Subject: + mm-slb-fix-misleading-comments.patch added to -mm tree
To: dave.hansen@xxxxxxxxxxxxxxx,cl@xxxxxxxxx,mpm@xxxxxxxxxxx,penberg@xxxxxxxxxx,rientjes@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 29 Jan 2014 11:25:46 -0800
The patch titled
Subject: mm: sl[uo]b: fix misleading comments
has been added to the -mm tree. Its filename is
mm-slb-fix-misleading-comments.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-slb-fix-misleading-comments.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-slb-fix-misleading-comments.patch
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From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Subject: mm: sl[uo]b: fix misleading comments
On x86, SLUB creates and handles <=8192-byte allocations internally. It
passes larger ones up to the allocator. Saying "up to order 2" is, at
best, ambiguous. Is that order-1? Or (order-2 bytes)? Make it more
clear.
SLOB commits a similar sin. It *handles* page-size requests, but the
comment says that it passes up "all page size and larger requests".
SLOB also swaps around the order of the very-similarly-named
KMALLOC_SHIFT_HIGH and KMALLOC_SHIFT_MAX #defines. Make it consistent
with the order of the other two allocators.
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/slab.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff -puN include/linux/slab.h~mm-slb-fix-misleading-comments include/linux/slab.h
--- a/include/linux/slab.h~mm-slb-fix-misleading-comments
+++ a/include/linux/slab.h
@@ -205,8 +205,8 @@ struct kmem_cache {
#ifdef CONFIG_SLUB
/*
- * SLUB allocates up to order 2 pages directly and otherwise
- * passes the request to the page allocator.
+ * SLUB directly allocates requests fitting in to an order-1 page
+ * (PAGE_SIZE*2). Larger requests are passed to the page allocator.
*/
#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
@@ -217,12 +217,12 @@ struct kmem_cache {
#ifdef CONFIG_SLOB
/*
- * SLOB passes all page size and larger requests to the page allocator.
+ * SLOB passes all requests larger than one page to the page allocator.
* No kmalloc array is necessary since objects of different sizes can
* be allocated from the same page.
*/
-#define KMALLOC_SHIFT_MAX 30
#define KMALLOC_SHIFT_HIGH PAGE_SHIFT
+#define KMALLOC_SHIFT_MAX 30
#ifndef KMALLOC_SHIFT_LOW
#define KMALLOC_SHIFT_LOW 3
#endif
_
Patches currently in -mm which might be from dave.hansen@xxxxxxxxxxxxxxx are
origin.patch
mm-slub-do-not-vm_bug_on_page-for-temporary-on-stack-pages.patch
mm-slubc-fix-page-_count-corruption-again.patch
mm-slb-fix-misleading-comments.patch
linux-next.patch
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