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From: Lance Yang <lance.yang@linux.dev>
To: Kiryl Shutsemau <kirill@shutemov.name>
Cc: ziy@nvidia.com, kasong@tencent.com, usama.arif@linux.dev,
	hannes@cmpxchg.org, ljs@kernel.org, hughd@google.com,
	baolin.wang@linux.alibaba.com, baohua@kernel.org,
	liam@infradead.org, nico.pache@linux.dev, dev.jain@arm.com,
	david@kernel.org, akpm@linux-foundation.org,
	ryan.roberts@arm.com, balbirs@nvidia.com, kas@kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] mm/huge_memory: dequeue the deferred split after the split freeze
Date: Mon, 31 Aug 2026 19:34:58 +0800	[thread overview]
Message-ID: <75ac2253-5d64-49e0-b090-b385e864c925@linux.dev> (raw)
In-Reply-To: <20260831091514.1879786-3-kirill@shutemov.name>



On 2026/8/31 17:15, Kiryl Shutsemau wrote:
> From: "Kiryl Shutsemau (Meta)" <kas@kernel.org>
> 
> __folio_freeze_and_split_unmapped() takes the deferred split list_lru lock
> across the freeze. It is only there to stop deferred_split_scan() from
> touching the folio under split.
> 
> With deferred_split_isolate() fixed, the workaround can be dropped.
> 
> Unqueue the folio after folio_ref_freeze(), the way
> __folio_migrate_mapping() does: folio_unqueue_deferred_split() needs a
> zero refcount and a memcg still set, and both hold there.
> 
> If the split is called from deferred_split_scan(), the unqueue is a
> no-op -- the folio is already removed from the list. But
> PG_partially_mapped is still set, so it has to be cleared here or
> MTHP_STAT_NR_ANON_PARTIALLY_MAPPED never comes back down.
> 
> Assisted-by: Claude-Code:claude-opus-5
> Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
> Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> ---

Nothing jumped out at me :)

Reviewed-by: Lance Yang <lance.yang@linux.dev>


      reply	other threads:[~2026-08-31 11:35 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-31  9:15 [PATCH v2 0/2] Fix deferred_split_isolate() and drop the split workaround Kiryl Shutsemau
2026-08-31  9:15 ` [PATCH v2 1/2] mm/huge_memory: do not touch frozen folios in deferred_split_isolate() Kiryl Shutsemau
2026-08-31 11:16   ` Lance Yang
2026-08-31 11:23   ` Usama Arif
2026-09-01  1:38   ` Baolin Wang
2026-08-31  9:15 ` [PATCH v2 2/2] mm/huge_memory: dequeue the deferred split after the split freeze Kiryl Shutsemau
2026-08-31 11:34   ` Lance Yang [this message]

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