linux-kernel - [PATCH 04/12] mm/mempolicy: allow preferred code to take a nodemask

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Date:   Fri, 30 Oct 2020 12:02:30 -0700
From:   Ben Widawsky <ben.widawsky@...el.com>
To:     linux-mm <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Michal Hocko <mhocko@...nel.org>,
        Ben Widawsky <ben.widawsky@...el.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 04/12] mm/mempolicy: allow preferred code to take a nodemask

From: Dave Hansen <dave.hansen@...ux.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().

Link: https://lore.kernel.org/r/20200630212517.308045-5-ben.widawsky@intel.com
Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>
---
 mm/mempolicy.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 21a6f80f91a9..b1b43e511d6f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -203,17 +203,30 @@ 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 = 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))
-- 
2.29.2