From: Matthew Wilcox <willy@infradead.org>
To: Usama Arif <usama.arif@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.org>,
david@kernel.org, lorenzo.stoakes@oracle.com, linux-mm@kvack.org,
fvdl@google.com, hannes@cmpxchg.org, riel@surriel.com,
shakeel.butt@linux.dev, kas@kernel.org, baohua@kernel.org,
dev.jain@arm.com, baolin.wang@linux.alibaba.com,
npache@redhat.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com,
vbabka@suse.cz, lance.yang@linux.dev,
linux-kernel@vger.kernel.org, kernel-team@meta.com
Subject: Re: [RFC 1/2] mm: thp: allocate PTE page tables lazily at split time
Date: Wed, 11 Feb 2026 19:28:39 +0000 [thread overview]
Message-ID: <aYzYZ-QqQGH-dNEQ@casper.infradead.org> (raw)
In-Reply-To: <20260211125507.4175026-2-usama.arif@linux.dev>
On Wed, Feb 11, 2026 at 04:49:45AM -0800, Usama Arif wrote:
> - Memory reclaim (try_to_unmap()): Returns false, folio rotated back
> LRU, retried in next reclaim cycle.
I was advised to ask my stupid question ...
Why do we still try to split the PMD in reclaim? I understand we're
about to swap the folio out and we'll need to put a swap entry in the page
table so we can find it again. But can't we now store swap entries at the
PMD level, or are we still forced to store 512 entries at the PTE level?
next prev parent reply other threads:[~2026-02-11 19:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-11 12:49 [RFC 0/2] mm: thp: split time allocation of page table for THPs Usama Arif
2026-02-11 12:49 ` [RFC 1/2] mm: thp: allocate PTE page tables lazily at split time Usama Arif
2026-02-11 13:25 ` David Hildenbrand (Arm)
2026-02-11 13:38 ` Usama Arif
2026-02-12 12:13 ` Ritesh Harjani
2026-02-12 15:25 ` Usama Arif
2026-02-12 15:39 ` David Hildenbrand (Arm)
2026-02-12 16:46 ` Ritesh Harjani
2026-02-11 13:35 ` David Hildenbrand (Arm)
2026-02-11 13:46 ` Kiryl Shutsemau
2026-02-11 13:47 ` Usama Arif
2026-02-11 19:28 ` Matthew Wilcox [this message]
2026-02-11 19:55 ` David Hildenbrand (Arm)
2026-02-11 12:49 ` [RFC 2/2] mm: thp: add THP_SPLIT_PMD_PTE_ALLOC_FAILED counter Usama Arif
2026-02-11 13:27 ` David Hildenbrand (Arm)
2026-02-11 13:31 ` Usama Arif
2026-02-11 13:36 ` David Hildenbrand (Arm)
2026-02-11 13:42 ` Usama Arif
2026-02-11 13:38 ` David Hildenbrand (Arm)
2026-02-11 13:43 ` Usama Arif
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