The patch titled Subject: slub: consider pfmemalloc_match() in get_partial_node() has been removed from the -mm tree. Its filename was slub-consider-pfmemalloc_match-in-get_partial_node.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Joonsoo Kim <js1304@xxxxxxxxx> Subject: 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@xxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Mel Gorman <mgorman@xxxxxxx> Cc: David Miller <davem@xxxxxxxxxxxxx> Cc: Chuck Lever <chuck.lever@xxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff -puN mm/slub.c~slub-consider-pfmemalloc_match-in-get_partial_node mm/slub.c --- a/mm/slub.c~slub-consider-pfmemalloc_match-in-get_partial_node +++ a/mm/slub.c @@ -1524,12 +1524,13 @@ static inline void *acquire_slab(struct } 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 kme 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 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_cac 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; _ Patches currently in -mm which might be from js1304@xxxxxxxxx are origin.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html