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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 654BFC433E2 for ; Sun, 30 Aug 2020 01:08:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 379D02075B for ; Sun, 30 Aug 2020 01:08:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728589AbgH3BIk (ORCPT ); Sat, 29 Aug 2020 21:08:40 -0400 Received: from mail.parknet.co.jp ([210.171.160.6]:33438 "EHLO mail.parknet.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728246AbgH3BIj (ORCPT ); Sat, 29 Aug 2020 21:08:39 -0400 X-Greylist: delayed 536 seconds by postgrey-1.27 at vger.kernel.org; Sat, 29 Aug 2020 21:08:39 EDT Received: from ibmpc.myhome.or.jp (server.parknet.ne.jp [210.171.168.39]) by mail.parknet.co.jp (Postfix) with ESMTPSA id 1FDB81B44DF; Sun, 30 Aug 2020 09:59:43 +0900 (JST) Received: from devron.myhome.or.jp (foobar@devron.myhome.or.jp [192.168.0.3]) by ibmpc.myhome.or.jp (8.15.2/8.15.2/Debian-20) with ESMTPS id 07U0xf8Y321806 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Sun, 30 Aug 2020 09:59:42 +0900 Received: from devron.myhome.or.jp (foobar@localhost [127.0.0.1]) by devron.myhome.or.jp (8.15.2/8.15.2/Debian-20) with ESMTPS id 07U0xf0f3060830 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Sun, 30 Aug 2020 09:59:41 +0900 Received: (from hirofumi@localhost) by devron.myhome.or.jp (8.15.2/8.15.2/Submit) id 07U0xfPW3060829; Sun, 30 Aug 2020 09:59:41 +0900 From: OGAWA Hirofumi To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH] fat: Avoid oops when bdi->io_pages==0 Date: Sun, 30 Aug 2020 09:59:41 +0900 Message-ID: <87ft85osn6.fsf@mail.parknet.co.jp> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On one system, there was bdi->io_pages==0. This seems to be the bug of a driver somewhere, and should fix it though. Anyway, it is better to avoid the divide-by-zero Oops. So this check it. Signed-off-by: OGAWA Hirofumi Cc: --- fs/fat/fatent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c index f7e3304..98a1c4f 100644 --- a/fs/fat/fatent.c 2020-08-30 06:52:47.251564566 +0900 +++ b/fs/fat/fatent.c 2020-08-30 06:54:05.838319213 +0900 @@ -660,7 +660,7 @@ static void fat_ra_init(struct super_blo if (fatent->entry >= ent_limit) return; - if (ra_pages > sb->s_bdi->io_pages) + if (sb->s_bdi->io_pages && ra_pages > sb->s_bdi->io_pages) ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages); reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1); _ -- OGAWA Hirofumi