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authorAndi Kleen <ak@linux.intel.com>2012-06-09 02:40:03 -0700
committerBen Hutchings <ben@decadent.org.uk>2014-09-13 23:41:50 +0100
commit1a971336c449271b091fcdb3c13d535bb04bf782 (patch)
tree8a67bc12a621a1c28f2e46200f9fc2c83123f175
parent6c42026dd67496937c76d608a15faa65d2528391 (diff)
slab/mempolicy: always use local policy from interrupt context
commit e7b691b085fda913830e5280ae6f724b2a63c824 upstream. slab_node() could access current->mempolicy from interrupt context. However there's a race condition during exit where the mempolicy is first freed and then the pointer zeroed. Using this from interrupts seems bogus anyways. The interrupt will interrupt a random process and therefore get a random mempolicy. Many times, this will be idle's, which noone can change. Just disable this here and always use local for slab from interrupts. I also cleaned up the callers of slab_node a bit which always passed the same argument. I believe the original mempolicy code did that in fact, so it's likely a regression. v2: send version with correct logic v3: simplify. fix typo. Reported-by: Arun Sharma <asharma@fb.com> Cc: penberg@kernel.org Cc: cl@linux.com Signed-off-by: Andi Kleen <ak@linux.intel.com> [tdmackey@twitter.com: Rework control flow based on feedback from cl@linux.com, fix logic, and cleanup current task_struct reference] Acked-by: David Rientjes <rientjes@google.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: David Mackey <tdmackey@twitter.com> Signed-off-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r--include/linux/mempolicy.h2
-rw-r--r--mm/mempolicy.c8
-rw-r--r--mm/slab.c4
-rw-r--r--mm/slub.c2
4 files changed, 11 insertions, 5 deletions
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index f85c5ab2cc54..11670e3747d9 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -205,7 +205,7 @@ extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
extern bool init_nodemask_of_mempolicy(nodemask_t *mask);
extern bool mempolicy_nodemask_intersects(struct task_struct *tsk,
const nodemask_t *mask);
-extern unsigned slab_node(struct mempolicy *policy);
+extern unsigned slab_node(void);
extern enum zone_type policy_zone;
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c9f7e6f1d1d9..a72fa33b31cd 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1601,8 +1601,14 @@ static unsigned interleave_nodes(struct mempolicy *policy)
* task can change it's policy. The system default policy requires no
* such protection.
*/
-unsigned slab_node(struct mempolicy *policy)
+unsigned slab_node(void)
{
+ struct mempolicy *policy;
+
+ if (in_interrupt())
+ return numa_node_id();
+
+ policy = current->mempolicy;
if (!policy || policy->flags & MPOL_F_LOCAL)
return numa_node_id();
diff --git a/mm/slab.c b/mm/slab.c
index 4c3b6719eccc..aea5e42c67d8 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3270,7 +3270,7 @@ static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
nid_alloc = cpuset_slab_spread_node();
else if (current->mempolicy)
- nid_alloc = slab_node(current->mempolicy);
+ nid_alloc = slab_node();
if (nid_alloc != nid_here)
return ____cache_alloc_node(cachep, flags, nid_alloc);
return NULL;
@@ -3302,7 +3302,7 @@ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
retry_cpuset:
cpuset_mems_cookie = get_mems_allowed();
- zonelist = node_zonelist(slab_node(current->mempolicy), flags);
+ zonelist = node_zonelist(slab_node(), flags);
retry:
/*
diff --git a/mm/slub.c b/mm/slub.c
index fc719f7dd407..6a4c2fb83839 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1608,7 +1608,7 @@ static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags,
do {
cpuset_mems_cookie = get_mems_allowed();
- zonelist = node_zonelist(slab_node(current->mempolicy), flags);
+ zonelist = node_zonelist(slab_node(), flags);
for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
struct kmem_cache_node *n;