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-rw-r--r--include/linux/mempolicy.h8
-rw-r--r--include/uapi/linux/mempolicy.h1
-rw-r--r--mm/mempolicy.c76
3 files changed, 85 insertions, 0 deletions
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index e5ccb9ddd90e..c511e2523560 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -198,6 +198,8 @@ static inline int vma_migratable(struct vm_area_struct *vma)
return 1;
}
+extern int mpol_misplaced(struct page *, struct vm_area_struct *, unsigned long);
+
#else
struct mempolicy {};
@@ -323,5 +325,11 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol,
return 0;
}
+static inline int mpol_misplaced(struct page *page, struct vm_area_struct *vma,
+ unsigned long address)
+{
+ return -1; /* no node preference */
+}
+
#endif /* CONFIG_NUMA */
#endif
diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h
index d23dca8367cc..472de8a5d37e 100644
--- a/include/uapi/linux/mempolicy.h
+++ b/include/uapi/linux/mempolicy.h
@@ -61,6 +61,7 @@ enum mpol_rebind_step {
#define MPOL_F_SHARED (1 << 0) /* identify shared policies */
#define MPOL_F_LOCAL (1 << 1) /* preferred local allocation */
#define MPOL_F_REBINDING (1 << 2) /* identify policies in rebinding */
+#define MPOL_F_MOF (1 << 3) /* this policy wants migrate on fault */
#endif /* _UAPI_LINUX_MEMPOLICY_H */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c21e91477c4f..df1466d3d2d8 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2181,6 +2181,82 @@ static void sp_free(struct sp_node *n)
kmem_cache_free(sn_cache, n);
}
+/**
+ * mpol_misplaced - check whether current page node is valid in policy
+ *
+ * @page - page to be checked
+ * @vma - vm area where page mapped
+ * @addr - virtual address where page mapped
+ *
+ * Lookup current policy node id for vma,addr and "compare to" page's
+ * node id.
+ *
+ * Returns:
+ * -1 - not misplaced, page is in the right node
+ * node - node id where the page should be
+ *
+ * Policy determination "mimics" alloc_page_vma().
+ * Called from fault path where we know the vma and faulting address.
+ */
+int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long addr)
+{
+ struct mempolicy *pol;
+ struct zone *zone;
+ int curnid = page_to_nid(page);
+ unsigned long pgoff;
+ int polnid = -1;
+ int ret = -1;
+
+ BUG_ON(!vma);
+
+ pol = get_vma_policy(current, vma, addr);
+ if (!(pol->flags & MPOL_F_MOF))
+ goto out;
+
+ switch (pol->mode) {
+ case MPOL_INTERLEAVE:
+ BUG_ON(addr >= vma->vm_end);
+ BUG_ON(addr < vma->vm_start);
+
+ pgoff = vma->vm_pgoff;
+ pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
+ polnid = offset_il_node(pol, vma, pgoff);
+ break;
+
+ case MPOL_PREFERRED:
+ if (pol->flags & MPOL_F_LOCAL)
+ polnid = numa_node_id();
+ else
+ polnid = pol->v.preferred_node;
+ break;
+
+ case MPOL_BIND:
+ /*
+ * allows binding to multiple nodes.
+ * use current page if in policy nodemask,
+ * else select nearest allowed node, if any.
+ * If no allowed nodes, use current [!misplaced].
+ */
+ if (node_isset(curnid, pol->v.nodes))
+ goto out;
+ (void)first_zones_zonelist(
+ node_zonelist(numa_node_id(), GFP_HIGHUSER),
+ gfp_zone(GFP_HIGHUSER),
+ &pol->v.nodes, &zone);
+ polnid = zone->node;
+ break;
+
+ default:
+ BUG();
+ }
+ if (curnid != polnid)
+ ret = polnid;
+out:
+ mpol_cond_put(pol);
+
+ return ret;
+}
+
static void sp_delete(struct shared_policy *sp, struct sp_node *n)
{
pr_debug("deleting %lx-l%lx\n", n->start, n->end);