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Date: Fri, 13 Nov 2015 17:06:44 -0700 From: Ross Zwisler <ross.zwisler@...ux.intel.com> To: linux-kernel@...r.kernel.org Cc: Ross Zwisler <ross.zwisler@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, "J. Bruce Fields" <bfields@...ldses.org>, "Theodore Ts'o" <tytso@....edu>, Alexander Viro <viro@...iv.linux.org.uk>, Andreas Dilger <adilger.kernel@...ger.ca>, Dan Williams <dan.j.williams@...el.com>, Dave Chinner <david@...morbit.com>, Ingo Molnar <mingo@...hat.com>, Jan Kara <jack@...e.com>, Jeff Layton <jlayton@...chiereds.net>, Matthew Wilcox <willy@...ux.intel.com>, Thomas Gleixner <tglx@...utronix.de>, linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, linux-nvdimm@...ts.01.org, x86@...nel.org, xfs@....sgi.com, Andrew Morton <akpm@...ux-foundation.org>, Matthew Wilcox <matthew.r.wilcox@...el.com>, Dave Hansen <dave.hansen@...ux.intel.com> Subject: [PATCH v2 05/11] mm: add follow_pte_pmd() Similar to follow_pte(), follow_pte_pmd() allows either a PTE leaf or a huge page PMD leaf to be found and returned. Signed-off-by: Ross Zwisler <ross.zwisler@...ux.intel.com> Suggested-by: Dave Hansen <dave.hansen@...ux.intel.com> --- include/linux/mm.h | 2 ++ mm/memory.c | 38 ++++++++++++++++++++++++++++++-------- 2 files changed, 32 insertions(+), 8 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 80001de..393441c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1166,6 +1166,8 @@ int copy_page_range(struct mm_struct *dst, struct mm_struct *src, struct vm_area_struct *vma); void unmap_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen, int even_cows); +int follow_pte_pmd(struct mm_struct *mm, unsigned long address, + pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp); int follow_pfn(struct vm_area_struct *vma, unsigned long address, unsigned long *pfn); int follow_phys(struct vm_area_struct *vma, unsigned long address, diff --git a/mm/memory.c b/mm/memory.c index deb679c..7f4090e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3512,8 +3512,8 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) } #endif /* __PAGETABLE_PMD_FOLDED */ -static int __follow_pte(struct mm_struct *mm, unsigned long address, - pte_t **ptepp, spinlock_t **ptlp) +static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address, + pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp) { pgd_t *pgd; pud_t *pud; @@ -3529,12 +3529,20 @@ static int __follow_pte(struct mm_struct *mm, unsigned long address, goto out; pmd = pmd_offset(pud, address); - VM_BUG_ON(pmd_trans_huge(*pmd)); - if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) - goto out; - /* We cannot handle huge page PFN maps. Luckily they don't exist. */ - if (pmd_huge(*pmd)) + if (pmd_huge(*pmd)) { + if (!pmdpp) + goto out; + + *ptlp = pmd_lock(mm, pmd); + if (pmd_huge(*pmd)) { + *pmdpp = pmd; + return 0; + } + spin_unlock(*ptlp); + } + + if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) goto out; ptep = pte_offset_map_lock(mm, pmd, address, ptlp); @@ -3557,9 +3565,23 @@ static inline int follow_pte(struct mm_struct *mm, unsigned long address, /* (void) is needed to make gcc happy */ (void) __cond_lock(*ptlp, - !(res = __follow_pte(mm, address, ptepp, ptlp))); + !(res = __follow_pte_pmd(mm, address, ptepp, NULL, + ptlp))); + return res; +} + +int follow_pte_pmd(struct mm_struct *mm, unsigned long address, + pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp) +{ + int res; + + /* (void) is needed to make gcc happy */ + (void) __cond_lock(*ptlp, + !(res = __follow_pte_pmd(mm, address, ptepp, pmdpp, + ptlp))); return res; } +EXPORT_SYMBOL(follow_pte_pmd); /** * follow_pfn - look up PFN at a user virtual address -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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