X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=kernel%2Fcpuset.c;h=0b1712dba587fdee93709798b14389f3f1d85b34;hp=ed0ff443f03640f16d0c3f68e95a5c644a948882;hb=72784134ce53b8e40deb8c9981ec52122d9f6208;hpb=b2409fb6a49d1f633a8fc488e48043da7d3fd6a7

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index ed0ff443f036..0b1712dba587 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -37,7 +37,7 @@
 #include <linux/mempolicy.h>
 #include <linux/mm.h>
 #include <linux/memory.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/mount.h>
 #include <linux/namei.h>
 #include <linux/pagemap.h>
@@ -123,6 +123,19 @@ static inline struct cpuset *task_cs(struct task_struct *task)
 			    struct cpuset, css);
 }
 
+#ifdef CONFIG_NUMA
+static inline bool task_has_mempolicy(struct task_struct *task)
+{
+	return task->mempolicy;
+}
+#else
+static inline bool task_has_mempolicy(struct task_struct *task)
+{
+	return false;
+}
+#endif
+
+
 /* bits in struct cpuset flags field */
 typedef enum {
 	CS_CPU_EXCLUSIVE,
@@ -949,7 +962,7 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
 static void cpuset_change_task_nodemask(struct task_struct *tsk,
 					nodemask_t *newmems)
 {
-	bool masks_disjoint = !nodes_intersects(*newmems, tsk->mems_allowed);
+	bool need_loop;
 
 repeat:
 	/*
@@ -962,6 +975,14 @@ repeat:
 		return;
 
 	task_lock(tsk);
+	/*
+	 * Determine if a loop is necessary if another thread is doing
+	 * get_mems_allowed().  If at least one node remains unchanged and
+	 * tsk does not have a mempolicy, then an empty nodemask will not be
+	 * possible when mems_allowed is larger than a word.
+	 */
+	need_loop = task_has_mempolicy(tsk) ||
+			!nodes_intersects(*newmems, tsk->mems_allowed);
 	nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
 	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
 
@@ -981,11 +1002,9 @@ repeat:
 
 	/*
 	 * Allocation of memory is very fast, we needn't sleep when waiting
-	 * for the read-side.  No wait is necessary, however, if at least one
-	 * node remains unchanged.
+	 * for the read-side.
 	 */
-	while (masks_disjoint &&
-			ACCESS_ONCE(tsk->mems_allowed_change_disable)) {
+	while (need_loop && ACCESS_ONCE(tsk->mems_allowed_change_disable)) {
 		task_unlock(tsk);
 		if (!task_curr(tsk))
 			yield();