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| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2009-01-08 03:08:39 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-08 17:31:11 +0100 |
| commit | 13337714f3b0307dc7f75ef5d83ecf0db2abbd65 (patch) | |
| tree | f76dd8961b9287b25e2ea24d2d34fecc52d2c8a0 /kernel/cpuset.c | |
| parent | cgroups: add css_tryget() (diff) | |
| download | linux-13337714f3b0307dc7f75ef5d83ecf0db2abbd65.tar.xz linux-13337714f3b0307dc7f75ef5d83ecf0db2abbd65.zip | |
cpuset: rcu_read_lock() to protect task_cs()
task_cs() calls task_subsys_state().
We must use rcu_read_lock() to protect cgroup_subsys_state().
It's correct that top_cpuset is never freed, but cgroup_subsys_state()
accesses css_set, this css_set maybe freed when task_cs() called.
We use use rcu_read_lock() to protect it.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 345ace5117de..a841b5c01ef9 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -375,14 +375,9 @@ void cpuset_update_task_memory_state(void) struct task_struct *tsk = current; struct cpuset *cs; - if (task_cs(tsk) == &top_cpuset) { - /* Don't need rcu for top_cpuset. It's never freed. */ - my_cpusets_mem_gen = top_cpuset.mems_generation; - } else { - rcu_read_lock(); - my_cpusets_mem_gen = task_cs(tsk)->mems_generation; - rcu_read_unlock(); - } + rcu_read_lock(); + my_cpusets_mem_gen = task_cs(tsk)->mems_generation; + rcu_read_unlock(); if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) { mutex_lock(&callback_mutex); |