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-rw-r--r--mm/mempolicy.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e9fc1c1ae66..c6c61ea6bb8 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -591,16 +591,29 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags,
nodemask_t *nodes)
{
struct mempolicy *new;
+ struct mm_struct *mm = current->mm;
new = mpol_new(mode, flags, nodes);
if (IS_ERR(new))
return PTR_ERR(new);
+
+ /*
+ * prevent changing our mempolicy while show_numa_maps()
+ * is using it.
+ * Note: do_set_mempolicy() can be called at init time
+ * with no 'mm'.
+ */
+ if (mm)
+ down_write(&mm->mmap_sem);
mpol_put(current->mempolicy);
current->mempolicy = new;
mpol_set_task_struct_flag();
if (new && new->policy == MPOL_INTERLEAVE &&
nodes_weight(new->v.nodes))
current->il_next = first_node(new->v.nodes);
+ if (mm)
+ up_write(&mm->mmap_sem);
+
return 0;
}