diff options
| author | Joonsoo Kim <js1304@gmail.com> | 2012-09-17 14:09:09 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-09-17 15:00:38 -0700 |
| commit | 8ba00bb68a067c221cc3ea3a0293e8fcbdcb7ba1 (patch) | |
| tree | 6642f9819b79c51891d7f829c5cf1f384ffc6cc5 /mm/slub.c | |
| parent | d014dc2ed4fae84cb92509416c8bfc9078d4f0d9 (diff) | |
slub: consider pfmemalloc_match() in get_partial_node()
get_partial() is currently not checking pfmemalloc_match() meaning that
it is possible for pfmemalloc pages to leak to non-pfmemalloc users.
This is a problem in the following situation. Assume that there is a
request from normal allocation and there are no objects in the per-cpu
cache and no node-partial slab.
In this case, slab_alloc enters the slow path and new_slab_objects() is
called which may return a PFMEMALLOC page. As the current user is not
allowed to access PFMEMALLOC page, deactivate_slab() is called
([5091b74a: mm: slub: optimise the SLUB fast path to avoid pfmemalloc
checks]) and returns an object from PFMEMALLOC page.
Next time, when we get another request from normal allocation,
slab_alloc() enters the slow-path and calls new_slab_objects(). In
new_slab_objects(), we call get_partial() and get a partial slab which
was just deactivated but is a pfmemalloc page. We extract one object
from it and re-deactivate.
"deactivate -> re-get in get_partial -> re-deactivate" occures repeatedly.
As a result, access to PFMEMALLOC page is not properly restricted and it
can cause a performance degradation due to frequent deactivation.
deactivation frequently.
This patch changes get_partial_node() to take pfmemalloc_match() into
account and prevents the "deactivate -> re-get in get_partial()
scenario. Instead, new_slab() is called.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slub.c')
| -rw-r--r-- | mm/slub.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/mm/slub.c b/mm/slub.c index 8f78e257703..2fdd96f9e99 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1524,12 +1524,13 @@ static inline void *acquire_slab(struct kmem_cache *s, } static int put_cpu_partial(struct kmem_cache *s, struct page *page, int drain); +static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags); /* * Try to allocate a partial slab from a specific node. */ -static void *get_partial_node(struct kmem_cache *s, - struct kmem_cache_node *n, struct kmem_cache_cpu *c) +static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, + struct kmem_cache_cpu *c, gfp_t flags) { struct page *page, *page2; void *object = NULL; @@ -1545,9 +1546,13 @@ static void *get_partial_node(struct kmem_cache *s, spin_lock(&n->list_lock); list_for_each_entry_safe(page, page2, &n->partial, lru) { - void *t = acquire_slab(s, n, page, object == NULL); + void *t; int available; + if (!pfmemalloc_match(page, flags)) + continue; + + t = acquire_slab(s, n, page, object == NULL); if (!t) break; @@ -1614,7 +1619,7 @@ static void *get_any_partial(struct kmem_cache *s, gfp_t flags, if (n && cpuset_zone_allowed_hardwall(zone, flags) && n->nr_partial > s->min_partial) { - object = get_partial_node(s, n, c); + object = get_partial_node(s, n, c, flags); if (object) { /* * Return the object even if @@ -1643,7 +1648,7 @@ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node, void *object; int searchnode = (node == NUMA_NO_NODE) ? numa_node_id() : node; - object = get_partial_node(s, get_node(s, searchnode), c); + object = get_partial_node(s, get_node(s, searchnode), c, flags); if (object || node != NUMA_NO_NODE) return object; |