Re: [PATCH v3 2/6] mm/slab: Plumb kmem_buckets into __do_kmalloc_node()

Vlastimil Babka
2024-05-24T13:39:01Z

On 4/24/24 11:40 PM, Kees Cook wrote:
> To be able to choose which buckets to allocate from, make the buckets
> available to the lower level kmalloc interfaces by adding them as the
> first argument. Where the bucket is not available, pass NULL, which means
> "use the default system kmalloc bucket set" (the prior existing behavior),
> as implemented in kmalloc_slab().
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Roman Gushchin <roman.gushchin@linux.dev>
> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> Cc: linux-mm@kvack.org
> Cc: linux-hardening@vger.kernel.org
> ---
> include/linux/slab.h | 16 ++++++++--------
> lib/fortify_kunit.c | 2 +-
> mm/slab.h | 6 ++++--
> mm/slab_common.c | 4 ++--
> mm/slub.c | 14 +++++++-------
> mm/util.c | 2 +-
> 6 files changed, 23 insertions(+), 21 deletions(-)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index c8164d5db420..07373b680894 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -569,8 +569,8 @@ static __always_inline void kfree_bulk(size_t size, void **p)
> kmem_cache_free_bulk(NULL, size, p);
> }
>
> -void *__kmalloc_node_noprof(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment
> - __alloc_size(1);
> +void *__kmalloc_node_noprof(kmem_buckets *b, size_t size, gfp_t flags, int node)
> + __assume_kmalloc_alignment __alloc_size(2);
> #define __kmalloc_node(...) alloc_hooks(__kmalloc_node_noprof(__VA_ARGS__))
>
> void *kmem_cache_alloc_node_noprof(struct kmem_cache *s, gfp_t flags,
> @@ -679,7 +679,7 @@ static __always_inline __alloc_size(1) void *kmalloc_node_noprof(size_t size, gf
> kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
> flags, node, size);
> }
> - return __kmalloc_node_noprof(size, flags, node);
> + return __kmalloc_node_noprof(NULL, size, flags, node);

This is not ideal as now every kmalloc_node() callsite will now have to add
the NULL parameter even if this is not enabled. Could the new parameter be
only added depending on the respective config?

> }
> #define kmalloc_node(...) alloc_hooks(kmalloc_node_noprof(__VA_ARGS__))