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From: "David Hildenbrand (Arm)" <david@kernel.org>
To: "Barry Song (Xiaomi)" <baohua@kernel.org>,
	akpm@linux-foundation.org, linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, Nanzhe Zhao <zhaonanzhe@xiaomi.com>,
	Lorenzo Stoakes <ljs@kernel.org>, Zi Yan <ziy@nvidia.com>,
	Baolin Wang <baolin.wang@linux.alibaba.com>,
	"Liam R . Howlett" <liam@infradead.org>,
	Nico Pache <npache@redhat.com>,
	Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
	Lance Yang <lance.yang@linux.dev>,
	Kairui Song <kasong@tencent.com>, Qi Zheng <qi.zheng@linux.dev>,
	Shakeel Butt <shakeel.butt@linux.dev>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>
Subject: Re: [RFC PATCH] mm: Avoiding split large folios if swap has no space
Date: Fri, 19 Jun 2026 16:01:53 +0200	[thread overview]
Message-ID: <9a194aa1-487c-4c45-b5db-00ef5190e5c1@kernel.org> (raw)
In-Reply-To: <20260618221720.71768-1-baohua@kernel.org>

On 6/19/26 00:17, Barry Song (Xiaomi) wrote:
> When swap is disabled or exhausted, swap slot allocation
> may fail during swapout, causing large folios to be split
> into small folios. The splitting is reasonable when we
> truly fail to obtain contiguous swap slots, but it is
> pointless in the no-space case.
> 
> A simple way to reproduce this is to invoke MADV_PAGEOUT on
> a system with mTHP enabled but without swap configured.

Would we ever run into that code without MADV_PAGEOUT, or is that a
MADV_PAGEOUT-special thing?

I recall that can_reclaim_anon_pages() would make vmscan skip such code, but
it's tricky.

-- 
Cheers,

David

  parent reply	other threads:[~2026-06-19 14:01 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-18 22:17 Barry Song (Xiaomi)
2026-06-18 23:46 ` Nico Pache
2026-06-19  0:59   ` Barry Song
2026-06-19 14:01 ` David Hildenbrand (Arm) [this message]
2026-06-19 23:01   ` Barry Song
2026-06-19 14:04 ` David Hildenbrand (Arm)
2026-06-20  8:10   ` Barry Song (Xiaomi)
2026-06-22  3:04     ` Baolin Wang
2026-06-22  3:36       ` Barry Song
2026-06-22  4:06         ` Baolin Wang
2026-06-22  8:58     ` David Hildenbrand (Arm)
2026-06-24 23:08       ` Barry Song
2026-06-25  7:49         ` David Hildenbrand (Arm)
2026-06-25 13:36           ` Johannes Weiner
2026-06-25 13:45             ` David Hildenbrand (Arm)
2026-06-26  6:15               ` Barry Song
2026-06-26 10:01                 ` Johannes Weiner
2026-07-07 12:42                   ` Barry Song
2026-06-19 19:17 ` Kairui Song
2026-06-19 22:42   ` Barry Song (Xiaomi)
2026-06-20  7:19     ` Kairui Song

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