Hi Sidhartha,
On Fri, 6 Jan 2023 15:52:51 -0600 Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx> wrote:
> Add a folio equivalent for page_is_pfmemalloc. This removes two instances
> of page_is_pfmemalloc(folio_page(folio, 0)) so the folio can be used
> directly.
>
> Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Reviewed-by: SeongJae Park <sj@xxxxxxxxxx>
Thanks,
SJ
> ---
> include/linux/mm.h | 15 +++++++++++++++
> mm/slab.c | 2 +-
> mm/slub.c | 2 +-
> 3 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index c37f9330f14e..79d5a0cbf4c3 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1906,6 +1906,21 @@ static inline bool page_is_pfmemalloc(const struct page *page)
> return (uintptr_t)page->lru.next & BIT(1);
> }
>
> +/*
> + * Return true only if the folio has been allocated with
> + * ALLOC_NO_WATERMARKS and the low watermark was not
> + * met implying that the system is under some pressure.
> + */
> +static inline bool folio_is_pfmemalloc(const struct folio *folio)
> +{
> + /*
> + * lru.next has bit 1 set if the page is allocated from the
> + * pfmemalloc reserves. Callers may simply overwrite it if
> + * they do not need to preserve that information.
> + */
> + return (uintptr_t)folio->lru.next & BIT(1);
> +}
> +
> /*
> * Only to be called by the page allocator on a freshly allocated
> * page.
> diff --git a/mm/slab.c b/mm/slab.c
> index 7a269db050ee..01291ecbc0d8 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -1373,7 +1373,7 @@ static struct slab *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
> /* Make the flag visible before any changes to folio->mapping */
> smp_wmb();
> /* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
> - if (sk_memalloc_socks() && page_is_pfmemalloc(folio_page(folio, 0)))
> + if (sk_memalloc_socks() && folio_is_pfmemalloc(folio))
> slab_set_pfmemalloc(slab);
>
> return slab;
> diff --git a/mm/slub.c b/mm/slub.c
> index 13459c69095a..0cbe6eff23fa 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1859,7 +1859,7 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node,
> __folio_set_slab(folio);
> /* Make the flag visible before any changes to folio->mapping */
> smp_wmb();
> - if (page_is_pfmemalloc(folio_page(folio, 0)))
> + if (folio_is_pfmemalloc(folio))
> slab_set_pfmemalloc(slab);
>
> return slab;
> --
> 2.39.0
>
>
