| Date | Thu, 01 Jul 2010 10:43:57 -0700 | From | Greg KH <> | Subject | [147/200] cgroups: alloc_css_id() increments hierarchy depth |
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2.6.34-stable review patch. If anyone has any objections, please let me know.
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From: Greg Thelen <gthelen@google.com>
commit 94b3dd0f7bb393d93e84a173b1df9b8b64c83ac4 upstream.
Child groups should have a greater depth than their parents. Prior to this change, the parent would incorrectly report zero memory usage for child cgroups when use_hierarchy is enabled.
test script: mount -t cgroup none /cgroups -o memory cd /cgroups mkdir cg1
echo 1 > cg1/memory.use_hierarchy mkdir cg1/cg11
echo $$ > cg1/cg11/tasks dd if=/dev/zero of=/tmp/foo bs=1M count=1
echo echo CHILD grep cache cg1/cg11/memory.stat
echo echo PARENT grep cache cg1/memory.stat
echo $$ > tasks rmdir cg1/cg11 cg1 cd / umount /cgroups
Using fae9c79, a recent patch that changed alloc_css_id() depth computation, the parent incorrectly reports zero usage: root@ubuntu:~# ./test 1+0 records in 1+0 records out 1048576 bytes (1.0 MB) copied, 0.0151844 s, 69.1 MB/s
CHILD cache 1048576 total_cache 1048576
PARENT cache 0 total_cache 0
With this patch, the parent correctly includes child usage: root@ubuntu:~# ./test 1+0 records in 1+0 records out 1048576 bytes (1.0 MB) copied, 0.0136827 s, 76.6 MB/s
CHILD cache 1052672 total_cache 1052672
PARENT cache 0 total_cache 1052672
Signed-off-by: Greg Thelen <gthelen@google.com> Acked-by: Paul Menage <menage@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4599,7 +4599,7 @@ static int alloc_css_id(struct cgroup_su parent_css = parent->subsys[subsys_id]; child_css = child->subsys[subsys_id]; parent_id = parent_css->id; - depth = parent_id->depth; + depth = parent_id->depth + 1; child_id = get_new_cssid(ss, depth); if (IS_ERR(child_id))
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