In preparation for solving the dax-dma vs truncate race, disable
get_user_pages_fast(). The race fix relies on the vma being available.
We can still support get_user_pages_fast() for 1GB (pud) 'devmap'
mappings since those are only implemented for device-dax, everything
else needs the vma and the gup-slow-path in case it might be a
filesytem-dax mapping.
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
mm/gup.c | 48 +++++++++++++-----------------------------------
1 file changed, 13 insertions(+), 35 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index b2b4d4263768..308be897d22a 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1290,22 +1290,12 @@ 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;
+ int ret = 0;
pte_t *ptep, *ptem;
ptem = ptep = pte_offset_map(&pmd, addr);
@@ -1323,13 +1313,7 @@ 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_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))
+ if (pte_devmap(pte) || (pte_special(pte)))
goto pte_unmap;
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
@@ -1378,6 +1362,16 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
#endif /* __HAVE_ARCH_PTE_SPECIAL */
#if defined(__HAVE_ARCH_PTE_DEVMAP) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
+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);
+ }
+}
+
static int __gup_device_huge(unsigned long pfn, unsigned long addr,
unsigned long end, struct page **pages, int *nr)
{
@@ -1402,15 +1396,6 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
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)
{
@@ -1420,13 +1405,6 @@ static int __gup_device_huge_pud(pud_t pud, unsigned long addr,
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)
{
@@ -1445,7 +1423,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
return 0;
if (pmd_devmap(orig))
- return __gup_device_huge_pmd(orig, addr, end, pages, nr);
+ return 0;
refs = 0;
page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
--
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