diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2017-11-27 06:21:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-05 11:24:31 +0100 |
| commit | 7031ae2ab37d3df53c4a4e9903329a5d38c745ec (patch) | |
| tree | e7fafecee20f76d05b16581c92b2c2966ff7d063 /mm | |
| parent | 29bd7003134a3220119e7a75c4b06ac567f966e7 (diff) | |
mm, thp: Do not make page table dirty unconditionally in touch_p[mu]d()
commit a8f97366452ed491d13cf1e44241bc0b5740b1f0 upstream.
Currently, we unconditionally make page table dirty in touch_pmd().
It may result in false-positive can_follow_write_pmd().
We may avoid the situation, if we would only make the page table entry
dirty if caller asks for write access -- FOLL_WRITE.
The patch also changes touch_pud() in the same way.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Salvatore Bonaccorso: backport for 4.9:
- Adjust context
- Drop specific part for PUD-sized transparent hugepages. Support
for PUD-sized transparent hugepages was added in v4.11-rc1
]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/huge_memory.c | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8258e9eee806..3cae1dcf069c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -745,20 +745,15 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmd) + pmd_t *pmd, int flags) { pmd_t _pmd; - /* - * We should set the dirty bit only for FOLL_WRITE but for now - * the dirty bit in the pmd is meaningless. And if the dirty - * bit will become meaningful and we'll only set it with - * FOLL_WRITE, an atomic set_bit will be required on the pmd to - * set the young bit, instead of the current set_pmd_at. - */ - _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); + _pmd = pmd_mkyoung(*pmd); + if (flags & FOLL_WRITE) + _pmd = pmd_mkdirty(_pmd); if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, - pmd, _pmd, 1)) + pmd, _pmd, flags & FOLL_WRITE)) update_mmu_cache_pmd(vma, addr, pmd); } @@ -787,7 +782,7 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, return NULL; if (flags & FOLL_TOUCH) - touch_pmd(vma, addr, pmd); + touch_pmd(vma, addr, pmd, flags); /* * device mapped pages can only be returned if the @@ -1158,7 +1153,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, page = pmd_page(*pmd); VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); if (flags & FOLL_TOUCH) - touch_pmd(vma, addr, pmd); + touch_pmd(vma, addr, pmd, flags); if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { /* * We don't mlock() pte-mapped THPs. This way we can avoid |