From: John Hubbard <[email protected]> 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/[email protected] Proposed steps for fixing get_user_pages() + DMA problems. [3]https://lkml.kernel.org/r/[email protected] Bounce buffers (otherwise [2] is not really viable). [4] https://lkml.kernel.org/r/[email protected] Follow-up discussions. CC: Matthew Wilcox <[email protected]> CC: Michal Hocko <[email protected]> CC: Christopher Lameter <[email protected]> CC: Jason Gunthorpe <[email protected]> CC: Dan Williams <[email protected]> CC: Jan Kara <[email protected]> CC: Al Viro <[email protected]> CC: Jerome Glisse <[email protected]> CC: Christoph Hellwig <[email protected]> CC: Ralph Campbell <[email protected]> Signed-off-by: John Hubbard <[email protected]> --- 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
