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SubjectRe: [PROBLEM] 2.6.22-rc2 panics on x86-64 with slub
On Mon, 21 May 2007, Christoph Lameter wrote:
> On Mon, 21 May 2007, Hugh Dickins wrote:
>
> > Yes, sounded the same to me too: I couldn't reproduce it or see anything
> > wrong in the code back then. But Srihari's info about CONFIG_DEBUG_SLUB
> > off has helped a lot: I was then able to reproduce it on my x86_64, and
> > after a lot of staring at the code, the problem became obvious...
>
> Right. The #ifdef CONFIG_SLUB_DEBUG is at the wrong location. The best fix
> is to moving the #ifdef otherwise the size is still wrong for the
> ctor case.

? My patch did handle the ctor case.

>
> SLUB Debug: Fix object size calculation
>
> The object size calculation is wrong if !CONFIG_SLUB_DEBUG because
> the #ifdef CONFIG_SLUB_DEBUG is now switching off the size adjustments
> for DESTROY_BY_RCU and ctor.
>
> Signed-off-by: Christoph Lameter <clameter@sgi.com>

Yes, I think that should do it too. The reason behind my repeating
the block was to handle the case where SLAB_POISON is passed to
kmem_cache_create, but CONFIG_SLUB_DEBUG is off. But apparently
that case would hit the BUG_ON(flags & ~CREATE_MASK), therefore
your patch is simpler and better. Quite a maze.

Hugh

>
> ---
> mm/slub.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Index: slub/mm/slub.c
> ===================================================================
> --- slub.orig/mm/slub.c 2007-05-21 11:21:36.000000000 -0700
> +++ slub/mm/slub.c 2007-05-21 11:21:49.000000000 -0700
> @@ -1943,7 +1943,6 @@ static int calculate_sizes(struct kmem_c
> */
> s->inuse = size;
>
> -#ifdef CONFIG_SLUB_DEBUG
> if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
> s->ctor)) {
> /*
> @@ -1958,6 +1957,7 @@ static int calculate_sizes(struct kmem_c
> size += sizeof(void *);
> }
>
> +#ifdef CONFIG_SLUB_DEBUG
> if (flags & SLAB_STORE_USER)
> /*
> * Need to store information about allocs and frees after
-
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