From 895749455f6054e0c7b40a6ec449a3ab6db51bdd Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 16 Feb 2022 15:31:35 +1100 Subject: [PATCH] mm: simplify freeing of devmap managed pages Make put_devmap_managed_page return if it took charge of the page or not and remove the separate page_is_devmap_managed helper. Link: https://lkml.kernel.org/r/20220210072828.2930359-6-hch@lst.de Signed-off-by: Christoph Hellwig Reviewed-by: Logan Gunthorpe Reviewed-by: Jason Gunthorpe Reviewed-by: Chaitanya Kulkarni Reviewed-by: Dan Williams Tested-by: "Sierra Guiza, Alejandro (Alex)" Cc: Alex Deucher Cc: Alistair Popple Cc: Ben Skeggs Cc: Christian Knig Cc: Felix Kuehling Cc: Karol Herbst Cc: Lyude Paul Cc: Miaohe Lin Cc: Muchun Song Cc: "Pan, Xinhui" Cc: Ralph Campbell Signed-off-by: Andrew Morton Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/mm.h | 34 ++++++++++------------------------ mm/memremap.c | 20 +++++++++----------- mm/swap.c | 10 +--------- 3 files changed, 20 insertions(+), 44 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index a9d6473fc045..8a59f0456149 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1094,33 +1094,24 @@ static inline bool is_zone_movable_page(const struct page *page) #ifdef CONFIG_DEV_PAGEMAP_OPS DECLARE_STATIC_KEY_FALSE(devmap_managed_key); -static inline bool page_is_devmap_managed(struct page *page) +bool __put_devmap_managed_page(struct page *page); +static inline bool put_devmap_managed_page(struct page *page) { if (!static_branch_unlikely(&devmap_managed_key)) return false; if (!is_zone_device_page(page)) return false; - switch (page->pgmap->type) { - case MEMORY_DEVICE_PRIVATE: - case MEMORY_DEVICE_FS_DAX: - return true; - default: - break; - } - return false; + if (page->pgmap->type != MEMORY_DEVICE_PRIVATE && + page->pgmap->type != MEMORY_DEVICE_FS_DAX) + return false; + return __put_devmap_managed_page(page); } -void put_devmap_managed_page(struct page *page); - #else /* CONFIG_DEV_PAGEMAP_OPS */ -static inline bool page_is_devmap_managed(struct page *page) +static inline bool put_devmap_managed_page(struct page *page) { return false; } - -static inline void put_devmap_managed_page(struct page *page) -{ -} #endif /* CONFIG_DEV_PAGEMAP_OPS */ static inline bool is_device_private_page(const struct page *page) @@ -1220,16 +1211,11 @@ static inline void put_page(struct page *page) struct folio *folio = page_folio(page); /* - * For devmap managed pages we need to catch refcount transition from - * 2 to 1, when refcount reach one it means the page is free and we - * need to inform the device driver through callback. See - * include/linux/memremap.h and HMM for details. + * For some devmap managed pages we need to catch refcount transition + * from 2 to 1: */ - if (page_is_devmap_managed(&folio->page)) { - put_devmap_managed_page(&folio->page); + if (put_devmap_managed_page(&folio->page)) return; - } - folio_put(folio); } diff --git a/mm/memremap.c b/mm/memremap.c index 55d23e9f5c04..f41233a67edb 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -502,24 +502,22 @@ void free_devmap_managed_page(struct page *page) page->pgmap->ops->page_free(page); } -void put_devmap_managed_page(struct page *page) +bool __put_devmap_managed_page(struct page *page) { - int count; - - if (WARN_ON_ONCE(!page_is_devmap_managed(page))) - return; - - count = page_ref_dec_return(page); - /* * devmap page refcounts are 1-based, rather than 0-based: if * refcount is 1, then the page is free and the refcount is * stable because nobody holds a reference on the page. */ - if (count == 1) + switch (page_ref_dec_return(page)) { + case 1: free_devmap_managed_page(page); - else if (!count) + break; + case 0: __put_page(page); + break; + } + return true; } -EXPORT_SYMBOL(put_devmap_managed_page); +EXPORT_SYMBOL(__put_devmap_managed_page); #endif /* CONFIG_DEV_PAGEMAP_OPS */ diff --git a/mm/swap.c b/mm/swap.c index e499df864ef7..db8d0eea13d7 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -930,16 +930,8 @@ void release_pages(struct page **pages, int nr) unlock_page_lruvec_irqrestore(lruvec, flags); lruvec = NULL; } - /* - * ZONE_DEVICE pages that return 'false' from - * page_is_devmap_managed() do not require special - * processing, and instead, expect a call to - * put_page_testzero(). - */ - if (page_is_devmap_managed(page)) { - put_devmap_managed_page(page); + if (put_devmap_managed_page(page)) continue; - } if (put_page_testzero(page)) put_dev_pagemap(page->pgmap); continue; -- 2.11.0