From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Zi Yan <ziy@nvidia.com>,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <ljs@kernel.org>, Rik van Riel <riel@surriel.com>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>, Harry Yoo <harry@kernel.org>,
Jann Horn <jannh@google.com>, Lance Yang <lance.yang@linux.dev>,
Kyle Zeng <kylebot@openai.com>
Cc: stable@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/rmap: don't discard lazyfree THPs at PMD level
Date: Mon, 12 Oct 2026 12:25:45 +0200 [thread overview]
Message-ID: <342aa9c4-e100-4650-bb3a-89bd9d4b0eb0@kernel.org> (raw)
In-Reply-To: <20261009-lazyfree-stable-fix-v1-1-70997958ef8d@nvidia.com>
On 10/10/26 04:08, Zi Yan wrote:
> __discard_anon_folio_pmd_locked() clears a lazyfree THP PMD before it knows
> whether the folio can be discarded, and restores it if the folio was
> redirtied or has extra references. A concurrent munmap() or
> MREMAP_DONTUNMAP skips the temporary none PMD and unlinks the VMA from its
> anon_vma, so the folio stays mapped after the anon_vma is freed and a later
> rmap walk uses the freed anon_vma.
>
> Using an invalidated PMD instead of a cleared one requires additional arch
> code fixes. Instead, disable the PMD level discard of lazyfree THPs, as
> before commit 735ecdfaf4e8 ("mm/vmscan: avoid split lazyfree THP during
> shrink_folio_list()").
>
Maybe mention here that we leave the infrastructure around to re-enable it once
fixes?
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
next prev parent reply other threads:[~2026-10-12 10:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-10 2:08 Zi Yan
2026-10-10 2:14 ` Kyle Zeng
2026-10-10 2:28 ` Lance Yang
2026-10-12 10:25 ` David Hildenbrand (Arm) [this message]
2026-10-12 12:07 ` Lorenzo Stoakes (ARM)
2026-10-12 14:33 ` Zi Yan
2026-10-12 14:39 ` David Hildenbrand (Arm)
2026-10-12 15:22 ` Lorenzo Stoakes (ARM)
2026-10-12 15:22 ` Lorenzo Stoakes (ARM)
2026-10-12 20:37 ` Zi Yan
2026-10-13 14:29 ` Lorenzo Stoakes (ARM)
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