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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id d4si65261819pfa.150.2019.01.07.12.02.29 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 07 Jan 2019 12:02:29 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=oBzkRlX7; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Message-Id:Date:Subject:Cc:To:From: Sender:Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=L2csFkuIpaJFSD1R4XQC20uR44/yfYBbN7aqwGxOgyU=; b=oBzkRlX7xTW5/t1XtBRxZj5rK 0t4q3oP84C8TlYEhQA27GQZmgEBlWaRwYwmssd8McxRlW7jXyApnzWqb76naYCTf23pTXL0TIPcxl G2iS/EXKd/WENZU9xHPpA7q13PHV6QUMd6WdAElUnj69AZIU3sACm2tO8y6bj9XVGvs5uBbhfC5vJ VNEPuSME+Lw84E3OOTbqiV+qBddxzoU9ztnVclCSlE7fOtg8LACJRFtIgohCyz+D1Y4D0euVhIO0z LYxd0uFtk/uA8JwCgNHDqbQRj5h8Gz9lzIN+sNGE3MlIYoRrOHJKfQofaLUP/5hj9Ry9JFCQaXRpW 6gl7o5zRQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1ggb6R-0003Vg-Ho; Mon, 07 Jan 2019 20:02:28 +0000 From: Matthew Wilcox To: Andrew Morton , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Matthew Wilcox Subject: [PATCH] mm: Remove redundant test from find_get_pages_contig Date: Mon, 7 Jan 2019 12:02:24 -0800 Message-Id: <20190107200224.13260-1-willy@infradead.org> X-Mailer: git-send-email 2.14.5 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP 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 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 9f5e323e883e6..935fbc29aeb13 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1837,16 +1837,6 @@ 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;