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authorDave Jones <davej@redhat.com>2014-01-29 14:05:48 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-29 16:22:40 -0800
commitba3253c78d7443d2c80c544b1e7aec9f39938395 (patch)
tree450625e2e787ca1f9da46d97cec3967678a6a7e4 /mm
parent49382d93852f1ba4a4fbbce20d094f600cc8aff8 (diff)
downloadlinux-ba3253c78d7443d2c80c544b1e7aec9f39938395.tar.gz
slab: fix wrong retval on kmem_cache_create_memcg error path
On kmem_cache_create_memcg() error path we set 'err', but leave 's' (the new cache ptr) undefined. The latter can be NULL if we could not allocate the cache, or pointing to a freed area if we failed somewhere later while trying to initialize it. Initially we checked 'err' immediately before exiting the function and returned NULL if it was set ignoring the value of 's': out_unlock: ... if (err) { /* report error */ return NULL; } return s; Recently this check was, in fact, broken by commit f717eb3abb5e ("slab: do not panic if we fail to create memcg cache"), which turned it to: out_unlock: ... if (err && !memcg) { /* report error */ return NULL; } return s; As a result, if we are failing creating a cache for a memcg, we will skip the check and return 's' that can contain crap. Obviously, commit f717eb3abb5e intended not to return crap on error allocating a cache for a memcg, but only to remove the error reporting in this case, so the check should look like this: out_unlock: ... if (err) { if (!memcg) return NULL; /* report error */ return NULL; } return s; [rientjes@google.com: despaghettification] [vdavydov@parallels.com: patch monkeying] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Dave Jones <davej@redhat.com> Reported-by: Dave Jones <davej@redhat.com> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/slab_common.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 8e40321da09..1ec3c619ba0 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -233,14 +233,17 @@ out_unlock:
mutex_unlock(&slab_mutex);
put_online_cpus();
- /*
- * There is no point in flooding logs with warnings or especially
- * crashing the system if we fail to create a cache for a memcg. In
- * this case we will be accounting the memcg allocation to the root
- * cgroup until we succeed to create its own cache, but it isn't that
- * critical.
- */
- if (err && !memcg) {
+ if (err) {
+ /*
+ * There is no point in flooding logs with warnings or
+ * especially crashing the system if we fail to create a cache
+ * for a memcg. In this case we will be accounting the memcg
+ * allocation to the root cgroup until we succeed to create its
+ * own cache, but it isn't that critical.
+ */
+ if (!memcg)
+ return NULL;
+
if (flags & SLAB_PANIC)
panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
name, err);