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authorDan Williams <dan.j.williams@intel.com>2016-01-16 00:56:55 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-16 01:56:32 (GMT)
commit3565fce3a6597e91b8dee3e8e36ebf70f8b7ef9b (patch)
tree54f05861c87cb2c2710552b61a46cb5831b06296 /arch
parent5c7fb56e5e3f7035dd798a8e1adee639f87043e5 (diff)
downloadlinux-3565fce3a6597e91b8dee3e8e36ebf70f8b7ef9b.tar.xz
mm, x86: get_user_pages() for dax mappings
A dax mapping establishes a pte with _PAGE_DEVMAP set when the driver has established a devm_memremap_pages() mapping, i.e. when the pfn_t return from ->direct_access() has PFN_DEV and PFN_MAP set. Later, when encountering _PAGE_DEVMAP during a page table walk we lookup and pin a struct dev_pagemap instance to keep the result of pfn_to_page() valid until put_page(). Signed-off-by: Dan Williams <dan.j.williams@intel.com> Tested-by: Logan Gunthorpe <logang@deltatee.com> Cc: Dave Hansen <dave@sr71.net> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/pgtable.h7
-rw-r--r--arch/x86/mm/gup.c57
2 files changed, 61 insertions, 3 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 6a0ad82..0687c47 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -479,6 +479,13 @@ static inline int pte_present(pte_t a)
return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE);
}
+#ifdef __HAVE_ARCH_PTE_DEVMAP
+static inline int pte_devmap(pte_t a)
+{
+ return (pte_flags(a) & _PAGE_DEVMAP) == _PAGE_DEVMAP;
+}
+#endif
+
#define pte_accessible pte_accessible
static inline bool pte_accessible(struct mm_struct *mm, pte_t a)
{
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index f8cb3e8..6d5eb59 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -9,6 +9,7 @@
#include <linux/vmstat.h>
#include <linux/highmem.h>
#include <linux/swap.h>
+#include <linux/memremap.h>
#include <asm/pgtable.h>
@@ -63,6 +64,16 @@ retry:
#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);
+ }
+}
+
/*
* The performance critical leaf functions are made noinline otherwise gcc
* inlines everything into a single function which results in too much
@@ -71,7 +82,9 @@ retry:
static noinline 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;
unsigned long mask;
+ int nr_start = *nr;
pte_t *ptep;
mask = _PAGE_PRESENT|_PAGE_USER;
@@ -89,13 +102,21 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
return 0;
}
- if ((pte_flags(pte) & (mask | _PAGE_SPECIAL)) != mask) {
+ page = pte_page(pte);
+ if (pte_devmap(pte)) {
+ pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
+ if (unlikely(!pgmap)) {
+ undo_dev_pagemap(nr, nr_start, pages);
+ pte_unmap(ptep);
+ return 0;
+ }
+ } else if ((pte_flags(pte) & (mask | _PAGE_SPECIAL)) != mask) {
pte_unmap(ptep);
return 0;
}
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
- page = pte_page(pte);
get_page(page);
+ put_dev_pagemap(pgmap);
SetPageReferenced(page);
pages[*nr] = page;
(*nr)++;
@@ -114,6 +135,32 @@ static inline void get_head_page_multiple(struct page *page, int nr)
SetPageReferenced(page);
}
+static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,
+ unsigned long end, struct page **pages, int *nr)
+{
+ int nr_start = *nr;
+ unsigned long pfn = pmd_pfn(pmd);
+ struct dev_pagemap *pgmap = NULL;
+
+ pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
+ 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 noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
@@ -126,9 +173,13 @@ static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
mask |= _PAGE_RW;
if ((pmd_flags(pmd) & mask) != mask)
return 0;
+
+ VM_BUG_ON(!pfn_valid(pmd_pfn(pmd)));
+ if (pmd_devmap(pmd))
+ return __gup_device_huge_pmd(pmd, addr, end, pages, nr);
+
/* hugepages are never "special" */
VM_BUG_ON(pmd_flags(pmd) & _PAGE_SPECIAL);
- VM_BUG_ON(!pfn_valid(pmd_pfn(pmd)));
refs = 0;
head = pmd_page(pmd);