diff options
| author | Andi Kleen <ak@linux.intel.com> | 2012-06-09 02:40:03 -0700 |
|---|---|---|
| committer | Zefan Li <lizefan@huawei.com> | 2014-09-25 11:49:17 +0800 |
| commit | 69db2d4044cc494b03bad01b2e106f7324ef3fdf (patch) | |
| tree | ce09bfaf1099abfdd23e71c52652fde1e8ba35a3 /mm/mempolicy.c | |
| parent | ab22539512b325240dac92e92bbaf1d9aebaa2e5 (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: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'mm/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 5cec36b6e838..87a43cce8d59 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1609,8 +1609,14 @@ 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(); |