From 7af75561e17132b20b5bc047d222f34b3e7a3e6e Mon Sep 17 00:00:00 2001 From: Ira Weiny Date: Mon, 13 May 2019 17:17:14 -0700 Subject: [PATCH] mm/gup: add FOLL_LONGTERM capability to GUP fast DAX pages were previously unprotected from longterm pins when users called get_user_pages_fast(). Use the new FOLL_LONGTERM flag to check for DEVMAP pages and fall back to regular GUP processing if a DEVMAP page is encountered. [ira.weiny@intel.com: v3] Link: http://lkml.kernel.org/r/20190328084422.29911-5-ira.weiny@intel.com Link: http://lkml.kernel.org/r/20190328084422.29911-5-ira.weiny@intel.com Link: http://lkml.kernel.org/r/20190317183438.2057-5-ira.weiny@intel.com Signed-off-by: Ira Weiny Reviewed-by: Andrew Morton Cc: Aneesh Kumar K.V Cc: Benjamin Herrenschmidt Cc: Borislav Petkov Cc: Dan Williams Cc: "David S. Miller" Cc: Heiko Carstens Cc: Ingo Molnar Cc: James Hogan Cc: Jason Gunthorpe Cc: John Hubbard Cc: "Kirill A. Shutemov" Cc: Martin Schwidefsky Cc: Michal Hocko Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Ralf Baechle Cc: Rich Felker Cc: Thomas Gleixner Cc: Yoshinori Sato Cc: Mike Marshall Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/gup.c | 40 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 36 insertions(+), 4 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 3dde6a8da670..8e0a0a3a2b2d 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1637,6 +1637,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, goto pte_unmap; if (pte_devmap(pte)) { + if (unlikely(flags & FOLL_LONGTERM)) + goto pte_unmap; + pgmap = get_dev_pagemap(pte_pfn(pte), pgmap); if (unlikely(!pgmap)) { undo_dev_pagemap(nr, nr_start, pages); @@ -1776,8 +1779,11 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, if (!pmd_access_permitted(orig, flags & FOLL_WRITE)) return 0; - if (pmd_devmap(orig)) + if (pmd_devmap(orig)) { + if (unlikely(flags & FOLL_LONGTERM)) + return 0; return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr); + } refs = 0; page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); @@ -1814,8 +1820,11 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, if (!pud_access_permitted(orig, flags & FOLL_WRITE)) return 0; - if (pud_devmap(orig)) + if (pud_devmap(orig)) { + if (unlikely(flags & FOLL_LONGTERM)) + return 0; return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr); + } refs = 0; page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); @@ -2058,6 +2067,29 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, return nr; } +static int __gup_longterm_unlocked(unsigned long start, int nr_pages, + unsigned int gup_flags, struct page **pages) +{ + int ret; + + /* + * FIXME: FOLL_LONGTERM does not work with + * get_user_pages_unlocked() (see comments in that function) + */ + if (gup_flags & FOLL_LONGTERM) { + down_read(¤t->mm->mmap_sem); + ret = __gup_longterm_locked(current, current->mm, + start, nr_pages, + pages, NULL, gup_flags); + up_read(¤t->mm->mmap_sem); + } else { + ret = get_user_pages_unlocked(start, nr_pages, + pages, gup_flags); + } + + return ret; +} + /** * get_user_pages_fast() - pin user pages in memory * @start: starting user address @@ -2103,8 +2135,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, start += nr << PAGE_SHIFT; pages += nr; - ret = get_user_pages_unlocked(start, nr_pages - nr, pages, - gup_flags); + ret = __gup_longterm_unlocked(start, nr_pages - nr, + gup_flags, pages); /* Have to be a bit careful with return values */ if (nr > 0) { -- 2.30.2