]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commitdiff
slub: disable tracing and failslab for merged slabs
authorChristoph Lameter <cl@linux.com>
Thu, 9 Oct 2014 22:26:11 +0000 (15:26 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 10 Oct 2014 02:25:51 +0000 (22:25 -0400)
Tracing of mergeable slabs as well as uses of failslab are confusing since
the objects of multiple slab caches will be affected.  Moreover this
creates a situation where a mergeable slab will become unmergeable.

If tracing or failslab testing is desired then it may be best to switch
merging off for starters.

Signed-off-by: Christoph Lameter <cl@linux.com>
Tested-by: WANG Chao <chaowang@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/slub.c

index 3e8afcc07a760c552135cfb3c79ac924ee9e5494..fa86e58450935dc972a805ee932ed2dfc5e956db 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4604,6 +4604,14 @@ static ssize_t trace_show(struct kmem_cache *s, char *buf)
 static ssize_t trace_store(struct kmem_cache *s, const char *buf,
                                                        size_t length)
 {
+       /*
+        * Tracing a merged cache is going to give confusing results
+        * as well as cause other issues like converting a mergeable
+        * cache into an umergeable one.
+        */
+       if (s->refcount > 1)
+               return -EINVAL;
+
        s->flags &= ~SLAB_TRACE;
        if (buf[0] == '1') {
                s->flags &= ~__CMPXCHG_DOUBLE;
@@ -4721,6 +4729,9 @@ static ssize_t failslab_show(struct kmem_cache *s, char *buf)
 static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
                                                        size_t length)
 {
+       if (s->refcount > 1)
+               return -EINVAL;
+
        s->flags &= ~SLAB_FAILSLAB;
        if (buf[0] == '1')
                s->flags |= SLAB_FAILSLAB;