From: Kiryl Shutsemau <kirill@shutemov.name>
To: Lance Yang <lance.yang@linux.dev>
Cc: Hugh Dickins <hughd@google.com>,
akpm@linux-foundation.org, david@redhat.com,
lorenzo.stoakes@oracle.com, ziy@nvidia.com,
baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com,
npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com,
baohua@kernel.org, ioworker0@gmail.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH mm-new 1/3] mm/khugepaged: skip unsuitable VMAs earlier in khugepaged_scan_mm_slot()
Date: Tue, 16 Sep 2025 10:29:11 +0100 [thread overview]
Message-ID: <ol447ofo44vwtyfwg3zrdtcdlkfzzmx4rre6qhyotmwvecnec4@usa3nonuk2sn> (raw)
In-Reply-To: <a0ec4014-384b-4c04-bf0b-777c989eabcb@linux.dev>
On Tue, Sep 16, 2025 at 02:21:26PM +0800, Lance Yang wrote:
> Users of mlock() expect low and predictable latency. THP collapse is a
> heavy operation that introduces exactly the kind of unpredictable delays
> they want to avoid. It has to unmap PTEs, copy data from the small folios
> to a new THP, and then remap the THP back to the PMD ;)
Generally, we allow minor page faults into mlocked VMAs and avoid major.
This is minor page fault territory in my view.
Also it is very similar to what compaction does and we allow compaction
of mlocked VMA by default, unless sysctl vm.compact_unevictable_allowed
is set to zero.
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2025-09-16 9:29 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-14 14:35 [PATCH mm-new 0/3] mm/khugepaged: optimize collapse candidate detection Lance Yang
2025-09-14 14:35 ` [PATCH mm-new 1/3] mm/khugepaged: skip unsuitable VMAs earlier in khugepaged_scan_mm_slot() Lance Yang
2025-09-14 16:16 ` Dev Jain
2025-09-15 3:02 ` Lance Yang
2025-09-16 5:32 ` Hugh Dickins
2025-09-16 6:21 ` Lance Yang
2025-09-16 6:42 ` Hugh Dickins
2025-09-16 7:05 ` Lance Yang
2025-09-16 9:29 ` Kiryl Shutsemau [this message]
2025-09-16 9:39 ` Lorenzo Stoakes
2025-09-16 9:48 ` Kiryl Shutsemau
2025-09-16 9:58 ` Lorenzo Stoakes
2025-09-16 10:00 ` Lance Yang
2025-09-16 9:59 ` Lance Yang
2025-09-14 14:35 ` [PATCH mm-new 2/3] mm: clean up and expose is_guard_pte_marker() Lance Yang
2025-09-14 16:38 ` Dev Jain
2025-09-15 4:24 ` Lance Yang
2025-09-15 13:54 ` Lorenzo Stoakes
2025-09-15 14:26 ` Lance Yang
2025-09-17 10:32 ` David Hildenbrand
2025-09-14 14:35 ` [PATCH mm-new 3/3] mm/khugepaged: abort collapse scan on guard PTEs Lance Yang
2025-09-14 17:03 ` Dev Jain
2025-09-15 3:36 ` Lance Yang
2025-09-15 14:08 ` Lorenzo Stoakes
2025-09-15 14:42 ` Lance Yang
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