Re: [PATCH] mm/slab.c: check pointer slabp before using it in alloc_slabmgmt()

[Peter Hurley <peter@hurleysoftware.com>]

On 12/10/2013 10:35 AM, Christoph Lameter wrote:
> On Tue, 10 Dec 2013, Ethan Zhao wrote:
>
>>       No, stable 3.12.4 and 3.12.3 need this patch.  3.13RC doesn't
>> need it anymore.
>
> Hmmm.. Then this commit may have fixed it:

Cross-threaded from [Re: Slab BUG with DEBUG_* options ]

On 12/08/2013 10:00 AM, Meelis Roos wrote:
 > ldata alloc change + your second slab patch + slab debug: hang on boot
 > after
 > console [tty0] enabled, bootconsole disabled
 > (after that, I should see all the dmesg again on serial but I do not).

Meelis,

Please grab this patch below and see if it fixes your 'hang on boot'
with Christoph's other slab patch + slab debug.

Regards,
Peter Hurley

> commit 0172f779e4314639a8ed440082cfe9e3450954e8
> Author: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Date:   Wed Oct 30 19:04:00 2013 +0900
>
>      slab: fix to calm down kmemleak warning
>
>      After using struct page as slab management, we should not call
>      kmemleak_scan_area(), since struct page isn't the tracking object of
>      kmemleak. Without this patch and if CONFIG_DEBUG_KMEMLEAK is enabled,
>      so many kmemleak warnings are printed.
>
>      Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>      Signed-off-by: Pekka Enberg <penberg@iki.fi>
>
> diff --git a/mm/slab.c b/mm/slab.c
> index af2db76..a8a9349 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -2531,14 +2531,6 @@ static struct freelist *alloc_slabmgmt(struct
> kmem_cache *cachep,
>                  /* Slab management obj is off-slab. */
>                  freelist = kmem_cache_alloc_node(cachep->freelist_cache,
>                                                local_flags, nodeid);
> -               /*
> -                * If the first object in the slab is leaked (it's allocated
> -                * but no one has a reference to it), we want to make sure
> -                * kmemleak does not treat the ->s_mem pointer as a reference
> -                * to the object. Otherwise we will not report the leak.
> -                */
> -               kmemleak_scan_area(&page->lru, sizeof(struct list_head),
> -                                  local_flags);
>                  if (!freelist)
>                          return NULL;
>          } else {
>