From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 630D7C48BD6 for ; Thu, 27 Jun 2019 00:34:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 35DA421850 for ; Thu, 27 Jun 2019 00:34:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561595687; bh=O0ULjoFzCNvZzXuW9GRqTXu/TYfN84Zp6g+9mIEnPNE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bZC5IBTACP0aaPt6Sx2fbKx7AJltuyTsy0e3/JtKyQW/0ugSrUzb1a9sGbD/MlaF0 Y+gkbgiwYQe888mCercGqqbo+j2i5ZISMH8AfYnL5gEQhkfR+OSptIeuqLPoqhwP9f 7vieIkilu/l627t+nFjW/QJmrcW85Dc4wgbxCLBo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728126AbfF0Aep (ORCPT ); Wed, 26 Jun 2019 20:34:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:38972 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728113AbfF0Aem (ORCPT ); Wed, 26 Jun 2019 20:34:42 -0400 Received: from sasha-vm.mshome.net (unknown [107.242.116.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5EDD92184B; Thu, 27 Jun 2019 00:34:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561595681; bh=O0ULjoFzCNvZzXuW9GRqTXu/TYfN84Zp6g+9mIEnPNE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uQ+veMiCv2CNdGUElw8IUrjpKyELQByVsj50ff3eAOo/XhZl0mDywPKnsWW1gs+cH xfPzFnziegwHU8JPyHOJyC5I5HwOQ9QmXmB0K0Mxt/rXwLKTrRVXeXVwGhAPZcb0Fv HX4OUGED34OjsfIHs8LkiA4Swg9vvHnfgGkl1EF0= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Christoph Hellwig , David Gibson , Ming Lei , Jens Axboe , Sasha Levin , linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 5.1 77/95] block: fix page leak when merging to same page Date: Wed, 26 Jun 2019 20:30:02 -0400 Message-Id: <20190627003021.19867-77-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190627003021.19867-1-sashal@kernel.org> References: <20190627003021.19867-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christoph Hellwig [ Upstream commit 4569180495600ac59f5cd27f67242a6cb51254f3 ] 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 Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/bio.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/block/bio.c b/block/bio.c index a3c80a6c1fe5..80a25c245109 100644 --- a/block/bio.c +++ b/block/bio.c @@ -884,6 +884,7 @@ 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; @@ -904,8 +905,15 @@ 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; } -- 2.20.1