On Fri, Sep 15, 2023 at 10:59:24AM +0000, Matteo Rizzo wrote:
> From: Jann Horn <jannh@xxxxxxxxxx>
>
> This is refactoring in preparation for SLAB_VIRTUAL. Extract this code
> to separate functions so that it's not duplicated in the code that
> allocates and frees page with SLAB_VIRTUAL enabled.
>
> Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
> Co-developed-by: Matteo Rizzo <matteorizzo@xxxxxxxxxx>
> Signed-off-by: Matteo Rizzo <matteorizzo@xxxxxxxxxx>
> ---
> mm/slub.c | 32 ++++++++++++++++++++++----------
> 1 file changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index ad33d9e1601d..9b87afade125 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1849,6 +1849,26 @@ static void *setup_object(struct kmem_cache *s, void *object)
> /*
> * Slab allocation and freeing
> */
> +
> +static void folio_set_slab(struct folio *folio, struct slab *slab)
> +{
> + __folio_set_slab(folio);
> + /* Make the flag visible before any changes to folio->mapping */
> + smp_wmb();
> +
> + if (folio_is_pfmemalloc(folio))
> + slab_set_pfmemalloc(slab);
> +}
> +
> +static void folio_clear_slab(struct folio *folio, struct slab *slab)
> +{
> + __slab_clear_pfmemalloc(slab);
> + folio->mapping = NULL;
> + /* Make the mapping reset visible before clearing the flag */
> + smp_wmb();
> + __folio_clear_slab(folio);
> +}
Perhaps these should be explicitly marked as inlines?
> +
> static inline struct slab *alloc_slab_page(gfp_t flags, int node,
> struct kmem_cache_order_objects oo)
> {
> @@ -1865,11 +1885,7 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node,
> return NULL;
>
> slab = folio_slab(folio);
> - __folio_set_slab(folio);
> - /* Make the flag visible before any changes to folio->mapping */
> - smp_wmb();
> - if (folio_is_pfmemalloc(folio))
> - slab_set_pfmemalloc(slab);
> + folio_set_slab(folio, slab);
>
> return slab;
> }
> @@ -2067,11 +2083,7 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab)
> int order = folio_order(folio);
> int pages = 1 << order;
>
> - __slab_clear_pfmemalloc(slab);
> - folio->mapping = NULL;
> - /* Make the mapping reset visible before clearing the flag */
> - smp_wmb();
> - __folio_clear_slab(folio);
> + folio_clear_slab(folio, slab);
> mm_account_reclaimed_pages(pages);
> unaccount_slab(slab, order, s);
> __free_pages(&folio->page, order);
> --
> 2.42.0.459.ge4e396fd5e-goog
Otherwise this is a straight function extraction.
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
--
Kees Cook
