On Wed, Apr 29, 2020 at 6:37 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
>
> This new function allows page cache pages to be allocated that are
> larger than an order-0 page.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
> include/linux/pagemap.h | 24 +++++++++++++++++++++---
> mm/filemap.c | 12 ++++++++----
> 2 files changed, 29 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 55199cb5bd66..1169e2428dd7 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -205,15 +205,33 @@ static inline int page_cache_add_speculative(struct page *page, int count)
> return __page_cache_add_speculative(page, count);
> }
>
> +static inline gfp_t thp_gfpmask(gfp_t gfp)
> +{
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> + /* We'd rather allocate smaller pages than stall a page fault */
> + gfp |= GFP_TRANSHUGE_LIGHT;
This looks not correct. GFP_TRANSHUGE_LIGHT may set GFP_FS, but some
filesystem may expect GFP_NOFS, i.e. in readahead path.
> + gfp &= ~__GFP_DIRECT_RECLAIM;
> +#endif
> + return gfp;
> +}
> +
> #ifdef CONFIG_NUMA
> -extern struct page *__page_cache_alloc(gfp_t gfp);
> +extern struct page *__page_cache_alloc_order(gfp_t gfp, unsigned int order);
> #else
> -static inline struct page *__page_cache_alloc(gfp_t gfp)
> +static inline
> +struct page *__page_cache_alloc_order(gfp_t gfp, unsigned int order)
> {
> - return alloc_pages(gfp, 0);
> + if (order == 0)
> + return alloc_pages(gfp, 0);
> + return prep_transhuge_page(alloc_pages(thp_gfpmask(gfp), order));
> }
> #endif
>
> +static inline struct page *__page_cache_alloc(gfp_t gfp)
> +{
> + return __page_cache_alloc_order(gfp, 0);
> +}
> +
> static inline struct page *page_cache_alloc(struct address_space *x)
> {
> return __page_cache_alloc(mapping_gfp_mask(x));
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 23a051a7ef0f..9abba062973a 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -941,24 +941,28 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
> EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
>
> #ifdef CONFIG_NUMA
> -struct page *__page_cache_alloc(gfp_t gfp)
> +struct page *__page_cache_alloc_order(gfp_t gfp, unsigned int order)
> {
> int n;
> struct page *page;
>
> + if (order > 0)
> + gfp = thp_gfpmask(gfp);
> +
> if (cpuset_do_page_mem_spread()) {
> unsigned int cpuset_mems_cookie;
> do {
> cpuset_mems_cookie = read_mems_allowed_begin();
> n = cpuset_mem_spread_node();
> - page = __alloc_pages_node(n, gfp, 0);
> + page = __alloc_pages_node(n, gfp, order);
> + prep_transhuge_page(page);
> } while (!page && read_mems_allowed_retry(cpuset_mems_cookie));
>
> return page;
> }
> - return alloc_pages(gfp, 0);
> + return prep_transhuge_page(alloc_pages(gfp, order));
> }
> -EXPORT_SYMBOL(__page_cache_alloc);
> +EXPORT_SYMBOL(__page_cache_alloc_order);
> #endif
>
> /*
> --
> 2.26.2
>
>
