The patch titled
Subject: mm: memcontrol: do not acquire page_cgroup lock for kmem pages
has been removed from the -mm tree. Its filename was
mm-memcontrol-do-not-acquire-page_cgroup-lock-for-kmem-pages.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: memcontrol: do not acquire page_cgroup lock for kmem pages
Kmem page charging and uncharging is serialized by means of exclusive
access to the page. Do not take the page_cgroup lock and don't set
pc->flags atomically.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Acked-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 21 +++++++--------------
1 file changed, 7 insertions(+), 14 deletions(-)
diff -puN mm/memcontrol.c~mm-memcontrol-do-not-acquire-page_cgroup-lock-for-kmem-pages mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcontrol-do-not-acquire-page_cgroup-lock-for-kmem-pages
+++ a/mm/memcontrol.c
@@ -3407,12 +3407,13 @@ void __memcg_kmem_commit_charge(struct p
memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
return;
}
-
+ /*
+ * The page is freshly allocated and not visible to any
+ * outside callers yet. Set up pc non-atomically.
+ */
pc = lookup_page_cgroup(page);
- lock_page_cgroup(pc);
pc->mem_cgroup = memcg;
- SetPageCgroupUsed(pc);
- unlock_page_cgroup(pc);
+ pc->flags = PCG_USED;
}
void __memcg_kmem_uncharge_pages(struct page *page, int order)
@@ -3422,19 +3423,11 @@ void __memcg_kmem_uncharge_pages(struct
pc = lookup_page_cgroup(page);
- /*
- * Fast unlocked return. Theoretically might have changed, have to
- * check again after locking.
- */
if (!PageCgroupUsed(pc))
return;
- lock_page_cgroup(pc);
- if (PageCgroupUsed(pc)) {
- memcg = pc->mem_cgroup;
- ClearPageCgroupUsed(pc);
- }
- unlock_page_cgroup(pc);
+ memcg = pc->mem_cgroup;
+ pc->flags = 0;
/*
* We trust that only if there is a memcg associated with the page, it
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
origin.patch
mm-memcontrol-rewrite-charge-api.patch
mm-memcontrol-rewrite-uncharge-api.patch
mm-memcontrol-use-page-lists-for-uncharge-batching.patch
mm-memcontrol-use-page-lists-for-uncharge-batching-fix-hugetlb-page-lru.patch
page-cgroup-trivial-cleanup.patch
page-cgroup-get-rid-of-nr_pcg_flags.patch
memcg-remove-lookup_cgroup_page-prototype.patch
mm-memcontrol-avoid-charge-statistics-churn-during-page-migration.patch
nilfs2-integrate-sysfs-support-into-driver-fix.patch
linux-next.patch
debugging-keep-track-of-page-owners.patch
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