提交 7d5e3245 编写于 作者: J Johannes Weiner 提交者: Linus Torvalds

mm: memcontrol: clarify migration where old page is uncharged

Better explain re-entrant migration when compaction races with reclaim,
and also mention swapcache readahead pages as possible uncharged migration
sources.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 dfe0e773
......@@ -6157,7 +6157,12 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
if (PageCgroupUsed(pc))
return;
/* Re-entrant migration: old page already uncharged? */
/*
* Swapcache readahead pages can get migrated before being
* charged, and migration from compaction can happen to an
* uncharged page when the PFN walker finds a page that
* reclaim just put back on the LRU but has not released yet.
*/
pc = lookup_page_cgroup(oldpage);
if (!PageCgroupUsed(pc))
return;
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册