diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 43 |
1 files changed, 39 insertions, 4 deletions
diff --git a/mm/memory.c b/mm/memory.c index f9628e568c58..22e037e3364e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2180,6 +2180,42 @@ oom: return VM_FAULT_OOM; } +/* + * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED + * mapping + */ +static int wp_pfn_shared(struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long address, + pte_t *page_table, spinlock_t *ptl, pte_t orig_pte, + pmd_t *pmd) +{ + if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) { + struct vm_fault vmf = { + .page = NULL, + .pgoff = linear_page_index(vma, address), + .virtual_address = (void __user *)(address & PAGE_MASK), + .flags = FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE, + }; + int ret; + + pte_unmap_unlock(page_table, ptl); + ret = vma->vm_ops->pfn_mkwrite(vma, &vmf); + if (ret & VM_FAULT_ERROR) + return ret; + page_table = pte_offset_map_lock(mm, pmd, address, &ptl); + /* + * We might have raced with another page fault while we + * released the pte_offset_map_lock. + */ + if (!pte_same(*page_table, orig_pte)) { + pte_unmap_unlock(page_table, ptl); + return 0; + } + } + return wp_page_reuse(mm, vma, address, page_table, ptl, orig_pte, + NULL, 0, 0); +} + static int wp_page_shared(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pte_t *page_table, pmd_t *pmd, spinlock_t *ptl, pte_t orig_pte, @@ -2258,13 +2294,12 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, * VM_PFNMAP VMA. * * We should not cow pages in a shared writeable mapping. - * Just mark the pages writable as we can't do any dirty - * accounting on raw pfn maps. + * Just mark the pages writable and/or call ops->pfn_mkwrite. */ if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == (VM_WRITE|VM_SHARED)) - return wp_page_reuse(mm, vma, address, page_table, ptl, - orig_pte, old_page, 0, 0); + return wp_pfn_shared(mm, vma, address, page_table, ptl, + orig_pte, pmd); pte_unmap_unlock(page_table, ptl); return wp_page_copy(mm, vma, address, page_table, pmd, |