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>
prev parent 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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