[PATCH - V2] Fix missing of last user while dumping slab corruption log
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From: ShiYong LI on 12 Apr 2010 02:00 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(a)motorola.com> 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(a)motorola.com> --- 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 -- 1.6.0.4 -- Thanks & Best Regards Shiyong -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |