[merged] mm-slub-introduce-static-key-for-slub_debug.patch removed from -mm tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



The patch titled
     Subject: mm, slub: introduce static key for slub_debug()
has been removed from the -mm tree.  Its filename was
     mm-slub-introduce-static-key-for-slub_debug.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, slub: introduce static key for slub_debug()

One advantage of CONFIG_SLUB_DEBUG is that a generic distro kernel can be
built with the option enabled, but it's inactive until simply enabled on
boot, without rebuilding the kernel.  With a static key, we can further
eliminate the overhead of checking whether a cache has a particular debug
flag enabled if we know that there are no such caches (slub_debug was not
enabled during boot).  We use the same mechanism also for e.g. 
page_owner, debug_pagealloc or kmemcg functionality.

This patch introduces the static key and makes the general check for
per-cache debug flags kmem_cache_debug() use it.  This benefits several
call sites, including (slow path but still rather frequent) __slab_free().
The next patches will add more uses.

Link: http://lkml.kernel.org/r/20200610163135.17364-7-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/slub.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

--- a/mm/slub.c~mm-slub-introduce-static-key-for-slub_debug
+++ a/mm/slub.c
@@ -114,13 +114,21 @@
  * 			the fast path and disables lockless freelists.
  */
 
+#ifdef CONFIG_SLUB_DEBUG
+#ifdef CONFIG_SLUB_DEBUG_ON
+DEFINE_STATIC_KEY_TRUE(slub_debug_enabled);
+#else
+DEFINE_STATIC_KEY_FALSE(slub_debug_enabled);
+#endif
+#endif
+
 static inline int kmem_cache_debug(struct kmem_cache *s)
 {
 #ifdef CONFIG_SLUB_DEBUG
-	return unlikely(s->flags & SLAB_DEBUG_FLAGS);
-#else
-	return 0;
+	if (static_branch_unlikely(&slub_debug_enabled))
+		return s->flags & SLAB_DEBUG_FLAGS;
 #endif
+	return 0;
 }
 
 void *fixup_red_left(struct kmem_cache *s, void *p)
@@ -1389,6 +1397,8 @@ static int __init setup_slub_debug(char
 		slub_debug_string = saved_str;
 	}
 out:
+	if (slub_debug != 0 || slub_debug_string)
+		static_branch_enable(&slub_debug_enabled);
 	if ((static_branch_unlikely(&init_on_alloc) ||
 	     static_branch_unlikely(&init_on_free)) &&
 	    (slub_debug & SLAB_POISON))
_

Patches currently in -mm which might be from vbabka@xxxxxxx are





[Index of Archives]     [Kernel Archive]     [IETF Annouce]     [DCCP]     [Netdev]     [Networking]     [Security]     [Bugtraq]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux SCSI]

  Powered by Linux