Re: [RFC PATCH v2 10/19] mm/gup: Pass a NULL vaddr_pin through GUP fast

John Hubbard
2019-08-10T00:07:04Z

On 8/9/19 3:58 PM, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> Internally GUP fast needs to know that fast users will not support file
> pins. Pass NULL for vaddr_pin through the fast call stack so that the
> pin code can return an error if it encounters file backed memory within
> the address range.
>

Reviewed-by: John Hubbard <jhubbard@nvidia.com>

thanks,
--
John Hubbard
NVIDIA

> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
> mm/gup.c | 65 ++++++++++++++++++++++++++++++++++----------------------
> 1 file changed, 40 insertions(+), 25 deletions(-)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index 7a449500f0a6..504af3e9a942 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1813,7 +1813,8 @@ static inline struct page *try_get_compound_head(struct page *page, int refs)
>
> #ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
> static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
> - unsigned int flags, struct page **pages, int *nr)
> + unsigned int flags, struct page **pages, int *nr,
> + struct vaddr_pin *vaddr_pin)
> {
> struct dev_pagemap *pgmap = NULL;
> int nr_start = *nr, ret = 0;
> @@ -1894,7 +1895,8 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
> * useful to have gup_huge_pmd even if we can't operate on ptes.
> */
> static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
> - unsigned int flags, struct page **pages, int *nr)
> + unsigned int flags, struct page **pages, int *nr,
> + struct vaddr_pin *vaddr_pin)
> {
> return 0;
> }
> @@ -1903,7 +1905,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
> #if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
> static int __gup_device_huge(unsigned long pfn, unsigned long addr,
> unsigned long end, struct page **pages, int *nr,
> - unsigned int flags)
> + unsigned int flags, struct vaddr_pin *vaddr_pin)
> {
> int nr_start = *nr;
> struct dev_pagemap *pgmap = NULL;
> @@ -1938,13 +1940,14 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
>
> static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
> unsigned long end, struct page **pages, int *nr,
> - unsigned int flags)
> + unsigned int flags, struct vaddr_pin *vaddr_pin)
> {
> unsigned long fault_pfn;
> int nr_start = *nr;
>
> fault_pfn = pmd_pfn(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
> - if (!__gup_device_huge(fault_pfn, addr, end, pages, nr, flags))
> + if (!__gup_device_huge(fault_pfn, addr, end, pages, nr, flags,
> + vaddr_pin))
> return 0;
>
> if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
> @@ -1957,13 +1960,14 @@ static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
>
> static int __gup_device_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
> unsigned long end, struct page **pages, int *nr,
> - unsigned int flags)
> + unsigned int flags, struct vaddr_pin *vaddr_pin)
> {
> unsigned long fault_pfn;
> int nr_start = *nr;
>
> fault_pfn = pud_pfn(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
> - if (!__gup_device_huge(fault_pfn, addr, end, pages, nr, flags))
> + if (!__gup_device_huge(fault_pfn, addr, end, pages, nr, flags,
> + vaddr_pin))
> return 0;
>
> if (unlikely(pud_val(orig) != pud_val(*pudp))) {
> @@ -1975,7 +1979,7 @@ static int __gup_device_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
> #else
> static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
> unsigned long end, struct page **pages, int *nr,
> - unsigned int flags)
> + unsigned int flags, struct vaddr_pin *vaddr_pin)
> {
> BUILD_BUG();
> return 0;
> @@ -1983,7 +1987,7 @@ static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
>
> static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr,
> unsigned long end, struct page **pages, int *nr,
> - unsigned int flags)
> + unsigned int flags, struct vaddr_pin *vaddr_pin)
> {
> BUILD_BUG();
> return 0;
> @@ -2075,7 +2079,8 @@ static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
> #endif /* CONFIG_ARCH_HAS_HUGEPD */
>
> static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
> - unsigned long end, unsigned int flags, struct page **pages, int *nr)
> + unsigned long end, unsigned int flags, struct page **pages,
> + int *nr, struct vaddr_pin *vaddr_pin)
> {
> struct page *head, *page;
> int refs;
> @@ -2087,7 +2092,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
> if (unlikely(flags & FOLL_LONGTERM))
> return 0;
> return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr,
> - flags);
> + flags, vaddr_pin);
> }
>
> refs = 0;
> @@ -2117,7 +2122,8 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
> }
