From: js1304@gmail.com
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>, Hugh Dickins <hughd@google.com>,
Minchan Kim <minchan@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
kernel-team@lge.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: [PATCH v3 6/9] mm/workingset: handle the page without memcg
Date: Tue, 17 Mar 2020 14:41:54 +0900 [thread overview]
Message-ID: <1584423717-3440-7-git-send-email-iamjoonsoo.kim@lge.com> (raw)
In-Reply-To: <1584423717-3440-1-git-send-email-iamjoonsoo.kim@lge.com>
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
When implementing workingset detection for anonymous page, I found
some swapcache pages with NULL memcg. From the code reading, I found
two reasons.
One is the case that swap-in readahead happens. The other is the
corner case related to the shmem cache. These two problems should be
fixed, but, it's not straight-forward to fix. For example, when swap-off,
all swapped-out pages are read into swapcache. In this case, who's the
owner of the swapcache page?
Since this problem doesn't look trivial, I decide to leave the issue and
handles this corner case on the place where the error occurs.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
mm/workingset.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/workingset.c b/mm/workingset.c
index a9f474a..8d2e83a 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -257,6 +257,10 @@ void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg)
VM_BUG_ON_PAGE(page_count(page), page);
VM_BUG_ON_PAGE(!PageLocked(page), page);
+ /* page_memcg() can be NULL if swap-in readahead happens */
+ if (!page_memcg(page))
+ return NULL;
+
advance_inactive_age(page_memcg(page), pgdat, is_file);
lruvec = mem_cgroup_lruvec(target_memcg, pgdat);
--
2.7.4
next prev parent reply other threads:[~2020-03-17 5:42 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 5:41 [PATCH v3 0/9] workingset protection/detection on the anonymous LRU list js1304
2020-03-17 5:41 ` [PATCH v3 1/9] mm/vmscan: make active/inactive ratio as 1:1 for anon lru js1304
2020-03-18 17:45 ` Johannes Weiner
2020-03-17 5:41 ` [PATCH v3 2/9] mm/vmscan: protect the workingset on anonymous LRU js1304
2020-03-18 17:51 ` Johannes Weiner
2020-03-19 4:01 ` Joonsoo Kim
2020-03-17 5:41 ` [PATCH v3 3/9] mm/workingset: extend the workingset detection for anon LRU js1304
2020-03-18 18:06 ` Johannes Weiner
2020-03-19 4:13 ` Joonsoo Kim
2020-03-17 5:41 ` [PATCH v3 4/9] mm/swapcache: support to handle the value in swapcache js1304
2020-03-18 18:33 ` Johannes Weiner
2020-03-19 6:01 ` Joonsoo Kim
2020-03-17 5:41 ` [PATCH v3 5/9] mm/workingset: use the node counter if memcg is the root memcg js1304
2020-03-18 19:18 ` Johannes Weiner
2020-03-19 6:20 ` Joonsoo Kim
2020-03-17 5:41 ` js1304 [this message]
2020-03-18 19:59 ` [PATCH v3 6/9] mm/workingset: handle the page without memcg Johannes Weiner
2020-03-19 8:31 ` Joonsoo Kim
2020-03-17 5:41 ` [PATCH v3 7/9] mm/swap: implement workingset detection for anonymous LRU js1304
2020-03-17 5:41 ` [PATCH v3 8/9] mm/vmscan: restore active/inactive ratio " js1304
2020-03-17 5:41 ` [PATCH v3 9/9] mm/swap: count a new anonymous page as a reclaim_state's rotate js1304
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