun 08, 2026 at 04:34:23AM -0400, Michael S. Tsirkin wrote:
> > > TestSetPageHWPoison() is called without zone->lock, so its atomic
> > > update to page->flags can race with non-atomic flag operations
> > > that run under zone->lock in the buddy allocator.
> > >
> > > In particular, __free_pages_prepare() does:
> > >
> > > page->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP;
> > >
> > > This non-atomic read-modify-write, while correctly excluding
> > > __PG_HWPOISON from the mask, can still lose a concurrent
> > > TestSetPageHWPoison if the read happens before the poison bit
> > > is set and the write happens after. Follow-up patches in this
> > > series add similar non-atomic flag operations as well.
> > >
> > > Fix by acquiring zone->lock around TestSetPageHWPoison and
> > > around ClearPageHWPoison in the retry path. This
> > > serializes with all buddy flag manipulation. The cost is
> > > negligible: one lock/unlock in an extremely rare path
> > > (hardware memory errors).
> > >
> > > Note: SetPageHWPoison and TestClearPageHWPoison calls elsewhere
> > > in this file operate on pages already removed from the buddy
> > > allocator or on non-buddy pages (DAX, hugetlb), so they do not
> > > need zone->lock protection.
> > >
> > > Acked-by: Miaohe Lin <linmiaohe@huawei•com>
> > > Signed-off-by: Michael S. Tsirkin <mst@redhat•com>
> >
> > Can we have Fixes: and Cc: stable and also send this separately please?
> >
> > These patches seem like unrelated fixups that you've discovered along the way,
> > and don't belong as part of the already rather large series, unless I'm missing
> > something here.
> >
> > Thanks, Lorenzo
>
> I think you are mising that they are a dependency, not unrelated.
Then say so.
> For example, this issue gets worse with the patchset as there are more
> places that manipulate flags without atomics. No?
It's your job to make that case, not mine.
>
>
> You are welcome to send this to stable, but I think stable rules
> preclude theoretical bugfixes.
It's a dependency but also theoretical?
>
> As for Fixes: the issue has been there for decades. I wouldn't know
> what to attribute it for.
Again, your job.
>
>
> I guess I could send these separately, too, why not. Not sure
> what this accomplishes, but hey. But is that an ack? You want
> this fix merged even before the feature?
I already made the case as to why, as have other maintainers.
If you need to review what an ack looks like please consult
https://docs.kernel.org/process/5.Posting.html
Thanks, Lorenzo
next prev parent reply other threads:[~2026-06-08 14:15 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-08 8:33 [PATCH v10 00/37] mm/virtio: skip redundant zeroing of host-zeroed pages Michael S. Tsirkin
2026-06-08 8:34 ` [PATCH v10 01/37] mm: mempolicy: fix interleave index calculation Michael S. Tsirkin
2026-06-08 9:43 ` Lorenzo Stoakes
