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Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c43
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,