ShiYong LI wrote:
Hi,
Compared to previous version, add alignment checking to make sure
memory space storing redzone2 and last user tags is 8 byte alignment.
From 949e8c29e8681a2359e23a8fbd8b9d4833f42344 Mon Sep 17 00:00:00 2001
From: Shiyong Li <shi-yong.li@xxxxxxxxxxxx>
Date: Mon, 12 Apr 2010 13:48:21 +0800
Subject: [PATCH] Fix missing of last user info while getting
DEBUG_SLAB config enabled.
Even with SLAB_RED_ZONE and SLAB_STORE_USER enabled, kernel would NOT
store redzone and last user data around allocated memory space if arch
cache line > sizeof(unsigned long long). As a result, last user information
is unexpectedly MISSED while dumping slab corruption log.
This fix makes sure that redzone and last user tags get stored unless
the required alignment breaks redzone's.
Signed-off-by: Shiyong Li <shi-yong.li@xxxxxxxxxxxx>
OK, I added this to linux-next for testing. Thanks!
---
mm/slab.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index a8a38ca..b97c57e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2267,8 +2267,8 @@ kmem_cache_create (const char *name, size_t
size, size_t align,
if (ralign < align) {
ralign = align;
}
- /* disable debug if necessary */
- if (ralign > __alignof__(unsigned long long))
+ /* disable debug if not aligning with REDZONE_ALIGN */
+ if (ralign & (__alignof__(unsigned long long) - 1))
flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
/*
* 4) Store it.
@@ -2289,8 +2289,8 @@ kmem_cache_create (const char *name, size_t
size, size_t align,
*/
if (flags & SLAB_RED_ZONE) {
/* add space for red zone words */
- cachep->obj_offset += sizeof(unsigned long long);
- size += 2 * sizeof(unsigned long long);
+ cachep->obj_offset += align;
+ size += align + sizeof(unsigned long long);
}
if (flags & SLAB_STORE_USER) {
/* user store requires one word storage behind the end of
--
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