From: Christoph Lameter <cl@linux.com>
Date: Wed, 25 May 2011 14:47:43 +0000 (-0500)
Subject: slub: Fix double bit unlock in debug mode
X-Git-Tag: firefly_0821_release~7613^2~1294
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a71ae47a2cbfa542c69f695809124da4e4dd9e8f;p=firefly-linux-kernel-4.4.55.git

slub: Fix double bit unlock in debug mode

Commit 442b06bcea23 ("slub: Remove node check in slab_free") added a
call to deactivate_slab() in the debug case in __slab_alloc(), which
unlocks the current slab used for allocation.  Going to the label
'unlock_out' then does it again.

Also, in the debug case we do not need all the other processing that the
'unlock_out' path does.  We always fall back to the slow path in the
debug case.  So the tid update is useless.

Similarly, ALLOC_SLOWPATH would just be incremented for all allocations.
Also a pretty useless thing.

So simply restore irq flags and return the object.

Signed-off-by: Christoph Lameter <cl@linux.com>
Reported-and-bisected-by: James Morris <jmorris@namei.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Jens Axboe <jaxboe@fusionio.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/slub.c b/mm/slub.c
index 4ea7f1a22a94..4aad32d2e60d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1884,7 +1884,8 @@ debug:
 	deactivate_slab(s, c);
 	c->page = NULL;
 	c->node = NUMA_NO_NODE;
-	goto unlock_out;
+	local_irq_restore(flags);
+	return object;
 }
 
 /*