[091/192] mm: memcontrol: move obj_cgroup_uncharge_pages() out of css_set_lock

Commit Message

Andrew Morton June 29, 2021, 2:38 a.m. UTC

From: Muchun Song <[e-mail]>
Subject: mm: memcontrol: move obj_cgroup_uncharge_pages() out of css_set_lock

The css_set_lock is used to guard the list of inherited objcgs.  So there
is no need to uncharge kernel memory under css_set_lock.  Just move it out
of the lock.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Muchun Song <[e-mail]>
Reviewed-by: Shakeel Butt <[e-mail]>
Acked-by: Roman Gushchin <[e-mail]>
Acked-by: Johannes Weiner <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Vladimir Davydov <[e-mail]>
Cc: Xiongchun Duan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memcontrol.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Patch

--- a/mm/memcontrol.c~mm-memcontrol-move-obj_cgroup_uncharge_pages-out-of-css_set_lock
+++ a/mm/memcontrol.c
@@ -289,9 +289,10 @@  static void obj_cgroup_release(struct pe
 	WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1));
 	nr_pages = nr_bytes >> PAGE_SHIFT;
 
-	spin_lock_irqsave(&css_set_lock, flags);
 	if (nr_pages)
 		obj_cgroup_uncharge_pages(objcg, nr_pages);
+
+	spin_lock_irqsave(&css_set_lock, flags);
 	list_del(&objcg->list);
 	spin_unlock_irqrestore(&css_set_lock, flags);