On Mon, Aug 29, 2022 at 03:56:15PM +0800, Feng Tang wrote:
> kmalloc's API family is critical for mm, with one nature that it will
> round up the request size to a fixed one (mostly power of 2). Say
> when user requests memory for '2^n + 1' bytes, actually 2^(n+1) bytes
> could be allocated, so in worst case, there is around 50% memory
> space waste.
>
[...]
> static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
> - unsigned long addr, struct kmem_cache_cpu *c)
> + unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size)
> {
> void *freelist;
> struct slab *slab;
> @@ -3115,6 +3158,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
>
> if (s->flags & SLAB_STORE_USER)
> set_track(s, freelist, TRACK_ALLOC, addr);
> + set_orig_size(s, freelist, orig_size);
>
> return freelist;
> }
> @@ -3140,6 +3184,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
> */
> if (s->flags & SLAB_STORE_USER)
> set_track(s, freelist, TRACK_ALLOC, addr);
> + set_orig_size(s, freelist, orig_size);
> +
> return freelist;
> }
Maybe we can move set_track() and set_orig_size() to after slab_post_alloc_hook().
something like alloc/free hooks for debugging caches? (and drop orig_size parameter.)
Thanks!
>
> @@ -3182,7 +3228,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
> * pointer.
> */
> static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
> - unsigned long addr, struct kmem_cache_cpu *c)
> + unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size)
> {
> void *p;
--
Thanks,
Hyeonggon
