From: Shakeel Butt <shakeel.butt@linux.dev>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Yosry Ahmed <yosry.ahmed@linux.dev>, Zi Yan <ziy@nvidia.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Usama Arif <usama.arif@linux.dev>,
Kiryl Shutsemau <kas@kernel.org>,
Dave Chinner <david@fromorbit.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 6/7] mm: list_lru: introduce folio_memcg_list_lru_alloc()
Date: Wed, 18 Mar 2026 13:52:11 -0700 [thread overview]
Message-ID: <absQV9JTD1mj9wWb@linux.dev> (raw)
In-Reply-To: <20260318200352.1039011-7-hannes@cmpxchg.org>
On Wed, Mar 18, 2026 at 03:53:24PM -0400, Johannes Weiner wrote:
> memcg_list_lru_alloc() is called every time an object that may end up
> on the list_lru is created. It needs to quickly check if the list_lru
> heads for the memcg already exist, and allocate them when they don't.
>
> Doing this with folio objects is tricky: folio_memcg() is not stable
> and requires either RCU protection or pinning the cgroup. But it's
> desirable to make the existence check lightweight under RCU, and only
> pin the memcg when we need to allocate list_lru heads and may block.
>
> In preparation for switching the THP shrinker to list_lru, add a
> helper function for allocating list_lru heads coming from a folio.
>
> Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
next prev parent reply other threads:[~2026-03-18 20:52 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-18 19:53 [PATCH v3 0/7] mm: switch THP shrinker to list_lru Johannes Weiner
2026-03-18 19:53 ` [PATCH v3 1/7] mm: list_lru: lock_list_lru_of_memcg() cannot return NULL if !skip_empty Johannes Weiner
2026-03-18 20:12 ` Shakeel Butt
2026-03-24 11:30 ` Lorenzo Stoakes (Oracle)
2026-03-18 19:53 ` [PATCH v3 2/7] mm: list_lru: deduplicate unlock_list_lru() Johannes Weiner
2026-03-24 11:32 ` Lorenzo Stoakes (Oracle)
2026-03-18 19:53 ` [PATCH v3 3/7] mm: list_lru: move list dead check to lock_list_lru_of_memcg() Johannes Weiner
2026-03-18 20:20 ` Shakeel Butt
2026-03-24 11:34 ` Lorenzo Stoakes (Oracle)
2026-03-18 19:53 ` [PATCH v3 4/7] mm: list_lru: deduplicate lock_list_lru() Johannes Weiner
2026-03-18 20:22 ` Shakeel Butt
2026-03-24 11:36 ` Lorenzo Stoakes (Oracle)
2026-03-18 19:53 ` [PATCH v3 5/7] mm: list_lru: introduce caller locking for additions and deletions Johannes Weiner
2026-03-18 20:51 ` Shakeel Butt
2026-03-20 16:18 ` Johannes Weiner
2026-03-24 11:55 ` Lorenzo Stoakes (Oracle)
2026-03-18 19:53 ` [PATCH v3 6/7] mm: list_lru: introduce folio_memcg_list_lru_alloc() Johannes Weiner
2026-03-18 20:52 ` Shakeel Butt [this message]
2026-03-18 21:01 ` Shakeel Butt
2026-03-24 12:01 ` Lorenzo Stoakes (Oracle)
2026-03-18 19:53 ` [PATCH v3 7/7] mm: switch deferred split shrinker to list_lru Johannes Weiner
2026-03-18 20:26 ` David Hildenbrand (Arm)
2026-03-18 23:18 ` Shakeel Butt
2026-03-24 13:48 ` Lorenzo Stoakes (Oracle)
2026-03-27 7:51 ` Kairui Song
2026-03-18 21:00 ` [PATCH v3 0/7] mm: switch THP " Lorenzo Stoakes (Oracle)
2026-03-18 22:31 ` Johannes Weiner
2026-03-19 8:47 ` Lorenzo Stoakes (Oracle)
2026-03-19 8:52 ` David Hildenbrand (Arm)
2026-03-19 11:45 ` Lorenzo Stoakes (Oracle)
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