Patch "slub: do not merge cache if slub_debug contains a never-merge flag" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    slub: do not merge cache if slub_debug contains a never-merge flag

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     slub-do-not-merge-cache-if-slub_debug-contains-a-never-merge-flag.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Oct 19 15:15:46 CEST 2017
From: Grygorii Maistrenko <grygoriimkd@gmail.com>
Date: Wed, 22 Feb 2017 15:40:59 -0800
Subject: slub: do not merge cache if slub_debug contains a never-merge flag

From: Grygorii Maistrenko <grygoriimkd@gmail.com>


[ Upstream commit c6e28895a4372992961888ffaadc9efc643b5bfe ]

In case CONFIG_SLUB_DEBUG_ON=n, find_mergeable() gets debug features from
commandline but never checks if there are features from the
SLAB_NEVER_MERGE set.

As a result selected by slub_debug caches are always mergeable if they
have been created without a custom constructor set or without one of the
SLAB_* debug features on.

This moves the SLAB_NEVER_MERGE check below the flags update from
commandline to make sure it won't merge the slab cache if one of the debug
features is on.

Link: http://lkml.kernel.org/r/20170101124451.GA4740@lp-laptop-d
Signed-off-by: Grygorii Maistrenko <grygoriimkd@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/slab_common.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -250,7 +250,7 @@ struct kmem_cache *find_mergeable(size_t
 {
 	struct kmem_cache *s;
 
-	if (slab_nomerge || (flags & SLAB_NEVER_MERGE))
+	if (slab_nomerge)
 		return NULL;
 
 	if (ctor)
@@ -261,6 +261,9 @@ struct kmem_cache *find_mergeable(size_t
 	size = ALIGN(size, align);
 	flags = kmem_cache_flags(size, flags, name, NULL);
 
+	if (flags & SLAB_NEVER_MERGE)
+		return NULL;
+
 	list_for_each_entry_reverse(s, &slab_caches, list) {
 		if (slab_unmergeable(s))
 			continue;


Patches currently in stable-queue which might be from grygoriimkd@gmail.com are

queue-4.4/slub-do-not-merge-cache-if-slub_debug-contains-a-never-merge-flag.patch