From: Andrew Morton <akpm@linux-foundation.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: david@kernel.org, ljs@kernel.org, riel@surriel.com,
liam@infradead.org, vbabka@kernel.org, harry@kernel.org,
jannh@google.com, sj@kernel.org, ziy@nvidia.com,
balbirs@nvidia.com, linux-mm@kvack.org,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
stable@vger.kernel.org
Subject: Re: [PATCH] mm/page_vma_mapped: revalidate and do proper check before return device-private pmd
Date: Fri, 8 May 2026 14:51:21 -0700 [thread overview]
Message-ID: <20260508145121.35e2552d403b94ea6f748b90@linux-foundation.org> (raw)
In-Reply-To: <20260508013728.21285-1-richard.weiyang@gmail.com>
On Fri, 8 May 2026 01:37:28 +0000 Wei Yang <richard.weiyang@gmail.com> wrote:
> For pmd_trans_huge() and pmd_is_migration_entry(), we does following
> before return the pmd entry:
>
> * re-validate pmd entry
> * check PVMW_MIGRATION
> * check_pmd()
> * handle on pte level if split under us
>
> But for device-private pmd, we just return after pmd_lock(). This may
> lead to inproper situation.
What is "improper situation"?
> This patch fixes commit 65edfda6f3f2 ("mm/rmap: extend rmap and migration
> support device-private entries") by following the same pattern as
> pmd_trans_huge() and pmd_is_migration_entry().
>
> Fixes: 65edfda6f3f2 ("mm/rmap: extend rmap and migration support device-private entries")
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> Cc: David Hildenbrand <david@kernel.org>
> Cc: Balbir Singh <balbirs@nvidia.com>
> Cc: SeongJae Park <sj@kernel.org>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Cc: <stable@vger.kernel.org>
If we're to propose a fix for -stable backporting I believe we should
fully explain to -stable maintainers *why* we're making that proposal.
IOW, and not for the first time(!), what are the worst-case
userspace-visible effects of this bug?
next prev parent reply other threads:[~2026-05-08 21:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-08 1:37 [PATCH] mm/page_vma_mapped: revalidate and do proper check before return device-private pmd Wei Yang
2026-05-08 21:51 ` Andrew Morton [this message]
2026-05-10 1:22 ` Wei Yang
2026-05-08 22:48 ` Balbir Singh
2026-05-10 1:20 ` Wei Yang
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