From: Matthew Wilcox <willy@infradead.org>
To: Usama Arif <usama.arif@linux.dev>
Cc: Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
david@kernel.org, Lorenzo Stoakes <ljs@kernel.org>,
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,
Vlastimil Babka <vbabka@kernel.org>,
lance.yang@linux.dev, linux-kernel@vger.kernel.org,
kernel-team@meta.com, maddy@linux.ibm.com, mpe@ellerman.id.au,
linuxppc-dev@lists.ozlabs.org, hca@linux.ibm.com,
gor@linux.ibm.com, agordeev@linux.ibm.com,
borntraeger@linux.ibm.com, svens@linux.ibm.com,
linux-s390@vger.kernel.org
Subject: Re: [v3 00/24] mm: thp: lazy PTE page table allocation at PMD split time
Date: Wed, 8 Apr 2026 20:49:46 +0100 [thread overview]
Message-ID: <adaxWs8BjCJB1aan@casper.infradead.org> (raw)
In-Reply-To: <3f9e8e12-2d51-4f2a-ada1-994ed24df284@linux.dev>
On Wed, Apr 08, 2026 at 04:06:29PM +0100, Usama Arif wrote:
> On 06/04/2026 00:34, Hugh Dickins wrote:
> > What would help a lot would be the implementation of swap entries
> > at the PMD level. Whether that would help enough, I'm sceptical:
> > I do think it's foolish to depend upon the availability of huge
> > contiguous swap extents, whatever the recent improvements there;
> > but it would at least be an arguable justification.
> >
> Thanks for pointing this out. I should have thought of this as I
> have been thinking about fork a lot for 1G THP and for this series.
>
> I am working on trying to make PMD level swap entires work. I hope
> to have a RFC soon.
I think you may have missed Hugh's point a little bit. If we do
support PMD-level swap entries, that means we have to be able to find
contiguous space in the swap space for 512 entries. I don't know how
hard that will be, but I can imagine it's not that easy.
prev parent reply other threads:[~2026-04-08 19:49 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-27 2:08 Usama Arif
2026-03-27 2:08 ` [v3 01/24] mm: thp: make split_huge_pmd functions return int for error propagation Usama Arif
2026-03-27 2:08 ` [v3 02/24] mm: thp: propagate split failure from vma_adjust_trans_huge() Usama Arif
2026-03-27 2:08 ` [v3 03/24] mm: thp: handle split failure in copy_huge_pmd() Usama Arif
2026-03-27 2:08 ` [v3 04/24] mm: thp: handle split failure in do_huge_pmd_wp_page() Usama Arif
2026-03-27 2:08 ` [v3 05/24] mm: thp: handle split failure in zap_pmd_range() Usama Arif
2026-03-30 14:13 ` Kiryl Shutsemau
2026-03-30 15:09 ` David Hildenbrand (Arm)
2026-03-27 2:08 ` [v3 06/24] mm: thp: handle split failure in wp_huge_pmd() Usama Arif
2026-03-27 2:08 ` [v3 07/24] mm: thp: retry on split failure in change_pmd_range() Usama Arif
2026-03-30 14:27 ` Kiryl Shutsemau
2026-03-27 2:08 ` [v3 08/24] mm: thp: handle split failure in follow_pmd_mask() Usama Arif
2026-03-27 2:08 ` [v3 09/24] mm: handle walk_page_range() failure from THP split Usama Arif
2026-03-27 2:08 ` [v3 10/24] mm: thp: handle split failure in mremap move_page_tables() Usama Arif
2026-03-27 2:08 ` [v3 11/24] mm: thp: handle split failure in userfaultfd move_pages() Usama Arif
2026-03-27 2:08 ` [v3 12/24] mm: thp: handle split failure in device migration Usama Arif
2026-03-27 2:08 ` [v3 13/24] mm: proc: handle split_huge_pmd failure in pagemap_scan Usama Arif
2026-03-27 2:08 ` [v3 14/24] powerpc/mm: handle split_huge_pmd failure in subpage_prot Usama Arif
2026-03-27 2:08 ` [v3 15/24] fs/dax: handle split_huge_pmd failure in dax_iomap_pmd_fault Usama Arif
2026-03-27 2:08 ` [v3 16/24] mm: huge_mm: Make sure all split_huge_pmd calls are checked Usama Arif
2026-03-30 14:41 ` Kiryl Shutsemau
2026-03-27 2:08 ` [v3 17/24] mm: thp: allocate PTE page tables lazily at split time Usama Arif
2026-03-27 2:09 ` [v3 18/24] mm: thp: remove pgtable_trans_huge_{deposit/withdraw} when not needed Usama Arif
2026-03-27 2:09 ` [v3 19/24] mm: thp: add THP_SPLIT_PMD_FAILED counter Usama Arif
2026-03-27 2:09 ` [v3 20/24] selftests/mm: add THP PMD split test infrastructure Usama Arif
2026-03-27 2:09 ` [v3 21/24] selftests/mm: add partial_mprotect test for change_pmd_range Usama Arif
2026-03-27 2:09 ` [v3 22/24] selftests/mm: add partial_mlock test Usama Arif
2026-03-27 2:09 ` [v3 23/24] selftests/mm: add partial_mremap test for move_page_tables Usama Arif
2026-03-27 2:09 ` [v3 24/24] selftests/mm: add madv_dontneed_partial test Usama Arif
2026-03-27 8:51 ` [v3 00/24] mm: thp: lazy PTE page table allocation at PMD split time David Hildenbrand (Arm)
2026-03-27 9:25 ` Lorenzo Stoakes (Oracle)
2026-03-27 14:40 ` Usama Arif
2026-03-27 14:34 ` Usama Arif
2026-04-05 23:34 ` Hugh Dickins
2026-04-08 15:06 ` Usama Arif
2026-04-08 19:49 ` Matthew Wilcox [this message]
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