linux-kernel - [PATCH] cgroup: alloc_css_id() increments hierarchy depth

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1275059781-9831-1-git-send-email-gthelen@google.com>
Date:	Fri, 28 May 2010 08:16:21 -0700
From:	Greg Thelen <gthelen@...gle.com>
To:	Paul Menage <menage@...gle.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Li Zefan <lizf@...fujitsu.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Ben Blum <bblum@...rew.cmu.edu>,
	containers@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, Greg Thelen <gthelen@...gle.com>
Subject: [PATCH] cgroup: alloc_css_id() increments hierarchy depth

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@...ntu:~# ./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@...ntu:~# ./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@...gle.com>
---
 kernel/cgroup.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 422cb19..3ac6f5b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4598,7 +4598,7 @@ static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
 	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))
-- 
1.7.0.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/