From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Matthew Wilcox To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Hugh Dickins , Matthew Wilcox Subject: [PATCH 1/2] mm: Remove redundant test from find_get_pages_contig Date: Thu, 22 Nov 2018 13:32:23 -0800 Message-Id: <20181122213224.12793-2-willy@infradead.org> In-Reply-To: <20181122213224.12793-1-willy@infradead.org> References: <20181122213224.12793-1-willy@infradead.org> Sender: owner-linux-mm@kvack.org List-ID: After we establish a reference on the page, we check the pointer continues to be in the correct position in i_pages. There's no need to check the page->mapping or page->index afterwards; if those can change after we've got the reference, they can change after we return the page to the caller. Signed-off-by: Matthew Wilcox --- mm/filemap.c | 10 ---------- 1 file changed, 10 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 81adec8ee02cc..538531590ef2d 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1776,16 +1776,6 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, if (unlikely(page != xas_reload(&xas))) goto put_page; - /* - * 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 || page_to_pgoff(page) != xas.xa_index) { - put_page(page); - break; - } - pages[ret] = page; if (++ret == nr_pages) break; -- 2.19.1