Commit 1f7dd3e5a6e4 ("cgroup: fix handling of multi-destination migration
from subtree_control enabling") introduced the following compiler warning:
mm/memcontrol.c: In function ‘mem_cgroup_can_attach’:
mm/memcontrol.c:4790:9: warning: ‘memcg’ may be used uninitialized in this function [-Wmaybe-uninitialized]
mc.to = memcg;
^
Fix this by initializing 'memcg' to NULL and then verifying that it is set
to a value before dereferencing it.
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
This issue is present in v4.4-rc5 and later.
---
mm/memcontrol.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e234c21..69a28b3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4782,7 +4782,7 @@ static void mem_cgroup_clear_mc(void)
static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
- struct mem_cgroup *memcg;
+ struct mem_cgroup *memcg = NULL;
struct mem_cgroup *from;
struct task_struct *leader, *p;
struct mm_struct *mm;
@@ -4805,7 +4805,7 @@ static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
p = leader;
memcg = mem_cgroup_from_css(css);
}
- if (!p)
+ if (!p || !memcg)
return 0;
/*
--
2.6.3
--
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