[patch 2/2] slub: enforce cpuset restrictions for cpu slabs

[David Rientjes]

Slab allocations should respect cpuset hardwall restrictions.  Otherwise,
it is possible for tasks in a cpuset to fill slabs allocated on mems
assigned to a disjoint cpuset.

When an allocation is attempted for a cpu slab that resides on a node that
is not allowed by a task's cpuset, an appropriate partial slab or new slab
is allocated.

If an allocation is intended for a particular node that the task does not
have access to because of its cpuset, an allowed partial slab is used
instead of failing.

Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
 mm/slub.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1353,6 +1353,8 @@ static struct page *get_partial(struct kmem_cache *s, gfp_t flags, int node)
 	struct page *page;
 	int searchnode = (node == -1) ? numa_node_id() : node;
 
+	if (!cpuset_node_allowed_hardwall(searchnode, flags))
+		searchnode = cpuset_mem_spread_node();
 	page = get_partial_node(get_node(s, searchnode));
 	if (page || (flags & __GFP_THISNODE))
 		return page;
@@ -1477,13 +1479,13 @@ static void flush_all(struct kmem_cache *s)
  * Check if the objects in a per cpu structure fit numa
  * locality expectations.
  */
-static inline int node_match(struct kmem_cache_cpu *c, int node)
+static inline int node_match(struct kmem_cache_cpu *c, int node, gfp_t gfpflags)
 {
 #ifdef CONFIG_NUMA
 	if (node != -1 && c->node != node)
 		return 0;
 #endif
-	return 1;
+	return cpuset_node_allowed_hardwall(c->node, gfpflags);
 }
 
 /*
@@ -1517,7 +1519,7 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 		goto new_slab;
 
 	slab_lock(c->page);
-	if (unlikely(!node_match(c, node)))
+	if (unlikely(!node_match(c, node, gfpflags)))
 		goto another_slab;
 
 	stat(c, ALLOC_REFILL);
@@ -1604,7 +1606,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
 	local_irq_save(flags);
 	c = get_cpu_slab(s, smp_processor_id());
 	objsize = c->objsize;
-	if (unlikely(!c->freelist || !node_match(c, node)))
+	if (unlikely(!c->freelist || !node_match(c, node, gfpflags)))
 
 		object = __slab_alloc(s, gfpflags, node, addr, c);
 
--
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