mm: meminit: make __early_pfn_to_nid SMP-safe and introduce meminit_pfn_in_nid

[firefly-linux-kernel-4.4.55.git] / mm / rmap.c

diff --git a/mm/rmap.c b/mm/rmap.c
index 24dd3f9fee27dfe577c7f605bd0c260f0bc143c7..171b68768df1478355bcddd5e30c2edd616ba05b 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -30,6 +30,8 @@
  *             swap_lock (in swap_duplicate, swap_info_get)
  *               mmlist_lock (in mmput, drain_mmlist and others)
  *               mapping->private_lock (in __set_page_dirty_buffers)
+ *                 mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
+ *                   mapping->tree_lock (widely used)
  *               inode->i_lock (in set_page_dirty's __mark_inode_dirty)
  *               bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
  *                 sb_lock (within inode_lock in fs/fs-writeback.c)
@@ -625,7 +627,7 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
 
        pmd = pmd_offset(pud, address);
        /*
-        * Some THP functions use the sequence pmdp_clear_flush(), set_pmd_at()
+        * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
         * without holding anon_vma lock for write.  So when looking for a
         * genuine pmde (in which to find pte), test present and !THP together.
         */
@@ -950,7 +952,12 @@ void page_move_anon_rmap(struct page *page,
        VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);
 
        anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
-       page->mapping = (struct address_space *) anon_vma;
+       /*
+        * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
+        * simultaneously, so a concurrent reader (eg page_referenced()'s
+        * PageAnon()) will not see one without the other.
+        */
+       WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
 }
 
 /**