Re: [PATCH 5/7] mm/gup: Implement dev_pagemap logic in generic get_user_pages_fast()

From: Kirill A. Shutemov
Date: Fri Mar 17 2017 - 13:27:31 EST


On Thu, Mar 16, 2017 at 06:26:53PM +0300, Kirill A. Shutemov wrote:
> +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);
> +}
> +

PowerPC doesn't [always] provide pmd_pfn() and pud_pfn().

Fixup:

diff --git a/mm/gup.c b/mm/gup.c
index 5cc489d98562..6f36cbc294cf 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1287,6 +1287,7 @@ 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)
{
@@ -1328,6 +1329,21 @@ static int __gup_device_huge_pud(pud_t pud, unsigned long addr,
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)
@@ -1338,7 +1354,6 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (!pmd_access_permitted(orig, write))
return 0;

- VM_BUG_ON(!pfn_valid(pmd_pfn(orig)));
if (pmd_devmap(orig))
return __gup_device_huge_pmd(orig, addr, end, pages, nr);

@@ -1378,7 +1393,6 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
if (!pud_access_permitted(orig, write))
return 0;

- VM_BUG_ON(!pfn_valid(pud_pfn(orig)));
if (pud_devmap(orig))
return __gup_device_huge_pud(orig, addr, end, pages, nr);

--
Kirill A. Shutemov