Re: [PATCH] mm, slub: do not add duplicate sysfs

From: Christoph Lameter
Date: Wed Aug 27 2014 - 11:32:25 EST

Maybe something like this may be a proper fix:

Subject: slub: Disable tracing of mergeable slabs

Tracing of mergeable slabs is confusing since the objects
of multiple slab caches will be traced. Moreover this creates
a situation where a mergeable slab will become unmergeable.

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

Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>

Index: linux/mm/slub.c
--- linux.orig/mm/slub.c 2014-08-08 11:52:30.039681592 -0500
+++ linux/mm/slub.c 2014-08-27 10:30:16.508108726 -0500
@@ -4604,6 +4604,14 @@ static ssize_t trace_show(struct kmem_ca
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;
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