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Diffstat (limited to 'mm')
-rw-r--r--mm/hugetlb.c26
1 files changed, 19 insertions, 7 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0aee2f3ae15c..2480ba627aa5 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5241,6 +5241,21 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
VM_BUG_ON(unshare && (flags & FOLL_WRITE));
VM_BUG_ON(!unshare && !(flags & FOLL_WRITE));
+ /*
+ * hugetlb does not support FOLL_FORCE-style write faults that keep the
+ * PTE mapped R/O such as maybe_mkwrite() would do.
+ */
+ if (WARN_ON_ONCE(!unshare && !(vma->vm_flags & VM_WRITE)))
+ return VM_FAULT_SIGSEGV;
+
+ /* Let's take out MAP_SHARED mappings first. */
+ if (vma->vm_flags & VM_MAYSHARE) {
+ if (unlikely(unshare))
+ return 0;
+ set_huge_ptep_writable(vma, haddr, ptep);
+ return 0;
+ }
+
pte = huge_ptep_get(ptep);
old_page = pte_page(pte);
@@ -5781,12 +5796,11 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
* If we are going to COW/unshare the mapping later, we examine the
* pending reservations for this page now. This will ensure that any
* allocations necessary to record that reservation occur outside the
- * spinlock. For private mappings, we also lookup the pagecache
- * page now as it is used to determine if a reservation has been
- * consumed.
+ * spinlock. Also lookup the pagecache page now as it is used to
+ * determine if a reservation has been consumed.
*/
if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
- !huge_pte_write(entry)) {
+ !(vma->vm_flags & VM_MAYSHARE) && !huge_pte_write(entry)) {
if (vma_needs_reservation(h, vma, haddr) < 0) {
ret = VM_FAULT_OOM;
goto out_mutex;
@@ -5794,9 +5808,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
/* Just decrements count, does not deallocate */
vma_end_reservation(h, vma, haddr);
- if (!(vma->vm_flags & VM_MAYSHARE))
- pagecache_page = hugetlbfs_pagecache_page(h,
- vma, haddr);
+ pagecache_page = hugetlbfs_pagecache_page(h, vma, haddr);
}
ptl = huge_pte_lock(h, mm, ptep);