From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: john.hubbard@gmail.com To: Matthew Wilcox , Michal Hocko , Christopher Lameter , Jason Gunthorpe , Dan Williams , Jan Kara Cc: linux-mm@kvack.org, LKML , linux-rdma , linux-fsdevel@vger.kernel.org, John Hubbard , Al Viro , Jerome Glisse , Christoph Hellwig , Ralph Campbell Subject: [PATCH v3 2/3] mm: introduce put_user_page*(), placeholder versions Date: Fri, 5 Oct 2018 19:49:48 -0700 Message-Id: <20181006024949.20691-3-jhubbard@nvidia.com> In-Reply-To: <20181006024949.20691-1-jhubbard@nvidia.com> References: <20181006024949.20691-1-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: From: John Hubbard Introduces put_user_page(), which simply calls put_page(). This provides a way to update all get_user_pages*() callers, so that they call put_user_page(), instead of put_page(). Also introduces put_user_pages(), and a few dirty/locked variations, as a replacement for release_pages(), and also as a replacement for open-coded loops that release multiple pages. These may be used for subsequent performance improvements, via batching of pages to be released. This prepares for eventually fixing the problem described in [1], and is following a plan listed in [2], [3], [4]. [1] https://lwn.net/Articles/753027/ : "The Trouble with get_user_pages()" [2] https://lkml.kernel.org/r/20180709080554.21931-1-jhubbard@nvidia.com Proposed steps for fixing get_user_pages() + DMA problems. [3]https://lkml.kernel.org/r/20180710082100.mkdwngdv5kkrcz6n@quack2.suse.cz Bounce buffers (otherwise [2] is not really viable). [4] https://lkml.kernel.org/r/20181003162115.GG24030@quack2.suse.cz Follow-up discussions. CC: Matthew Wilcox CC: Michal Hocko CC: Christopher Lameter CC: Jason Gunthorpe CC: Dan Williams CC: Jan Kara CC: Al Viro CC: Jerome Glisse CC: Christoph Hellwig CC: Ralph Campbell Signed-off-by: John Hubbard --- include/linux/mm.h | 48 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 46 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 0416a7204be3..305b206e6851 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -137,6 +137,8 @@ extern int overcommit_ratio_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *); extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *); +int set_page_dirty(struct page *page); +int set_page_dirty_lock(struct page *page); #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n)) @@ -943,6 +945,50 @@ static inline void put_page(struct page *page) __put_page(page); } +/* Pages that were pinned via get_user_pages*() should be released via + * either put_user_page(), or one of the put_user_pages*() routines + * below. + */ +static inline void put_user_page(struct page *page) +{ + put_page(page); +} + +static inline void put_user_pages_dirty(struct page **pages, + unsigned long npages) +{ + unsigned long index; + + for (index = 0; index < npages; index++) { + if (!PageDirty(pages[index])) + set_page_dirty(pages[index]); + + put_user_page(pages[index]); + } +} + +static inline void put_user_pages_dirty_lock(struct page **pages, + unsigned long npages) +{ + unsigned long index; + + for (index = 0; index < npages; index++) { + if (!PageDirty(pages[index])) + set_page_dirty_lock(pages[index]); + + put_user_page(pages[index]); + } +} + +static inline void put_user_pages(struct page **pages, + unsigned long npages) +{ + unsigned long index; + + for (index = 0; index < npages; index++) + put_user_page(pages[index]); +} + #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define SECTION_IN_PAGE_FLAGS #endif @@ -1534,8 +1580,6 @@ int redirty_page_for_writepage(struct writeback_control *wbc, void account_page_dirtied(struct page *page, struct address_space *mapping); void account_page_cleaned(struct page *page, struct address_space *mapping, struct bdi_writeback *wb); -int set_page_dirty(struct page *page); -int set_page_dirty_lock(struct page *page); void __cancel_dirty_page(struct page *page); static inline void cancel_dirty_page(struct page *page) { -- 2.19.0