2026-06-08 8:34 ` [PATCH v10 02/37] mm: memory-failure: serialize TestSetPageHWPoison with zone->lock Michael S. Tsirkin
2026-06-08 9:43 ` Lorenzo Stoakes
2026-06-08 13:48 ` Michael S. Tsirkin
2026-06-08 14:14 ` Lorenzo Stoakes [this message]
2026-06-08 8:34 ` [PATCH v10 03/37] mm: page_alloc: propagate PageReported flag across buddy splits Michael S. Tsirkin
2026-06-08 9:52 ` Lorenzo Stoakes
2026-06-08 12:50 ` Matthew Wilcox
2026-06-08 8:34 ` [PATCH v10 04/37] mm: page_reporting: allow driver to set batch capacity Michael S. Tsirkin
2026-06-08 8:34 ` [PATCH v10 05/37] mm: hugetlb: remove dead alloc_hugetlb_folio stub Michael S. Tsirkin
2026-06-08 9:56 ` Lorenzo Stoakes
2026-06-08 8:35 ` [PATCH v10 06/37] mm: move vma_alloc_folio_noprof to page_alloc.c Michael S. Tsirkin
2026-06-08 10:05 ` Lorenzo Stoakes
2026-06-08 8:35 ` [PATCH v10 07/37] mm: thread user_addr through page allocator for cache-friendly zeroing Michael S. Tsirkin
2026-06-08 10:23 ` Lorenzo Stoakes
2026-06-08 11:06 ` Lorenzo Stoakes
2026-06-08 13:04 ` Matthew Wilcox
2026-06-08 13:09 ` Lorenzo Stoakes
2026-06-08 14:26 ` David Hildenbrand (Arm)
2026-06-08 14:31 ` Matthew Wilcox
2026-06-08 14:37 ` David Hildenbrand (Arm)
2026-06-08 14:44 ` Matthew Wilcox
2026-06-08 14:55 ` David Hildenbrand (Arm)
2026-06-08 11:08 ` David Hildenbrand (Arm)
2026-06-08 15:27 ` Zi Yan
2026-06-08 8:35 ` [PATCH v10 08/37] mm: add alloc_contig_frozen_pages_user " Michael S. Tsirkin
2026-06-08 10:29 ` Lorenzo Stoakes
2026-06-08 8:35 ` [PATCH v10 09/37] mm: hugetlb: thread user_addr through gigantic page allocation Michael S. Tsirkin
2026-06-08 8:36 ` [PATCH v10 10/37] mm: add folio_zero_user stub for configs without THP/HUGETLBFS Michael S. Tsirkin
2026-06-08 9:12 ` Lorenzo Stoakes
2026-06-08 8:36 ` [PATCH v10 11/37] mm: page_alloc: move prep_compound_page before post_alloc_hook Michael S. Tsirkin
2026-06-08 10:33 ` Lorenzo Stoakes
2026-06-08 8:36 ` [PATCH v10 12/37] mm: use folio_zero_user for user pages in post_alloc_hook Michael S. Tsirkin
2026-06-08 11:23 ` Lorenzo Stoakes
2026-06-08 8:36 ` [PATCH v10 13/37] mm: use __GFP_ZERO in vma_alloc_zeroed_movable_folio Michael S. Tsirkin
2026-06-08 10:39 ` Lorenzo Stoakes
2026-06-08 10:55 ` Lorenzo Stoakes
2026-06-08 8:37 ` [PATCH v10 14/37] mm: remove arch vma_alloc_zeroed_movable_folio overrides Michael S. Tsirkin
2026-06-08 11:29 ` Lorenzo Stoakes
2026-06-08 8:37 ` [PATCH v10 15/37] mm: alloc_anon_folio: pass raw fault address to vma_alloc_folio Michael S. Tsirkin
2026-06-08 11:35 ` Lorenzo Stoakes
2026-06-08 8:37 ` [PATCH v10 16/37] mm: alloc_swap_folio: " Michael S. Tsirkin
2026-06-08 11:37 ` Lorenzo Stoakes
2026-06-08 8:37 ` [PATCH v10 17/37] mm: page_reporting: skip redundant zeroing of host-zeroed reported pages Michael S. Tsirkin
2026-06-08 12:00 ` Lorenzo Stoakes
2026-06-08 8:38 ` [PATCH v10 18/37] mm: page_alloc: use aliasing checks instead of user_alloc_needs_zeroing Michael S. Tsirkin
2026-06-08 11:39 ` Lorenzo Stoakes
