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authorAndi Kleen <ak@linux.intel.com>2012-06-09 02:40:03 -0700
committerPekka Enberg <penberg@kernel.org>2012-06-20 10:01:04 +0300
commite7b691b085fda913830e5280ae6f724b2a63c824 (patch)
tree9fbd380538f1c3fd5e36c5beeac35041351baf40 /mm/mempolicy.c
parent8c138bc00925521c4e764269db3a903bd2a51592 (diff)
downloadlinux-e7b691b085fda913830e5280ae6f724b2a63c824.tar.gz
slab/mempolicy: always use local policy from interrupt context
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>
Diffstat (limited to 'mm/mempolicy.c')
-rw-r--r--mm/mempolicy.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index f15c1b24ca1..cb0b230aa3f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1602,8 +1602,14 @@ 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();