提交 9cbb4cb2 编写于 作者: N Nick Piggin 提交者: Linus Torvalds

mm: find_get_pages_contig fixlet

Testing ->mapping and ->index without a ref is not stable as the page
may have been reused at this point.
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
Reviewed-by: NWu Fengguang <fengguang.wu@intel.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 f0bc0a60
......@@ -837,9 +837,6 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
if (radix_tree_deref_retry(page))
goto restart;
if (page->mapping == NULL || page->index != index)
break;
if (!page_cache_get_speculative(page))
goto repeat;
......@@ -849,6 +846,16 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
goto repeat;
}
/*
* must check mapping and index after taking the ref.
* otherwise we can get both false positives and false
* negatives, which is just confusing to the caller.
*/
if (page->mapping == NULL || page->index != index) {
page_cache_release(page);
break;
}
pages[ret] = page;
ret++;
index++;
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册