From: John Hubbard <jhubb...@nvidia.com> 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-jhubb...@nvidia.com Proposed steps for fixing get_user_pages() + DMA problems. [3]https://lkml.kernel.org/r/20180710082100.mkdwngdv5kkrc...@quack2.suse.cz Bounce buffers (otherwise [2] is not really viable). [4] https://lkml.kernel.org/r/20181003162115.gg24...@quack2.suse.cz Follow-up discussions. CC: Matthew Wilcox <wi...@infradead.org> CC: Michal Hocko <mho...@kernel.org> CC: Christopher Lameter <c...@linux.com> CC: Jason Gunthorpe <j...@ziepe.ca> CC: Dan Williams <dan.j.willi...@intel.com> CC: Jan Kara <j...@suse.cz> CC: Al Viro <v...@zeniv.linux.org.uk> CC: Jerome Glisse <jgli...@redhat.com> CC: Christoph Hellwig <h...@infradead.org> CC: Ralph Campbell <rcampb...@nvidia.com> Reviewed-by: Jan Kara <j...@suse.cz> Signed-off-by: John Hubbard <jhubb...@nvidia.com> --- include/linux/mm.h | 49 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 47 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 0416a7204be3..0490f4a71b9c 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 +945,51 @@ 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 +1581,6 @@ 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
