From: Lance Yang <lance.yang@linux.dev>
To: david@kernel.org
Cc: akpm@linux-foundation.org, ziy@nvidia.com,
baolin.wang@linux.alibaba.com, hughd@google.com,
liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com,
dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev,
usama.arif@linux.dev, kas@kernel.org, zokeefe@google.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
mason@kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] mm/khugepaged: don't map folios that are not uptodate in MADV_COLLAPSE
Date: Fri, 6 Nov 2026 10:53:42 +0800 [thread overview]
Message-ID: <20261106025342.18229-1-lance.yang@linux.dev> (raw)
In-Reply-To: <20261105-set_huge_pmd_uptodate-v1-1-a78d8a1b7117@kernel.org>
On Thu, Nov 05, 2026 at 07:16:44PM +0100, David Hildenbrand (Arm) wrote:
>madvise(MADV_COLLAPSE) can map PMD-sized pagecache folios that are not
>uptodate. For example, shmem fallocate() can put such folios into the
>page cache.
>
>collapse_file() already refuses to proceed with folios that are not
>uptodate. Let's just do the same in try_collapse_pte_mapped_thp() and skip
>such folios, leaving handling to the page faults.
>
>Note that collapse_file() effectively clears shmem folios through
>shmem_get_folio(); let's keep this fix simple and simply let the page
>fault path deal with that.
>
>Fixes: 34488399fa08 ("mm/madvise: add file and shmem support to MADV_COLLAPSE")
>Reported-by: Chris Mason <mason@kernel.org>
>Cc: stable@vger.kernel.org
>Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
>---
Nice work1
Reviewed-by: Lance Yang <lance.yang@linux.dev>
prev parent reply other threads:[~2026-11-06 2:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-05 18:16 David Hildenbrand (Arm)
2026-11-05 19:34 ` Lorenzo Stoakes (ARM)
2026-11-05 19:58 ` Hugh Dickins
2026-11-05 20:09 ` Zi Yan
2026-11-05 21:24 ` Zach O'Keefe
2026-11-06 1:08 ` SJ Park
2026-11-06 2:49 ` Baolin Wang
2026-11-06 2:53 ` Lance Yang [this message]
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