From: Alex Shi <alex.shi@linux.alibaba.com>
To: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, akpm@linux-foundation.org,
mgorman@techsingularity.net, tj@kernel.org, hughd@google.com,
khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com,
yang.shi@linux.alibaba.com, willy@infradead.org,
shakeelb@google.com, hannes@cmpxchg.org
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Subject: [PATCH v6 10/10] mm: revise the comments of mem_cgroup_page_lruvec
Date: Mon, 16 Dec 2019 17:26:26 +0800 [thread overview]
Message-ID: <1576488386-32544-11-git-send-email-alex.shi@linux.alibaba.com> (raw)
In-Reply-To: <1576488386-32544-1-git-send-email-alex.shi@linux.alibaba.com>
From: Johannes Weiner <hannes@cmpxchg.org>
Better document the mem_cgroup_page_lruvec() caller requirements.
Suggested-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/memcontrol.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f8e279487e1d..552de2e7da0e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1202,9 +1202,18 @@ int mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
* @page: the page
* @pgdat: pgdat of the page
*
- * This function is only safe when following the LRU page isolation
- * and putback protocol: the LRU lock must be held, and the page must
- * either be PageLRU() or the caller must have isolated/allocated it.
+ * NOTE: The returned lruvec is only stable if the calling context has
+ * the page->mem_cgroup pinned! This is accomplished by satisfying one
+ * of the following criteria:
+ *
+ * a) have the @page locked
+ * b) have an exclusive reference to @page (e.g. refcount 0)
+ * c) hold the lru_lock and "own" the PageLRU (meaning either ensure
+ * it's set, or be the one to hold the page in isolation)
+ *
+ * Otherwise, the page could be freed or moved out of the memcg,
+ * thereby releasing its reference on the memcg and potentially
+ * freeing it and its lruvecs in the process.
*/
struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat)
{
--
1.8.3.1
prev parent reply other threads:[~2019-12-16 9:27 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 9:26 [PATCH v6 00/10] per lruvec lru_lock for memcg Alex Shi
2019-12-16 9:26 ` [PATCH v6 01/10] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2019-12-16 9:26 ` [PATCH v6 02/10] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2019-12-16 12:14 ` Matthew Wilcox
2019-12-17 1:30 ` Alex Shi
2019-12-17 2:16 ` Matthew Wilcox
2019-12-17 13:11 ` Alex Shi
2019-12-16 9:26 ` [PATCH v6 03/10] mm/lru: introduce the relock_page_lruvec function Alex Shi
2019-12-16 9:26 ` [PATCH v6 04/10] mm/mlock: optimize munlock_pagevec by relocking Alex Shi
2019-12-16 9:26 ` [PATCH v6 05/10] mm/swap: only change the lru_lock iff page's lruvec is different Alex Shi
2019-12-16 9:26 ` [PATCH v6 06/10] mm/pgdat: remove pgdat lru_lock Alex Shi
2019-12-16 9:26 ` [PATCH v6 07/10] mm/lru: revise the comments of lru_lock Alex Shi
2019-12-16 9:26 ` [PATCH v6 08/10] mm/lru: debug checking for page memcg moving and lock_page_memcg Alex Shi
2019-12-16 9:26 ` [PATCH v6 09/10] mm/memcg: fold lock in lock_page_lru Alex Shi
2019-12-16 9:26 ` Alex Shi [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1576488386-32544-11-git-send-email-alex.shi@linux.alibaba.com \
--to=alex.shi@linux.alibaba.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=daniel.m.jordan@oracle.com \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=khlebnikov@yandex-team.ru \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=shakeelb@google.com \
--cc=tj@kernel.org \
--cc=willy@infradead.org \
--cc=yang.shi@linux.alibaba.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).