From: John Hubbard jhubbard@nvidia.com
Provide more capable variation of put_user_pages_dirty_lock(), and delete put_user_pages_dirty(). This is based on the following:
1. Lots of call sites become simpler if a bool is passed into put_user_page*(), instead of making the call site choose which put_user_page*() variant to call.
2. Christoph Hellwig's observation that set_page_dirty_lock() is usually correct, and set_page_dirty() is usually a bug, or at least questionable, within a put_user_page*() calling chain.
This leads to the following API choices:
* put_user_pages_dirty_lock(page, npages, make_dirty)
* There is no put_user_pages_dirty(). You have to hand code that, in the rare case that it's required.
Cc: Matthew Wilcox willy@infradead.org Cc: Jan Kara jack@suse.cz Cc: Christoph Hellwig hch@lst.de Cc: Ira Weiny ira.weiny@intel.com Cc: Jason Gunthorpe jgg@ziepe.ca Signed-off-by: John Hubbard jhubbard@nvidia.com --- drivers/infiniband/core/umem.c | 5 +- drivers/infiniband/hw/hfi1/user_pages.c | 5 +- drivers/infiniband/hw/qib/qib_user_pages.c | 5 +- drivers/infiniband/hw/usnic/usnic_uiom.c | 5 +- drivers/infiniband/sw/siw/siw_mem.c | 10 +- include/linux/mm.h | 5 +- mm/gup.c | 115 +++++++++------------ 7 files changed, 58 insertions(+), 92 deletions(-)
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index 08da840ed7ee..965cf9dea71a 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -54,10 +54,7 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) { page = sg_page_iter_page(&sg_iter); - if (umem->writable && dirty) - put_user_pages_dirty_lock(&page, 1); - else - put_user_page(page); + put_user_pages_dirty_lock(&page, 1, umem->writable && dirty); }
sg_free_table(&umem->sg_head); diff --git a/drivers/infiniband/hw/hfi1/user_pages.c b/drivers/infiniband/hw/hfi1/user_pages.c index b89a9b9aef7a..469acb961fbd 100644 --- a/drivers/infiniband/hw/hfi1/user_pages.c +++ b/drivers/infiniband/hw/hfi1/user_pages.c @@ -118,10 +118,7 @@ int hfi1_acquire_user_pages(struct mm_struct *mm, unsigned long vaddr, size_t np void hfi1_release_user_pages(struct mm_struct *mm, struct page **p, size_t npages, bool dirty) { - if (dirty) - put_user_pages_dirty_lock(p, npages); - else - put_user_pages(p, npages); + put_user_pages_dirty_lock(p, npages, dirty);
if (mm) { /* during close after signal, mm can be NULL */ atomic64_sub(npages, &mm->pinned_vm); diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c index bfbfbb7e0ff4..6bf764e41891 100644 --- a/drivers/infiniband/hw/qib/qib_user_pages.c +++ b/drivers/infiniband/hw/qib/qib_user_pages.c @@ -40,10 +40,7 @@ static void __qib_release_user_pages(struct page **p, size_t num_pages, int dirty) { - if (dirty) - put_user_pages_dirty_lock(p, num_pages); - else - put_user_pages(p, num_pages); + put_user_pages_dirty_lock(p, num_pages, dirty); }
/** diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c index 0b0237d41613..62e6ffa9ad78 100644 --- a/drivers/infiniband/hw/usnic/usnic_uiom.c +++ b/drivers/infiniband/hw/usnic/usnic_uiom.c @@ -75,10 +75,7 @@ static void usnic_uiom_put_pages(struct list_head *chunk_list, int dirty) for_each_sg(chunk->page_list, sg, chunk->nents, i) { page = sg_page(sg); pa = sg_phys(sg); - if (dirty) - put_user_pages_dirty_lock(&page, 1); - else - put_user_page(page); + put_user_pages_dirty_lock(&page, 1, dirty); usnic_dbg("pa: %pa\n", &pa); } kfree(chunk); diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c index 67171c82b0c4..ab83a9cec562 100644 --- a/drivers/infiniband/sw/siw/siw_mem.c +++ b/drivers/infiniband/sw/siw/siw_mem.c @@ -63,15 +63,7 @@ struct siw_mem *siw_mem_id2obj(struct siw_device *sdev, int stag_index) static void siw_free_plist(struct siw_page_chunk *chunk, int num_pages, bool dirty) { - struct page **p = chunk->plist; - - while (num_pages--) { - if (!PageDirty(*p) && dirty) - put_user_pages_dirty_lock(p, 1); - else - put_user_page(*p); - p++; - } + put_user_pages_dirty_lock(chunk->plist, num_pages, dirty); }
void siw_umem_release(struct siw_umem *umem, bool dirty) diff --git a/include/linux/mm.h b/include/linux/mm.h index 0334ca97c584..9759b6a24420 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1057,8 +1057,9 @@ static inline void put_user_page(struct page *page) put_page(page); }
-void put_user_pages_dirty(struct page **pages, unsigned long npages); -void put_user_pages_dirty_lock(struct page **pages, unsigned long npages); +void put_user_pages_dirty_lock(struct page **pages, unsigned long npages, + bool make_dirty); + void put_user_pages(struct page **pages, unsigned long npages);
#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) diff --git a/mm/gup.c b/mm/gup.c index 98f13ab37bac..7fefd7ab02c4 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -29,85 +29,70 @@ struct follow_page_context { unsigned int page_mask; };
