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cpuset: fix a regression in validating config change

PATCH In review Li Zefan 2 participants 2 messages Aug 21, 2013 cgroup

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Li Zefan

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#0 lore raw

PATCH 1/1 cpuset: fix a regression in validating config change

It's not allowed to clear masks of a cpuset if there're tasks in it, but it's broken:

  # mkdir /cgroup/sub
  # echo 0 > /cgroup/sub/cpuset.cpus
  # echo 0 > /cgroup/sub/cpuset.mems
  # echo $$ > /cgroup/sub/tasks
  # echo > /cgroup/sub/cpuset.cpus
  (should fail)

This bug was introduced by commit 88fa523bff295f1d60244a54833480b02f775152 ("cpuset: allow to move tasks to empty cpusets").

Signed-off-by Li Zefan <[email protected]>
---
 kernel/cpuset.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
kernel/cpuset.c +8 -3
index 0b5b9a3..70ab3fd 100644
@@ -425,6 +425,8 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
 	struct cgroup_subsys_state *css;
 	struct cpuset *c, *par;
 	int ret;
+	bool make_cpus_empty;
+	bool make_mems_empty;
 
 	rcu_read_lock();
 

@@ -464,12 +466,15 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
 
 	/*
 	 * Cpusets with tasks - existing or newly being attached - can't
-	 * have empty cpus_allowed or mems_allowed.
+	 * be changed to have empty cpus_allowed or mems_allowed.
 	 */
 	ret = -ENOSPC;
+	make_cpus_empty = !cpumask_empty(cur->cpus_allowed) &&
+			  cpumask_empty(trial->cpus_allowed);
+	make_mems_empty = !nodes_empty(cur->mems_allowed) &&
+			  nodes_empty(trial->mems_allowed);
 	if ((cgroup_task_count(cur->css.cgroup) || cur->attach_in_progress) &&
-	    (cpumask_empty(trial->cpus_allowed) &&
-	     nodes_empty(trial->mems_allowed)))
+	    (make_cpus_empty || make_mems_empty))
 		goto out;
 
 	ret = 0;
Signature · 1 line
1.8.0.2
maintainer
#1 lore raw

Hello, Li.

I dropped the make_*_empty variables and just put the conditionals directly inside the outer if. Please scream if I messed it up. Applied to cgroup/for-3.11-fixes.

Thanks.

------- 8< --------
From 1c09b195d37fa459844036f429a0f378e70c3db6 Mon Sep 17 00:00:00 2001
From: Li Zefan <[email protected]>
Date: Wed, 21 Aug 2013 10:22:28 +0800
Subject: [PATCH] cpuset: fix a regression in validating config change

It's not allowed to clear masks of a cpuset if there're tasks in it, but it's broken:

  # mkdir /cgroup/sub
  # echo 0 > /cgroup/sub/cpuset.cpus
  # echo 0 > /cgroup/sub/cpuset.mems
  # echo $$ > /cgroup/sub/tasks
  # echo > /cgroup/sub/cpuset.cpus
  (should fail)

This bug was introduced by commit 88fa523bff295f1d60244a54833480b02f775152 ("cpuset: allow to move tasks to empty cpusets").

tj: Dropped temp bool variables and nestes the conditionals directly.

Signed-off-by Li Zefan <[email protected]>
Signed-off-by Tejun Heo <[email protected]>
---
 kernel/cpuset.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)
kernel/cpuset.c +9 -5
index 010a008..ea1966d 100644
@@ -475,13 +475,17 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
 
 	/*
 	 * Cpusets with tasks - existing or newly being attached - can't
-	 * have empty cpus_allowed or mems_allowed.
+	 * be changed to have empty cpus_allowed or mems_allowed.
 	 */
 	ret = -ENOSPC;
-	if ((cgroup_task_count(cur->css.cgroup) || cur->attach_in_progress) &&
-	    (cpumask_empty(trial->cpus_allowed) &&
-	     nodes_empty(trial->mems_allowed)))
-		goto out;
+	if ((cgroup_task_count(cur->css.cgroup) || cur->attach_in_progress)) {
+		if (!cpumask_empty(cur->cpus_allowed) &&
+		    cpumask_empty(trial->cpus_allowed))
+			goto out;
+		if (!nodes_empty(cur->mems_allowed) &&
+		    nodes_empty(trial->mems_allowed))
+			goto out;
+	}
 
 	ret = 0;
 out:
Signature · 1 line
1.8.3.1