Commit fd603ae1 authored by Muchun Song's avatar Muchun Song Committed by Andrew Morton
Browse files

mm: thp: replace folio_memcg() with folio_memcg_charged() 

Patch series "reparent the THP split queue", v6.

In the future, we will reparent LRU folios during memcg offline to
eliminate dying memory cgroups, which requires reparenting the THP split
queue to its parent memcg.

Similar to list_lru, the split queue is relatively independent and does
not need to be reparented along with objcg and LRU folios (holding objcg
lock and lru lock).  Therefore, we can apply the same mechanism as
list_lru to reparent the split queue first when memcg is offine.

The first three patches in this series are separated from the series
"Eliminate Dying Memory Cgroup" [1], mainly to do some cleanup and
preparatory work.

The last patch reparents the THP split queue to its parent memcg during
memcg offline.


This patch (of 4):

folio_memcg_charged() is intended for use when the user is unconcerned
about the returned memcg pointer.  It is more efficient than
folio_memcg().  Therefore, replace folio_memcg() with
folio_memcg_charged().

Link: https://lkml.kernel.org/r/56624d537520e33e5a6b3755238b3dfb959a52ee.1762762324.git.zhengqi.arch@bytedance.com
Link: https://lore.kernel.org/all/20250415024532.26632-1-songmuchun@bytedance.com/

 [1]
Signed-off-by: default avatarMuchun Song <songmuchun@bytedance.com>
Signed-off-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: default avatarHarry Yoo <harry.yoo@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a3a3e215

mm/huge_memory.c

+1 −1
Original line number Diff line number Diff line
@@ -4127,7 +4127,7 @@ bool __folio_unqueue_deferred_split(struct folio *folio) 
	bool unqueued = false;



	WARN_ON_ONCE(folio_ref_count(folio));

	WARN_ON_ONCE(!mem_cgroup_disabled() && !folio_memcg(folio));

	WARN_ON_ONCE(!mem_cgroup_disabled() && !folio_memcg_charged(folio));



	ds_queue = get_deferred_split_queue(folio);

	spin_lock_irqsave(&ds_queue->split_queue_lock, flags);