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-rw-r--r--mm/mempolicy.c44
1 files changed, 44 insertions, 0 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5bc0a96beb5..8a73708d59b 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1712,6 +1712,50 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask)
}
#endif
+/*
+ * mempolicy_nodemask_intersects
+ *
+ * If tsk's mempolicy is "default" [NULL], return 'true' to indicate default
+ * policy. Otherwise, check for intersection between mask and the policy
+ * nodemask for 'bind' or 'interleave' policy. For 'perferred' or 'local'
+ * policy, always return true since it may allocate elsewhere on fallback.
+ *
+ * Takes task_lock(tsk) to prevent freeing of its mempolicy.
+ */
+bool mempolicy_nodemask_intersects(struct task_struct *tsk,
+ const nodemask_t *mask)
+{
+ struct mempolicy *mempolicy;
+ bool ret = true;
+
+ if (!mask)
+ return ret;
+ task_lock(tsk);
+ mempolicy = tsk->mempolicy;
+ if (!mempolicy)
+ goto out;
+
+ switch (mempolicy->mode) {
+ case MPOL_PREFERRED:
+ /*
+ * MPOL_PREFERRED and MPOL_F_LOCAL are only preferred nodes to
+ * allocate from, they may fallback to other nodes when oom.
+ * Thus, it's possible for tsk to have allocated memory from
+ * nodes in mask.
+ */
+ break;
+ case MPOL_BIND:
+ case MPOL_INTERLEAVE:
+ ret = nodes_intersects(mempolicy->v.nodes, *mask);
+ break;
+ default:
+ BUG();
+ }
+out:
+ task_unlock(tsk);
+ return ret;
+}
+
/* Allocate a page in interleaved policy.
Own path because it needs to do special accounting. */
static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,