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authorKirill Tkhai <ktkhai@parallels.com>2014-10-27 14:18:25 +0400
committerIngo Molnar <mingo@kernel.org>2014-10-28 10:45:59 +0100
commiteeb61e53ea19be0c4015b00b2e8b3b2185436f2b (patch)
tree87ed33506d580130ac59cc231a6e112c4042b96d /kernel
parentcac7f2429872d3733dc3f9915857b1691da2eb2f (diff)
downloadlinux-eeb61e53ea19be0c4015b00b2e8b3b2185436f2b.tar.bz2
sched: Fix race between task_group and sched_task_group
The race may happen when somebody is changing task_group of a forking task. Child's cgroup is the same as parent's after dup_task_struct() (there just memory copying). Also, cfs_rq and rt_rq are the same as parent's. But if parent changes its task_group before it's called cgroup_post_fork(), we do not reflect this situation on child. Child's cfs_rq and rt_rq remain the same, while child's task_group changes in cgroup_post_fork(). To fix this we introduce fork() method, which calls sched_move_task() directly. This function changes sched_task_group on appropriate (also its logic has no problem with freshly created tasks, so we shouldn't introduce something special; we are able just to use it). Possibly, this decides the Burke Libbey's problem: https://lkml.org/lkml/2014/10/24/456 Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1414405105.19914.169.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 44999505e1bf..dde8adb7d0c0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7833,6 +7833,11 @@ static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
sched_offline_group(tg);
}
+static void cpu_cgroup_fork(struct task_struct *task)
+{
+ sched_move_task(task);
+}
+
static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
@@ -8205,6 +8210,7 @@ struct cgroup_subsys cpu_cgrp_subsys = {
.css_free = cpu_cgroup_css_free,
.css_online = cpu_cgroup_css_online,
.css_offline = cpu_cgroup_css_offline,
+ .fork = cpu_cgroup_fork,
.can_attach = cpu_cgroup_can_attach,
.attach = cpu_cgroup_attach,
.exit = cpu_cgroup_exit,