linux-kernel - [PATCH 1/2] mm: fix bugs of mpol_rebind

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Date:	Thu, 22 Apr 2010 22:11:53 +0800
From:	Miao Xie <miaox@...fujitsu.com>
To:	David Rientjes <rientjes@...gle.com>,
	Lee Schermerhorn <lee.schermerhorn@...com>,
	Nick Piggin <npiggin@...e.de>, Paul Menage <menage@...gle.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-Kernel <linux-kernel@...r.kernel.org>,
	Linux-MM <linux-mm@...ck.org>
Subject: [PATCH 1/2] mm: fix bugs of mpol_rebind_nodemask()

- local variable might be an empty nodemask, so must be checked before setting
  pol->v.nodes to it.

- nodes_remap() may cause the weight of pol->v.nodes being monotonic decreasing.
  and never become large even we pass a nodemask with large weight after
  ->v.nodes become little.

this patch fixes these two problem.

Signed-off-by: Miao Xie <miaox@...fujitsu.com>
---
 mm/mempolicy.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 08f40a2..03ba9fc 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -291,12 +291,15 @@ static void mpol_rebind_nodemask(struct mempolicy *pol,
 	else if (pol->flags & MPOL_F_RELATIVE_NODES)
 		mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
 	else {
-		nodes_remap(tmp, pol->v.nodes, pol->w.cpuset_mems_allowed,
-			    *nodes);
+		tmp = *nodes;
 		pol->w.cpuset_mems_allowed = *nodes;
 	}
 
-	pol->v.nodes = tmp;
+	if (nodes_empty(tmp))
+		pol->v.nodes = *nodes;
+	else
+		pol->v.nodes = tmp;
+
 	if (!node_isset(current->il_next, tmp)) {
 		current->il_next = next_node(current->il_next, tmp);
 		if (current->il_next >= MAX_NUMNODES)
-- 
1.6.5.2


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