From: David Hildenbrand <david@redhat.com>
To: Lance Yang <lance.yang@linux.dev>, akpm@linux-foundation.org
Cc: lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com,
baohua@kernel.org, baolin.wang@linux.alibaba.com,
dev.jain@arm.com, hughd@google.com, ioworker0@gmail.com,
kirill@shutemov.name, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, mpenttil@redhat.com, npache@redhat.com,
ryan.roberts@arm.com, ziy@nvidia.com, richard.weiyang@gmail.com
Subject: Re: [PATCH mm-new 1/1] mm/khugepaged: abort collapse scan on non-swap entries
Date: Wed, 24 Sep 2025 12:10:47 +0200 [thread overview]
Message-ID: <1282de5a-3dce-443d-91d1-111103140973@redhat.com> (raw)
In-Reply-To: <20250924100207.28332-1-lance.yang@linux.dev>
On 24.09.25 12:02, Lance Yang wrote:
> From: Lance Yang <lance.yang@linux.dev>
>
> The existing check in hpage_collapse_scan_pmd() is specific to uffd-wp
> markers. Other special markers (e.g., GUARD, POISONED) would not be caught
> early, leading to failures deeper in the swap-in logic.
>
> hpage_collapse_scan_pmd()
> `- collapse_huge_page()
> `- __collapse_huge_page_swapin() -> fails!
>
> As David suggested[1], this patch skips any such non-swap entries early.
> If a special marker is found, the scan is aborted immediately with the
> SCAN_PTE_NON_PRESENT result, as Lorenzo suggested[2], avoiding wasted
> work.
Note that I suggested to skip all non-present entries except swap
entries, which includes migration entries, hwpoisoned entries etc.
--
Cheers
David / dhildenb
next prev parent reply other threads:[~2025-09-24 10:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-24 10:02 Lance Yang
2025-09-24 10:10 ` David Hildenbrand [this message]
2025-09-24 10:17 ` Kiryl Shutsemau
2025-09-24 10:40 ` David Hildenbrand
2025-09-24 11:47 ` Lance Yang
2025-09-29 10:10 ` Lance Yang
2025-09-29 10:29 ` David Hildenbrand
2025-09-29 10:39 ` Lance Yang
2025-09-24 10:10 ` Kiryl Shutsemau
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