Merge git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next

[~andy/linux] / mm / hugetlb.c

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7acd12503f734bfcaff2c4fed244e594952962ea..ea8c3a4cd2ae8acdf52a7a4e862e277f2390c265 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -800,7 +800,7 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
 
        if (page && arch_prepare_hugepage(page)) {
                __free_pages(page, huge_page_order(h));
-               return NULL;
+               page = NULL;
        }
 
        spin_lock(&hugetlb_lock);
@@ -2315,8 +2315,7 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
         * from page cache lookup which is in HPAGE_SIZE units.
         */
        address = address & huge_page_mask(h);
-       pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
-               + (vma->vm_pgoff >> PAGE_SHIFT);
+       pgoff = vma_hugecache_offset(h, vma, address);
        mapping = (struct address_space *)page_private(page);
 
        /*
@@ -2349,6 +2348,9 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
 
 /*
  * Hugetlb_cow() should be called with page lock of the original hugepage held.
+ * Called with hugetlb_instantiation_mutex held and pte_page locked so we
+ * cannot race with other handlers or page migration.
+ * Keep the pte_same checks anyway to make transition from the mutex easier.
  */
 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
                        unsigned long address, pte_t *ptep, pte_t pte,
@@ -2408,7 +2410,14 @@ retry_avoidcopy:
                                BUG_ON(page_count(old_page) != 1);
                                BUG_ON(huge_pte_none(pte));
                                spin_lock(&mm->page_table_lock);
-                               goto retry_avoidcopy;
+                               ptep = huge_pte_offset(mm, address & huge_page_mask(h));
+                               if (likely(pte_same(huge_ptep_get(ptep), pte)))
+                                       goto retry_avoidcopy;
+                               /*
+                                * race occurs while re-acquiring page_table_lock, and
+                                * our job is done.
+                                */
+                               return 0;
                        }
                        WARN_ON_ONCE(1);
                }
@@ -2630,6 +2639,8 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
        static DEFINE_MUTEX(hugetlb_instantiation_mutex);
        struct hstate *h = hstate_vma(vma);
 
+       address &= huge_page_mask(h);
+
        ptep = huge_pte_offset(mm, address);
        if (ptep) {
                entry = huge_ptep_get(ptep);