2026-06-08 8:38 ` [PATCH v10 19/37] mm: page_alloc: clear PG_zeroed on buddy merge if not both zero Michael S. Tsirkin
2026-06-08 11:47 ` Lorenzo Stoakes
2026-06-08 8:38 ` [PATCH v10 20/37] mm: page_alloc: preserve PG_zeroed in page_del_and_expand Michael S. Tsirkin
2026-06-08 8:38 ` [PATCH v10 21/37] mm: page_alloc: propagate PG_zeroed in split_large_buddy Michael S. Tsirkin
2026-06-08 8:38 ` [PATCH v10 22/37] mm: add free_frozen_pages_zeroed Michael S. Tsirkin
2026-06-08 12:06 ` Lorenzo Stoakes
2026-06-08 8:38 ` [PATCH v10 23/37] mm: page_alloc: skip kernel_init_pages for FPI_ZEROED when safe Michael S. Tsirkin
2026-06-08 12:18 ` Lorenzo Stoakes
2026-06-08 8:38 ` [PATCH v10 24/37] mm: add put_page_zeroed and folio_put_zeroed Michael S. Tsirkin
2026-06-08 12:25 ` Lorenzo Stoakes
2026-06-08 12:46 ` David Hildenbrand (Arm)
2026-06-08 14:08 ` Michael S. Tsirkin
2026-06-08 14:28 ` David Hildenbrand (Arm)
2026-06-08 8:39 ` [PATCH v10 25/37] mm: use __GFP_ZERO in alloc_anon_folio Michael S. Tsirkin
2026-06-08 12:29 ` Lorenzo Stoakes
2026-06-08 8:39 ` [PATCH v10 26/37] mm: vma_alloc_anon_folio_pmd: pass raw fault address to vma_alloc_folio Michael S. Tsirkin
2026-06-08 12:30 ` Lorenzo Stoakes
2026-06-08 8:39 ` [PATCH v10 27/37] mm: use __GFP_ZERO in vma_alloc_anon_folio_pmd Michael S. Tsirkin
2026-06-08 12:32 ` Lorenzo Stoakes
2026-06-08 8:39 ` [PATCH v10 28/37] mm: hugetlb: add gfp parameter and skip zeroing for zeroed pages Michael S. Tsirkin
2026-06-08 12:44 ` Lorenzo Stoakes
2026-06-08 8:39 ` [PATCH v10 29/37] mm: memfd: skip zeroing for zeroed hugetlb pool pages Michael S. Tsirkin
2026-06-08 12:47 ` Lorenzo Stoakes
2026-06-08 8:39 ` [PATCH v10 30/37] mm: page_reporting: add per-page zeroed bitmap for host feedback Michael S. Tsirkin
2026-06-08 8:39 ` [PATCH v10 31/37] virtio_balloon: submit reported pages as individual buffers Michael S. Tsirkin
2026-06-08 8:40 ` [PATCH v10 32/37] virtio_balloon: disable indirect descriptors Michael S. Tsirkin
2026-06-08 8:40 ` [PATCH v10 33/37] mm: page_reporting: add flush parameter with page budget Michael S. Tsirkin
2026-06-08 8:40 ` [PATCH v10 34/37] virtio_balloon: skip zeroing for host-zeroed reported pages Michael S. Tsirkin
2026-06-08 8:40 ` [PATCH v10 35/37] virtio_balloon: disable reporting zeroed optimization for confidential guests Michael S. Tsirkin
2026-06-08 8:40 ` [PATCH v10 36/37] mm: balloon: use put_page_zeroed for zeroed balloon pages Michael S. Tsirkin
2026-06-08 11:10 ` David Hildenbrand (Arm)
2026-06-08 8:40 ` [PATCH v10 37/37] virtio_balloon: implement VIRTIO_BALLOON_F_DEVICE_INIT_ON_INFLATE Michael S. Tsirkin
2026-06-08 9:17 ` [PATCH v10 00/37] mm/virtio: skip redundant zeroing of host-zeroed pages Lorenzo Stoakes
2026-06-08 12:52 ` Lorenzo Stoakes
2026-06-08 11:02 ` Vlastimil Babka (SUSE)
2026-06-08 11:13 ` Vlastimil Babka (SUSE)
2026-06-08 14:21 ` Matthew Wilcox
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