From patchwork Mon Mar 15 13:55:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 401167 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_RED, 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 ED316C2BA13 for ; Mon, 15 Mar 2021 14:09:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A75F664E86 for ; Mon, 15 Mar 2021 14:09:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232167AbhCOOJa (ORCPT ); Mon, 15 Mar 2021 10:09:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:50816 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233001AbhCOOD6 (ORCPT ); Mon, 15 Mar 2021 10:03:58 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7A26364E83; Mon, 15 Mar 2021 14:03:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615817037; bh=WwPBGAYBGzs6XzBbiI6mldC2Tgnb08UZi4a5Wx6imh0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ShRUOaaf2wdFZOjgrGJt8QisUa4V+0Aso6OIjElObKfS5SRu1fwpPVGQG+lB3vMus fkfvLtY+pv7bUr6smu/EkOAlQEmkKR4LQyQ/L4KUF8FOnP+rKpxYVnfbCw0NZprc6Y 5pF01Swpzk7Aq26jfwERTri9tN70RJXBJUYyeuYA= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Minchan Kim , Amos Bianchi , Sergey Senozhatsky , John Dias , Andrew Morton , Linus Torvalds Subject: [PATCH 5.11 270/306] zram: fix broken page writeback Date: Mon, 15 Mar 2021 14:55:33 +0100 Message-Id: <20210315135516.787087270@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135507.611436477@linuxfoundation.org> References: <20210315135507.611436477@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Greg Kroah-Hartman From: Minchan Kim commit 2766f1821600cc7562bae2128ad0b163f744c5d9 upstream. commit 0d8359620d9b ("zram: support page writeback") introduced two problems. It overwrites writeback_store's return value as kstrtol's return value, which makes return value zero so user could see zero as return value of write syscall even though it wrote data successfully. It also breaks index value in the loop in that it doesn't increase the index any longer. It means it can write only first starting block index so user couldn't write all idle pages in the zram so lose memory saving chance. This patch fixes those issues. Link: https://lkml.kernel.org/r/20210312173949.2197662-2-minchan@kernel.org Fixes: 0d8359620d9b("zram: support page writeback") Signed-off-by: Minchan Kim Reported-by: Amos Bianchi Cc: Sergey Senozhatsky Cc: John Dias Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/block/zram/zram_drv.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -639,8 +639,8 @@ static ssize_t writeback_store(struct de if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1)) return -EINVAL; - ret = kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index); - if (ret || index >= nr_pages) + if (kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index) || + index >= nr_pages) return -EINVAL; nr_pages = 1; @@ -664,7 +664,7 @@ static ssize_t writeback_store(struct de goto release_init_lock; } - while (nr_pages--) { + for (; nr_pages != 0; index++, nr_pages--) { struct bio_vec bvec; bvec.bv_page = page;