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author | 2021-12-27 18:40:41 -0500 | |
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committer | 2022-03-21 12:56:35 -0400 | |
commit | 0b90ddae13441c43a30d2e2689b8193a81891c92 (patch) | |
tree | eecaae0094d56efc990cfa710fafe3b77d687478 /include/linux/mm.h | |
parent | mm: Add folio_pincount_ptr() (diff) | |
download | linux-0b90ddae13441c43a30d2e2689b8193a81891c92.tar.gz linux-0b90ddae13441c43a30d2e2689b8193a81891c92.tar.bz2 linux-0b90ddae13441c43a30d2e2689b8193a81891c92.zip |
mm: Turn page_maybe_dma_pinned() into folio_maybe_dma_pinned()
Replace three calls to compound_head() with one. This removes the last
user of compound_pincount(), so remove that helper too.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Diffstat (limited to 'include/linux/mm.h')
-rw-r--r-- | include/linux/mm.h | 129 |
1 files changed, 63 insertions, 66 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index c45739dfdd04..35e453ac5c0f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -892,13 +892,6 @@ static inline int head_compound_pincount(struct page *head) return atomic_read(compound_pincount_ptr(head)); } -static inline int compound_pincount(struct page *page) -{ - VM_BUG_ON_PAGE(!PageCompound(page), page); - page = compound_head(page); - return head_compound_pincount(page); -} - static inline void set_compound_order(struct page *page, unsigned int order) { page[1].compound_order = order; @@ -1236,70 +1229,11 @@ void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages, bool make_dirty); void unpin_user_pages(struct page **pages, unsigned long npages); -/** - * page_maybe_dma_pinned - Report if a page is pinned for DMA. - * @page: The page. - * - * This function checks if a page has been pinned via a call to - * a function in the pin_user_pages() family. - * - * For non-huge pages, the return value is partially fuzzy: false is not fuzzy, - * because it means "definitely not pinned for DMA", but true means "probably - * pinned for DMA, but possibly a false positive due to having at least - * GUP_PIN_COUNTING_BIAS worth of normal page references". - * - * False positives are OK, because: a) it's unlikely for a page to get that many - * refcounts, and b) all the callers of this routine are expected to be able to - * deal gracefully with a false positive. - * - * For huge pages, the result will be exactly correct. That's because we have - * more tracking data available: the 3rd struct page in the compound page is - * used to track the pincount (instead using of the GUP_PIN_COUNTING_BIAS - * scheme). - * - * For more information, please see Documentation/core-api/pin_user_pages.rst. - * - * Return: True, if it is likely that the page has been "dma-pinned". - * False, if the page is definitely not dma-pinned. - */ -static inline bool page_maybe_dma_pinned(struct page *page) -{ - if (PageCompound(page)) - return compound_pincount(page) > 0; - - /* - * page_ref_count() is signed. If that refcount overflows, then - * page_ref_count() returns a negative value, and callers will avoid - * further incrementing the refcount. - * - * Here, for that overflow case, use the signed bit to count a little - * bit higher via unsigned math, and thus still get an accurate result. - */ - return ((unsigned int)page_ref_count(compound_head(page))) >= - GUP_PIN_COUNTING_BIAS; -} - static inline bool is_cow_mapping(vm_flags_t flags) { return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; } -/* - * This should most likely only be called during fork() to see whether we - * should break the cow immediately for a page on the src mm. - */ -static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, - struct page *page) -{ - if (!is_cow_mapping(vma->vm_flags)) - return false; - - if (!test_bit(MMF_HAS_PINNED, &vma->vm_mm->flags)) - return false; - - return page_maybe_dma_pinned(page); -} - #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define SECTION_IN_PAGE_FLAGS #endif @@ -1549,6 +1483,69 @@ static inline atomic_t *folio_pincount_ptr(struct folio *folio) return &folio_page(folio, 1)->compound_pincount; } +/** + * folio_maybe_dma_pinned - Report if a folio may be pinned for DMA. + * @folio: The folio. + * + * This function checks if a folio has been pinned via a call to + * a function in the pin_user_pages() family. + * + * For small folios, the return value is partially fuzzy: false is not fuzzy, + * because it means "definitely not pinned for DMA", but true means "probably + * pinned for DMA, but possibly a false positive due to having at least + * GUP_PIN_COUNTING_BIAS worth of normal folio references". + * + * False positives are OK, because: a) it's unlikely for a folio to + * get that many refcounts, and b) all the callers of this routine are + * expected to be able to deal gracefully with a false positive. + * + * For large folios, the result will be exactly correct. That's because + * we have more tracking data available: the compound_pincount is used + * instead of the GUP_PIN_COUNTING_BIAS scheme. + * + * For more information, please see Documentation/core-api/pin_user_pages.rst. + * + * Return: True, if it is likely that the page has been "dma-pinned". + * False, if the page is definitely not dma-pinned. + */ +static inline bool folio_maybe_dma_pinned(struct folio *folio) +{ + if (folio_test_large(folio)) + return atomic_read(folio_pincount_ptr(folio)) > 0; + + /* + * folio_ref_count() is signed. If that refcount overflows, then + * folio_ref_count() returns a negative value, and callers will avoid + * further incrementing the refcount. + * + * Here, for that overflow case, use the sign bit to count a little + * bit higher via unsigned math, and thus still get an accurate result. + */ + return ((unsigned int)folio_ref_count(folio)) >= + GUP_PIN_COUNTING_BIAS; +} + +static inline bool page_maybe_dma_pinned(struct page *page) +{ + return folio_maybe_dma_pinned(page_folio(page)); +} + +/* + * This should most likely only be called during fork() to see whether we + * should break the cow immediately for a page on the src mm. + */ +static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, + struct page *page) +{ + if (!is_cow_mapping(vma->vm_flags)) + return false; + + if (!test_bit(MMF_HAS_PINNED, &vma->vm_mm->flags)) + return false; + + return page_maybe_dma_pinned(page); +} + /* MIGRATE_CMA and ZONE_MOVABLE do not allow pin pages */ #ifdef CONFIG_MIGRATION static inline bool is_pinnable_page(struct page *page) |