Re: [PATCH 5/5] mm, slob: Trace allocation failures consistently

[JoonSoo Kim <js1304@gmail.com>]

2012/9/6 Ezequiel Garcia <elezegarcia@gmail.com>:
> This patch cleans how we trace kmalloc and kmem_cache_alloc.
> In particular, it fixes out-of-memory tracing: now every failed
> allocation will trace reporting non-zero requested bytes, zero obtained bytes.
>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: Christoph Lameter <cl@linux.com>
> Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
> ---
>  mm/slob.c |   30 ++++++++++++++++++------------
>  1 files changed, 18 insertions(+), 12 deletions(-)
>
> diff --git a/mm/slob.c b/mm/slob.c
> index 3f4dc9a..73f16ca 100644
> --- a/mm/slob.c
> +++ b/mm/slob.c
> @@ -428,6 +428,7 @@ static __always_inline void *
>  __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
>  {
>         int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
> +       size_t alloc_size = 0;
>         void *ret;
>
>         gfp &= gfp_allowed_mask;
> @@ -441,24 +442,25 @@ __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
>                 ret = slob_alloc(size + align, gfp, align, node);
>
>                 if (!ret)
> -                       return NULL;
> +                       goto trace_out;
>                 *(unsigned int *)ret = size;
>                 ret += align;
> -
> -               trace_kmalloc_node(caller, ret,
> -                                  size, size + align, gfp, node);
> +               alloc_size = size + align;
>         } else {
>                 unsigned int order = get_order(size);
>
>                 if (likely(order))
>                         gfp |= __GFP_COMP;
>                 ret = slob_new_pages(gfp, order, node);
> +               if (!ret)
> +                       goto trace_out;
>
> -               trace_kmalloc_node(caller, ret,
> -                                  size, PAGE_SIZE << order, gfp, node);
> +               alloc_size = PAGE_SIZE << order;
>         }
>
>         kmemleak_alloc(ret, size, 1, gfp);
> +trace_out:
> +       trace_kmalloc_node(caller, ret, size, alloc_size, gfp, node);
>         return ret;
>  }
>
> @@ -565,6 +567,7 @@ EXPORT_SYMBOL(kmem_cache_destroy);
>
>  void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
>  {
> +       size_t alloc_size = 0;
>         void *b;
>
>         flags &= gfp_allowed_mask;
> @@ -573,20 +576,23 @@ void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
>
>         if (c->size < PAGE_SIZE) {
>                 b = slob_alloc(c->size, flags, c->align, node);
> -               trace_kmem_cache_alloc_node(_RET_IP_, b, c->size,
> -                                           SLOB_UNITS(c->size) * SLOB_UNIT,
> -                                           flags, node);
> +               if (!b)
> +                       goto trace_out;
> +               alloc_size = SLOB_UNITS(c->size) * SLOB_UNIT;
>         } else {
>                 b = slob_new_pages(flags, get_order(c->size), node);
> -               trace_kmem_cache_alloc_node(_RET_IP_, b, c->size,
> -                                           PAGE_SIZE << get_order(c->size),
> -                                           flags, node);
> +               if (!b)
> +                       goto trace_out;
> +               alloc_size = PAGE_SIZE << get_order(c->size);
>         }
>
>         if (c->ctor)
>                 c->ctor(b);
>
>         kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags);
> +trace_out:
> +       trace_kmem_cache_alloc_node(_RET_IP_, b, c->size, alloc_size,
> +                                   flags, node);
>         return b;
>  }
>  EXPORT_SYMBOL(kmem_cache_alloc_node);
> --
> 1.7.8.6
>
> --
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If we don't enable tracing, "unused variable warning" may occurs.

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