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mm/gup: Implement the dev_pagemap() logic in the generic get_user_pages_fast() function 

This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

Prepare generic GUP_fast() to handle dev_pagemap(). At the moment, it's
only implemented on x86. On non-x86, the new code will be compiled out.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-6-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Kirill A. Shutemov 2017-03-16 18:26:53 +03:00 committed by Ingo Molnar
parent e93480537f
commit b59f65fa07
2 changed files with 89 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/mm.h
View File

@ -430,6 +430,10 @@ static inline int pud_devmap(pud_t pud)
{
return 0;
}
static inline int pgd_devmap(pgd_t pgd)
{
return 0;
}
#endif
/*

87
mm/gup.c
View File

@ -1200,12 +1200,23 @@ static inline pte_t gup_get_pte(pte_t *ptep)
}
#endif
static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages)
{
while ((*nr) - nr_start) {
struct page *page = pages[--(*nr)];
ClearPageReferenced(page);
put_page(page);
}
}
#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)
{
struct dev_pagemap *pgmap = NULL;
int nr_start = *nr, ret = 0;
pte_t *ptep, *ptem;
int ret = 0;
ptem = ptep = pte_offset_map(&pmd, addr);
do {
@ -1222,7 +1233,13 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
if (!pte_access_permitted(pte, write))
goto pte_unmap;
if (pte_special(pte))
if (pte_devmap(pte)) {
pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, pages);
goto pte_unmap;
}
} else if (pte_special(pte))
goto pte_unmap;
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
@ -1239,6 +1256,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
VM_BUG_ON_PAGE(compound_head(page) != head, page);
put_dev_pagemap(pgmap);
SetPageReferenced(page);
pages[*nr] = page;
(*nr)++;
@ -1269,6 +1287,64 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
}
#endif /* __HAVE_ARCH_PTE_SPECIAL */
#ifdef __HAVE_ARCH_PTE_DEVMAP
static int __gup_device_huge(unsigned long pfn, unsigned long addr,
unsigned long end, struct page **pages, int *nr)
{
int nr_start = *nr;
struct dev_pagemap *pgmap = NULL;
do {
struct page *page = pfn_to_page(pfn);
pgmap = get_dev_pagemap(pfn, pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, pages);
return 0;
}
SetPageReferenced(page);
pages[*nr] = page;
get_page(page);
put_dev_pagemap(pgmap);
(*nr)++;
pfn++;
} while (addr += PAGE_SIZE, addr != end);
return 1;
}
static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,
unsigned long end, struct page **pages, int *nr)
{
unsigned long fault_pfn;
fault_pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
return __gup_device_huge(fault_pfn, addr, end, pages, nr);
}
static int __gup_device_huge_pud(pud_t pud, unsigned long addr,
unsigned long end, struct page **pages, int *nr)
{
unsigned long fault_pfn;
fault_pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
return __gup_device_huge(fault_pfn, addr, end, pages, nr);
}
#else
static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,
unsigned long end, struct page **pages, int *nr)
{
BUILD_BUG();
return 0;
}
static int __gup_device_huge_pud(pud_t pud, unsigned long addr,
unsigned long end, struct page **pages, int *nr)
{
BUILD_BUG();
return 0;
}
#endif
static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
@ -1278,6 +1354,9 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (!pmd_access_permitted(orig, write))
return 0;
if (pmd_devmap(orig))
return __gup_device_huge_pmd(orig, addr, end, pages, nr);
refs = 0;
head = pmd_page(orig);
page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
@ -1314,6 +1393,9 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
if (!pud_access_permitted(orig, write))
return 0;
if (pud_devmap(orig))
return __gup_device_huge_pud(orig, addr, end, pages, nr);
refs = 0;
head = pud_page(orig);
page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
@ -1351,6 +1433,7 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
if (!pgd_access_permitted(orig, write))
return 0;
BUILD_BUG_ON(pgd_devmap(orig));
refs = 0;
head = pgd_page(orig);
page = head + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);