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| author | Joonsoo Kim <iamjoonsoo.kim@lge.com> | 2013-01-21 17:01:25 +0900 |
|---|---|---|
| committer | Pekka Enberg <penberg@kernel.org> | 2013-04-02 09:42:10 +0300 |
| commit | 633b076464da52b3c7bf0f62932fbfc0ea23d8b3 (patch) | |
| tree | 546927d08f30ea3049051b89a55b7c7a56937f7f /mm/slub.c | |
| parent | 7d557b3cb69398d83ceabad9cf147c93a3aa97fd (diff) | |
| download | lwn-633b076464da52b3c7bf0f62932fbfc0ea23d8b3.tar.gz lwn-633b076464da52b3c7bf0f62932fbfc0ea23d8b3.zip | |
slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Diffstat (limited to 'mm/slub.c')
| -rw-r--r-- | mm/slub.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/mm/slub.c b/mm/slub.c index aa0728daf8bb..8f73593d4f21 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1493,7 +1493,7 @@ static inline void remove_partial(struct kmem_cache_node *n, */ static inline void *acquire_slab(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page, - int mode) + int mode, int *objects) { void *freelist; unsigned long counters; @@ -1507,6 +1507,7 @@ static inline void *acquire_slab(struct kmem_cache *s, freelist = page->freelist; counters = page->counters; new.counters = counters; + *objects = new.objects - new.inuse; if (mode) { new.inuse = page->objects; new.freelist = NULL; @@ -1528,7 +1529,7 @@ static inline void *acquire_slab(struct kmem_cache *s, return freelist; } -static int put_cpu_partial(struct kmem_cache *s, struct page *page, int drain); +static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain); static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags); /* @@ -1539,6 +1540,8 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, { struct page *page, *page2; void *object = NULL; + int available = 0; + int objects; /* * Racy check. If we mistakenly see no partial slabs then we @@ -1552,22 +1555,21 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, spin_lock(&n->list_lock); list_for_each_entry_safe(page, page2, &n->partial, lru) { void *t; - int available; if (!pfmemalloc_match(page, flags)) continue; - t = acquire_slab(s, n, page, object == NULL); + t = acquire_slab(s, n, page, object == NULL, &objects); if (!t) break; + available += objects; if (!object) { c->page = page; stat(s, ALLOC_FROM_PARTIAL); object = t; - available = page->objects - page->inuse; } else { - available = put_cpu_partial(s, page, 0); + put_cpu_partial(s, page, 0); stat(s, CPU_PARTIAL_NODE); } if (kmem_cache_debug(s) || available > s->cpu_partial / 2) @@ -1946,7 +1948,7 @@ static void unfreeze_partials(struct kmem_cache *s, * If we did not find a slot then simply move all the partials to the * per node partial list. */ -static int put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) +static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) { struct page *oldpage; int pages; @@ -1984,7 +1986,6 @@ static int put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) page->next = oldpage; } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage); - return pobjects; } static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) |