From patchwork Thu Jun 13 09:55:29 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 10992473 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3D13514BB for ; Thu, 13 Jun 2019 15:39:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2CE43201A4 for ; Thu, 13 Jun 2019 15:39:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 21466204BF; Thu, 13 Jun 2019 15:39:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.7 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B124D201A4 for ; Thu, 13 Jun 2019 15:39:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726519AbfFMPjS (ORCPT ); Thu, 13 Jun 2019 11:39:18 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:38668 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731928AbfFMJzo (ORCPT ); Thu, 13 Jun 2019 05:55:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From :Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=se5RwgsJXpIaRwAJUDF3EubFPW97VYMOUZlHXB89uq8=; b=rV+MBzg7sqo1mUHED0579Ypk5t B23sAkHUq9mrkVlzB0ppko81oqmxrF1ziuEylJ2fyKgaHLCL2B013KzkonbpW4ZaE8r5+s/+xe1Zs HZHb0BOYKLbyeTE46Y0ATLJCPqTakmUJoJfSQNVh2K+RueFUpHQquEvNR/EPPgW8AuHepd3p7pDpL EeDetwgkooiRPjY6N0PQtT1nFh5Sf+M1sVp6ZHDcWpQLPnbOx5BwgU8M6jIhjUy9WNlIKUnzPeoRc +ws+mGBTZ7RG0fSo753w2xnYlaGnHzMnl+WUxB/WC6BmqvYgqGIwjSNCQRwMG7Fn+q0wBY6ubBk4r 2JRbp0zw==; Received: from mpp-cp1-natpool-1-198.ethz.ch ([82.130.71.198] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hbMSI-0008M0-1l; Thu, 13 Jun 2019 09:55:38 +0000 From: Christoph Hellwig To: Jens Axboe , Ming Lei Cc: David Gibson , "Darrick J. Wong" , linux-block@vger.kernel.org, linux-xfs@vger.kernel.org Subject: [PATCH 2/2] block: fix page leak when merging to same page Date: Thu, 13 Jun 2019 11:55:29 +0200 Message-Id: <20190613095529.25005-3-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190613095529.25005-1-hch@lst.de> References: <20190613095529.25005-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When multiple iovecs reference the same page, each get_user_page call will add a reference to the page. But once we've created the bio that information gets lost and only a single reference will be dropped after I/O completion. Use the same_page information returned from __bio_try_merge_page to drop additional references to pages that were already present in the bio. Based on a patch from Ming Lei. Link: https://lkml.org/lkml/2019/4/23/64 Fixes: 576ed913 ("block: use bio_add_page in bio_iov_iter_get_pages") Reported-by: David Gibson Signed-off-by: Christoph Hellwig Reviewed-by: Ming Lei --- block/bio.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/block/bio.c b/block/bio.c index 59588c57694d..35b3c568a48f 100644 --- a/block/bio.c +++ b/block/bio.c @@ -895,6 +895,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt; struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt; struct page **pages = (struct page **)bv; + bool same_page = false; ssize_t size, left; unsigned len, i; size_t offset; @@ -915,8 +916,15 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) struct page *page = pages[i]; len = min_t(size_t, PAGE_SIZE - offset, left); - if (WARN_ON_ONCE(bio_add_page(bio, page, len, offset) != len)) - return -EINVAL; + + if (__bio_try_merge_page(bio, page, len, offset, &same_page)) { + if (same_page) + put_page(page); + } else { + if (WARN_ON_ONCE(bio_full(bio))) + return -EINVAL; + __bio_add_page(bio, page, len, offset); + } offset = 0; }