The patch titled
Subject: mm/list_lru.c: fix list_lru_count_node() to be race free
has been added to the -mm tree. Its filename is
mm-list_lruc-fix-list_lru_count_node-to-be-race-free.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-list_lruc-fix-list_lru_count_node-to-be-race-free.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-list_lruc-fix-list_lru_count_node-to-be-race-free.patch
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------------------------------------------------------
From: Sahitya Tummala <stummala@xxxxxxxxxxxxxx>
Subject: mm/list_lru.c: fix list_lru_count_node() to be race free
list_lru_count_node() iterates over all memcgs to get the total number of
entries on the node but it can race with memcg_drain_all_list_lrus(),
which migrates the entries from a dead cgroup to another. This can return
incorrect number of entries from list_lru_count_node().
Fix this by keeping track of entries per node and simply return it in
list_lru_count_node().
Link: http://lkml.kernel.org/r/1498707555-30525-1-git-send-email-stummala@xxxxxxxxxxxxxx
Signed-off-by: Sahitya Tummala <stummala@xxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Alexander Polakov <apolyakov@xxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/list_lru.h | 1 +
mm/list_lru.c | 14 ++++++--------
2 files changed, 7 insertions(+), 8 deletions(-)
diff -puN include/linux/list_lru.h~mm-list_lruc-fix-list_lru_count_node-to-be-race-free include/linux/list_lru.h
--- a/include/linux/list_lru.h~mm-list_lruc-fix-list_lru_count_node-to-be-race-free
+++ a/include/linux/list_lru.h
@@ -44,6 +44,7 @@ struct list_lru_node {
/* for cgroup aware lrus points to per cgroup lists, otherwise NULL */
struct list_lru_memcg *memcg_lrus;
#endif
+ long nr_items;
} ____cacheline_aligned_in_smp;
struct list_lru {
diff -puN mm/list_lru.c~mm-list_lruc-fix-list_lru_count_node-to-be-race-free mm/list_lru.c
--- a/mm/list_lru.c~mm-list_lruc-fix-list_lru_count_node-to-be-race-free
+++ a/mm/list_lru.c
@@ -117,6 +117,7 @@ bool list_lru_add(struct list_lru *lru,
l = list_lru_from_kmem(nlru, item);
list_add_tail(item, &l->list);
l->nr_items++;
+ nlru->nr_items++;
spin_unlock(&nlru->lock);
return true;
}
@@ -136,6 +137,7 @@ bool list_lru_del(struct list_lru *lru,
l = list_lru_from_kmem(nlru, item);
list_del_init(item);
l->nr_items--;
+ nlru->nr_items--;
spin_unlock(&nlru->lock);
return true;
}
@@ -183,15 +185,10 @@ EXPORT_SYMBOL_GPL(list_lru_count_one);
unsigned long list_lru_count_node(struct list_lru *lru, int nid)
{
- long count = 0;
- int memcg_idx;
+ struct list_lru_node *nlru;
- count += __list_lru_count_one(lru, nid, -1);
- if (list_lru_memcg_aware(lru)) {
- for_each_memcg_cache_index(memcg_idx)
- count += __list_lru_count_one(lru, nid, memcg_idx);
- }
- return count;
+ nlru = &lru->node[nid];
+ return nlru->nr_items;
}
EXPORT_SYMBOL_GPL(list_lru_count_node);
@@ -226,6 +223,7 @@ restart:
assert_spin_locked(&nlru->lock);
case LRU_REMOVED:
isolated++;
+ nlru->nr_items--;
/*
* If the lru lock has been dropped, our list
* traversal is now invalid and so we have to
_
Patches currently in -mm which might be from stummala@xxxxxxxxxxxxxx are
mm-list_lruc-use-cond_resched_lock-for-nlru-lock.patch
mm-list_lruc-fix-list_lru_count_node-to-be-race-free.patch
fs-dcachec-fix-spin-lockup-issue-on-nlru-lock.patch
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