-typedef int (*set_dirty_func_t)(struct page *page); - -static void __put_user_pages_dirty(struct page **pages, - unsigned long npages, - set_dirty_func_t sdf) -{ - unsigned long index; - - for (index = 0; index < npages; index++) { - struct page *page = compound_head(pages[index]); - - /* - * Checking PageDirty at this point may race with - * clear_page_dirty_for_io(), but that's OK. Two key cases: - * - * 1) This code sees the page as already dirty, so it skips - * the call to sdf(). That could happen because - * clear_page_dirty_for_io() called page_mkclean(), - * followed by set_page_dirty(). However, now the page is - * going to get written back, which meets the original - * intention of setting it dirty, so all is well: - * clear_page_dirty_for_io() goes on to call - * TestClearPageDirty(), and write the page back. - * - * 2) This code sees the page as clean, so it calls sdf(). - * The page stays dirty, despite being written back, so it - * gets written back again in the next writeback cycle. - * This is harmless. - */ - if (!PageDirty(page)) - sdf(page); - - put_user_page(page); - } -} - /** - * put_user_pages_dirty() - release and dirty an array of gup-pinned pages - * @pages: array of pages to be marked dirty and released. + * put_user_pages_dirty_lock() - release and optionally dirty gup-pinned pages + * @pages: array of pages to be maybe marked dirty, and definitely released. * @npages: number of pages in the @pages array. + * @make_dirty: whether to mark the pages dirty * * "gup-pinned page" refers to a page that has had one of the get_user_pages() * variants called on that page. * * For each page in the @pages array, make that page (or its head page, if a - * compound page) dirty, if it was previously listed as clean. Then, release - * the page using put_user_page(). + * compound page) dirty, if @make_dirty is true, and if the page was previously + * listed as clean. In any case, releases all pages using put_user_page(), + * possibly via put_user_pages(), for the non-dirty case. * * Please see the put_user_page() documentation for details. * - * set_page_dirty(), which does not lock the page, is used here. - * Therefore, it is the caller's responsibility to ensure that this is - * safe. If not, then put_user_pages_dirty_lock() should be called instead. + * set_page_dirty_lock() is used internally. If instead, set_page_dirty() is + * required, then the caller should a) verify that this is really correct, + * because _lock() is usually required, and b) hand code it: + * set_page_dirty_lock(), put_user_page(). * */ -void put_user_pages_dirty(struct page **pages, unsigned long npages) +void put_user_pages_dirty_lock(struct page **pages, unsigned long npages, + bool make_dirty) { - __put_user_pages_dirty(pages, npages, set_page_dirty); -} -EXPORT_SYMBOL(put_user_pages_dirty); + unsigned long index;
-/** - * put_user_pages_dirty_lock() - release and dirty an array of gup-pinned pages - * @pages: array of pages to be marked dirty and released. - * @npages: number of pages in the @pages array. - * - * For each page in the @pages array, make that page (or its head page, if a - * compound page) dirty, if it was previously listed as clean. Then, release - * the page using put_user_page(). - * - * Please see the put_user_page() documentation for details. - * - * This is just like put_user_pages_dirty(), except that it invokes - * set_page_dirty_lock(), instead of set_page_dirty(). - * - */ -void put_user_pages_dirty_lock(struct page **pages, unsigned long npages) -{ - __put_user_pages_dirty(pages, npages, set_page_dirty_lock); + /* + * TODO: this can be optimized for huge pages: if a series of pages is + * physically contiguous and part of the same compound page, then a + * single operation to the head page should suffice. + */ + + if (!make_dirty) { + put_user_pages(pages, npages); + return; + } + + for (index = 0; index < npages; index++) { + struct page *page = compound_head(pages[index]); + /* + * Checking PageDirty at this point may race with + * clear_page_dirty_for_io(), but that's OK. Two key + * cases: + * + * 1) This code sees the page as already dirty, so it + * skips the call to set_page_dirty(). That could happen + * because clear_page_dirty_for_io() called + * page_mkclean(), followed by set_page_dirty(). + * However, now the page is going to get written back, + * which meets the original intention of setting it + * dirty, so all is well: clear_page_dirty_for_io() goes + * on to call TestClearPageDirty(), and write the page + * back. + * + * 2) This code sees the page as clean, so it calls + * set_page_dirty(). The page stays dirty, despite being + * written back, so it gets written back again in the + * next writeback cycle. This is harmless. + */ + if (!PageDirty(page)) + set_page_dirty_lock(page); + put_user_page(page); + } } EXPORT_SYMBOL(put_user_pages_dirty_lock);