linux-kernel - [patch 2/3] mm: memcontrol: pull the NULL check from __mem_cgroup_same_or

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

Message-Id: <1414158589-26094-2-git-send-email-hannes@cmpxchg.org>
Date:	Fri, 24 Oct 2014 09:49:48 -0400
From:	Johannes Weiner <hannes@...xchg.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Michal Hocko <mhocko@...e.cz>,
	Vladimir Davydov <vdavydov@...allels.com>, linux-mm@...ck.org,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [patch 2/3] mm: memcontrol: pull the NULL check from __mem_cgroup_same_or_subtree()

The NULL in mm_match_cgroup() comes from a possibly exiting mm->owner.
It makes a lot more sense to check where it's looked up, rather than
check for it in __mem_cgroup_same_or_subtree() where it's unexpected.

No other callsite passes NULL to __mem_cgroup_same_or_subtree().

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
 include/linux/memcontrol.h | 5 +++--
 mm/memcontrol.c            | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index ea007615e8f9..e32ab948f589 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -83,11 +83,12 @@ static inline
 bool mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *memcg)
 {
 	struct mem_cgroup *task_memcg;
-	bool match;
+	bool match = false;
 
 	rcu_read_lock();
 	task_memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
-	match = __mem_cgroup_same_or_subtree(memcg, task_memcg);
+	if (task_memcg)
+		match = __mem_cgroup_same_or_subtree(memcg, task_memcg);
 	rcu_read_unlock();
 	return match;
 }
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bdf8520979cf..15b1c5110a8f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1316,7 +1316,7 @@ bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
 {
 	if (root_memcg == memcg)
 		return true;
-	if (!root_memcg->use_hierarchy || !memcg)
+	if (!root_memcg->use_hierarchy)
 		return false;
 	return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup);
 }
-- 
2.1.2

--
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/