From: Lance Yang <lance.yang@linux.dev>
To: kas@kernel.org
Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org,
ziy@nvidia.com, baolin.wang@linux.alibaba.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@meta.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, vbabka@kernel.org,
jannh@google.com
Subject: Re: [PATCH v5 1/9] mm/khugepaged: drop redundant mm_struct pin in madvise_collapse()
Date: Thu, 15 Oct 2026 12:34:04 +0800 [thread overview]
Message-ID: <20261015043404.57470-1-lance.yang@linux.dev> (raw)
In-Reply-To: <20261014171145.3292736-2-kas@kernel.org>
On Wed, Oct 14, 2026 at 06:11:34PM +0100, Kiryl Shutsemau (Meta) wrote:
>madvise_collapse() holds an mmgrab() reference across its work. It is
>redundant. Every caller already holds mm_users:
>
> - madvise(2) works on current->mm, which lives as long as the task is in
> the syscall;
> - process_madvise(2) reaches a remote mm through mm_access(), which takes
> an mm_users reference and holds it until the syscall returns;
> - io_uring passes current->mm;
> - DAMON takes one with get_task_mm() and drops it after the call.
>
>Drop the mmgrab()/mmdrop() pair.
>
>Assisted-by: LLM
>Acked-by: David Hildenbrand (Arm) <david@kernel.org>
>Reviewed-by: Zi Yan <ziy@nvidia.com>
>Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
>---
Reviewed-by: Lance Yang <lance.yang@linux.dev>
next prev parent reply other threads:[~2026-10-15 4:34 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-14 17:11 [PATCH v5 0/9] mm/collapse: separate a collapse from its callers Kiryl Shutsemau (Meta)
2026-10-14 17:11 ` [PATCH v5 1/9] mm/khugepaged: drop redundant mm_struct pin in madvise_collapse() Kiryl Shutsemau (Meta)
2026-10-15 4:34 ` Lance Yang [this message]
2026-10-14 17:11 ` [PATCH v5 2/9] mm/khugepaged: count collapses where khugepaged makes them Kiryl Shutsemau (Meta)
2026-10-15 4:36 ` Lance Yang
2026-10-14 17:11 ` [PATCH v5 3/9] mm/khugepaged: rename mthp_present_ptes bitmap to eligible_ptes Kiryl Shutsemau (Meta)
2026-10-15 4:38 ` Lance Yang
2026-10-14 17:11 ` [PATCH v5 4/9] mm/collapse: add collapse.h for the collapse interface Kiryl Shutsemau (Meta)
2026-10-15 4:41 ` Lance Yang
2026-10-14 17:11 ` [PATCH v5 5/9] mm/collapse: state what a collapse may do in the policy Kiryl Shutsemau (Meta)
2026-10-15 4:44 ` Lance Yang
2026-10-14 17:11 ` [PATCH v5 6/9] mm/collapse: drop the collapse_possible() wrapper Kiryl Shutsemau (Meta)
2026-10-15 4:45 ` Lance Yang
2026-10-14 17:11 ` [PATCH v5 7/9] mm/collapse: name the per-table scan reset for what it resets Kiryl Shutsemau (Meta)
2026-10-15 4:46 ` Lance Yang
2026-10-14 17:11 ` [PATCH v5 8/9] mm/collapse: call collapse_file() from collapse_single_pmd() Kiryl Shutsemau (Meta)
2026-10-15 5:39 ` Lance Yang
2026-10-15 7:21 ` Baolin Wang
2026-10-14 17:11 ` [PATCH v5 9/9] mm/collapse: separate scanning a PTE table from collapsing it Kiryl Shutsemau (Meta)
2026-10-15 5:43 ` Lance Yang
2026-10-14 21:16 ` [PATCH v5 0/9] mm/collapse: separate a collapse from its callers Andrew Morton
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