>
> static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
> - unsigned long end, unsigned int flags, struct page **pages, int *nr)
> + unsigned long end, unsigned int flags, struct page **pages, int *nr,
> + struct vaddr_pin *vaddr_pin)
> {
> struct page *head, *page;
> int refs;
> @@ -2129,7 +2135,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
> if (unlikely(flags & FOLL_LONGTERM))
> return 0;
> return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr,
> - flags);
> + flags, vaddr_pin);
> }
>
> refs = 0;
> @@ -2196,7 +2202,8 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
> }
>
> static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
> - unsigned int flags, struct page **pages, int *nr)
> + unsigned int flags, struct page **pages, int *nr,
> + struct vaddr_pin *vaddr_pin)
> {
> unsigned long next;
> pmd_t *pmdp;
> @@ -2220,7 +2227,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
> return 0;
>
> if (!gup_huge_pmd(pmd, pmdp, addr, next, flags,
> - pages, nr))
> + pages, nr, vaddr_pin))
> return 0;
>
> } else if (unlikely(is_hugepd(__hugepd(pmd_val(pmd))))) {
> @@ -2231,7 +2238,8 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
> if (!gup_huge_pd(__hugepd(pmd_val(pmd)), addr,
> PMD_SHIFT, next, flags, pages, nr))
> return 0;
> - } else if (!gup_pte_range(pmd, addr, next, flags, pages, nr))
> + } else if (!gup_pte_range(pmd, addr, next, flags, pages, nr,
> + vaddr_pin))
> return 0;
> } while (pmdp++, addr = next, addr != end);
>
> @@ -2239,7 +2247,8 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
> }
>
> static int gup_pud_range(p4d_t p4d, unsigned long addr, unsigned long end,
> - unsigned int flags, struct page **pages, int *nr)
> + unsigned int flags, struct page **pages, int *nr,
> + struct vaddr_pin *vaddr_pin)
> {
> unsigned long next;
> pud_t *pudp;
> @@ -2253,13 +2262,14 @@ static int gup_pud_range(p4d_t p4d, unsigned long addr, unsigned long end,
> return 0;
> if (unlikely(pud_huge(pud))) {
> if (!gup_huge_pud(pud, pudp, addr, next, flags,
> - pages, nr))
> + pages, nr, vaddr_pin))
> return 0;
> } else if (unlikely(is_hugepd(__hugepd(pud_val(pud))))) {
> if (!gup_huge_pd(__hugepd(pud_val(pud)), addr,
> PUD_SHIFT, next, flags, pages, nr))
> return 0;
> - } else if (!gup_pmd_range(pud, addr, next, flags, pages, nr))
> + } else if (!gup_pmd_range(pud, addr, next, flags, pages, nr,
> + vaddr_pin))
> return 0;
> } while (pudp++, addr = next, addr != end);
>
> @@ -2267,7 +2277,8 @@ static int gup_pud_range(p4d_t p4d, unsigned long addr, unsigned long end,
> }
>
> static int gup_p4d_range(pgd_t pgd, unsigned long addr, unsigned long end,
> - unsigned int flags, struct page **pages, int *nr)
> + unsigned int flags, struct page **pages, int *nr,
> + struct vaddr_pin *vaddr_pin)
> {
> unsigned long next;
> p4d_t *p4dp;
> @@ -2284,7 +2295,8 @@ static int gup_p4d_range(pgd_t pgd, unsigned long addr, unsigned long end,
> if (!gup_huge_pd(__hugepd(p4d_val(p4d)), addr,
> P4D_SHIFT, next, flags, pages, nr))
> return 0;
> - } else if (!gup_pud_range(p4d, addr, next, flags, pages, nr))
> + } else if (!gup_pud_range(p4d, addr, next, flags, pages, nr,
> + vaddr_pin))
> return 0;
> } while (p4dp++, addr = next, addr != end);
>
> @@ -2292,7 +2304,8 @@ static int gup_p4d_range(pgd_t pgd, unsigned long addr, unsigned long end,
> }
>
> static void gup_pgd_range(unsigned long addr, unsigned long end,
> - unsigned int flags, struct page **pages, int *nr)
> + unsigned int flags, struct page **pages, int *nr,
> + struct vaddr_pin *vaddr_pin)
> {
> unsigned long next;
> pgd_t *pgdp;
> @@ -2312,7 +2325,8 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
> if (!gup_huge_pd(__hugepd(pgd_val(pgd)), addr,
> PGDIR_SHIFT, next, flags, pages, nr))
> return;
> - } else if (!gup_p4d_range(pgd, addr, next, flags, pages, nr))
> + } else if (!gup_p4d_range(pgd, addr, next, flags, pages, nr,
> + vaddr_pin))
> return;
> } while (pgdp++, addr = next, addr != end);
> }
> @@ -2374,7 +2388,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
> if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
> gup_fast_permitted(start, end)) {
> local_irq_save(flags);
> - gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
> + gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr,
> + NULL);
> local_irq_restore(flags);
> }
>
> @@ -2445,7 +2460,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
> if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
> gup_fast_permitted(start, end)) {
> local_irq_disable();
> - gup_pgd_range(addr, end, gup_flags, pages, &nr);
> + gup_pgd_range(addr, end, gup_flags, pages, &nr, NULL);
> local_irq_enable();
> ret = nr;
> }
>