Commit-ID: 0005d20b2ff1e501e186b3b3bc587085ac305fdc Gitweb: http://git.kernel.org/tip/0005d20b2ff1e501e186b3b3bc587085ac305fdc Author: Kirill A. Shutemov <[email protected]> AuthorDate: Thu, 16 Mar 2017 18:26:51 +0300 Committer: Ingo Molnar <[email protected]> CommitDate: Sat, 18 Mar 2017 09:48:02 +0100
mm/gup: Move page table entry dereference into helper function This is a preparation patch for the transition of x86 to the generic GUP_fast() implementation. On x86 PAE, page table entry is larger than sizeof(long) and we would need to provide a helper that can read the entry atomically. Signed-off-by: Kirill A. Shutemov <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Aneesh Kumar K . V <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Dann Frazier <[email protected]> Cc: Dave Hansen <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Steve Capper <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- mm/gup.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index a62a778c..e83db38 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1189,6 +1189,17 @@ struct page *get_dump_page(unsigned long addr) */ #ifdef CONFIG_HAVE_GENERIC_RCU_GUP +#ifndef gup_get_pte +/* + * We assume that the PTE can be read atomically. If this is not the case for + * your architecture, please provide the helper. + */ +static inline pte_t gup_get_pte(pte_t *ptep) +{ + return READ_ONCE(*ptep); +} +#endif + #ifdef __HAVE_ARCH_PTE_SPECIAL static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) @@ -1198,14 +1209,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, ptem = ptep = pte_offset_map(&pmd, addr); do { - /* - * In the line below we are assuming that the pte can be read - * atomically. If this is not the case for your architecture, - * please wrap this in a helper function! - * - * for an example see gup_get_pte in arch/x86/mm/gup.c - */ - pte_t pte = READ_ONCE(*ptep); + pte_t pte = gup_get_pte(ptep); struct page *head, *page; /*
