summaryrefslogtreecommitdiffstats
path: root/mm
diff options
context:
space:
mode:
Diffstat (limited to 'mm')
-rw-r--r--mm/hugetlb.c21
1 files changed, 10 insertions, 11 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 87fd3ab809c6..e37efd5d8318 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3755,16 +3755,16 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
}
/*
- * Use page lock to guard against racing truncation
- * before we get page_table_lock.
+ * We can not race with truncation due to holding i_mmap_rwsem.
+ * Check once here for faults beyond end of file.
*/
+ size = i_size_read(mapping->host) >> huge_page_shift(h);
+ if (idx >= size)
+ goto out;
+
retry:
page = find_lock_page(mapping, idx);
if (!page) {
- size = i_size_read(mapping->host) >> huge_page_shift(h);
- if (idx >= size)
- goto out;
-
/*
* Check for page in userfault range
*/
@@ -3854,9 +3854,6 @@ retry:
}
ptl = huge_pte_lock(h, mm, ptep);
- size = i_size_read(mapping->host) >> huge_page_shift(h);
- if (idx >= size)
- goto backout;
ret = 0;
if (!huge_pte_none(huge_ptep_get(ptep)))
@@ -3959,8 +3956,10 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
/*
* Acquire i_mmap_rwsem before calling huge_pte_alloc and hold
- * until finished with ptep. This prevents huge_pmd_unshare from
- * being called elsewhere and making the ptep no longer valid.
+ * until finished with ptep. This serves two purposes:
+ * 1) It prevents huge_pmd_unshare from being called elsewhere
+ * and making the ptep no longer valid.
+ * 2) It synchronizes us with file truncation.
*
* ptep could have already be assigned via huge_pte_offset. That
* is OK, as huge_pte_alloc will return the same value unless