Re: [PATCH] mm-slab: allocate kmem_cache with __GFP_REPEAT

Pekka Enberg
2011-07-20T13:15:12Z

On Wed, 20 Jul 2011, Konstantin Khlebnikov wrote:
> Order of sizeof(struct kmem_cache) can be bigger than PAGE_ALLOC_COSTLY_ORDER,
> thus there is a good chance of unsuccessful allocation.
> With __GFP_REPEAT buddy-allocator will reclaim/compact memory more aggressively.
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
> ---
> mm/slab.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/slab.c b/mm/slab.c
> index d96e223..53bddc8 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -2304,7 +2304,7 @@ kmem_cache_create (const char *name, size_t size, size_t align,
> gfp = GFP_NOWAIT;
>
> /* Get cache's description obj. */
> - cachep = kmem_cache_zalloc(&cache_cache, gfp);
> + cachep = kmem_cache_zalloc(&cache_cache, gfp | __GFP_REPEAT);
> if (!cachep)
> goto oops;

The changelog isn't that convincing, really. This is kmem_cache_create()
so I'm surprised we'd ever get NULL here in practice. Does this fix some
problem you're seeing? If this is really an issue, I'd blame the page
allocator as GFP_KERNEL should just work.

Pekka