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Subject[PATCH v4 04/13] mm/mempolicy: allow preferred code to take a nodemask
Date
From: Dave Hansen <dave.hansen@linux.intel.com>

Create a helper function (mpol_new_preferred_many()) which is usable
both by the old, single-node MPOL_PREFERRED and the new
MPOL_PREFERRED_MANY.

Enforce the old single-node MPOL_PREFERRED behavior in the "new"
version of mpol_new_preferred() which calls mpol_new_preferred_many().

v3:
* fix a stack overflow caused by emty nodemask (Feng)

Link: https://lore.kernel.org/r/20200630212517.308045-5-ben.widawsky@intel.com
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
---
mm/mempolicy.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 1228d8e..6fb2cab 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -203,17 +203,34 @@ static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
return 0;
}

-static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
+static int mpol_new_preferred_many(struct mempolicy *pol,
+ const nodemask_t *nodes)
{
if (!nodes)
pol->flags |= MPOL_F_LOCAL; /* local allocation */
else if (nodes_empty(*nodes))
return -EINVAL; /* no allowed nodes */
else
- pol->v.preferred_nodes = nodemask_of_node(first_node(*nodes));
+ pol->v.preferred_nodes = *nodes;
return 0;
}

+static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
+{
+ if (nodes) {
+ /* MPOL_PREFERRED can only take a single node: */
+ nodemask_t tmp;
+
+ if (nodes_empty(*nodes))
+ return -EINVAL;
+
+ tmp = nodemask_of_node(first_node(*nodes));
+ return mpol_new_preferred_many(pol, &tmp);
+ }
+
+ return mpol_new_preferred_many(pol, NULL);
+}
+
static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
{
if (nodes_empty(*nodes))
--
2.7.4
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