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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DC6DC77B75 for ; Mon, 22 May 2023 19:43:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235149AbjEVTnC (ORCPT ); Mon, 22 May 2023 15:43:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37224 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235137AbjEVTm7 (ORCPT ); Mon, 22 May 2023 15:42:59 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C028E6A for ; Mon, 22 May 2023 12:42:42 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E282762A47 for ; Mon, 22 May 2023 19:42:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA843C433D2; Mon, 22 May 2023 19:42:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684784559; bh=FW2ugkxW1F+fvXMDfPEAfROTBQzUMBbSyiwPDTSt0Og=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oP06y60KqMBiRufhNlnpPBXtrCWWD6282BbC2yySFLo/dzcc7xNmKvPuGjzWSOoA8 KWbbmwd9BL01NPVyEz2PMeojehQYx6PbJzWNi/gzoPi8JxG/wg9kk1nuhUSx5YmMEW 2yfImON7L5cqHKJPvP3a+cEKZZJPGuKItwB49LoY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Colin Ian King , Jens Axboe , Sasha Levin Subject: [PATCH 6.3 124/364] block, bfq: Fix division by zero error on zero wsum Date: Mon, 22 May 2023 20:07:09 +0100 Message-Id: <20230522190415.897379399@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230522190412.801391872@linuxfoundation.org> References: <20230522190412.801391872@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Colin Ian King [ Upstream commit e53413f8deedf738a6782cc14cc00bd5852ccf18 ] When the weighted sum is zero the calculation of limit causes a division by zero error. Fix this by continuing to the next level. This was discovered by running as root: stress-ng --ioprio 0 Fixes divison by error oops: [ 521.450556] divide error: 0000 [#1] SMP NOPTI [ 521.450766] CPU: 2 PID: 2684464 Comm: stress-ng-iopri Not tainted 6.2.1-1280.native #1 [ 521.451117] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.1-0-g3208b098f51a-prebuilt.qemu.org 04/01/2014 [ 521.451627] RIP: 0010:bfqq_request_over_limit+0x207/0x400 [ 521.451875] Code: 01 48 8d 0c c8 74 0b 48 8b 82 98 00 00 00 48 8d 0c c8 8b 85 34 ff ff ff 48 89 ca 41 0f af 41 50 48 d1 ea 48 98 48 01 d0 31 d2 <48> f7 f1 41 39 41 48 89 85 34 ff ff ff 0f 8c 7b 01 00 00 49 8b 44 [ 521.452699] RSP: 0018:ffffb1af84eb3948 EFLAGS: 00010046 [ 521.452938] RAX: 000000000000003c RBX: 0000000000000000 RCX: 0000000000000000 [ 521.453262] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffb1af84eb3978 [ 521.453584] RBP: ffffb1af84eb3a30 R08: 0000000000000001 R09: ffff8f88ab8a4ba0 [ 521.453905] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8f88ab8a4b18 [ 521.454224] R13: ffff8f8699093000 R14: 0000000000000001 R15: ffffb1af84eb3970 [ 521.454549] FS: 00005640b6b0b580(0000) GS:ffff8f88b3880000(0000) knlGS:0000000000000000 [ 521.454912] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 521.455170] CR2: 00007ffcbcae4e38 CR3: 00000002e46de001 CR4: 0000000000770ee0 [ 521.455491] PKRU: 55555554 [ 521.455619] Call Trace: [ 521.455736] [ 521.455837] ? bfq_request_merge+0x3a/0xc0 [ 521.456027] ? elv_merge+0x115/0x140 [ 521.456191] bfq_limit_depth+0xc8/0x240 [ 521.456366] __blk_mq_alloc_requests+0x21a/0x2c0 [ 521.456577] blk_mq_submit_bio+0x23c/0x6c0 [ 521.456766] __submit_bio+0xb8/0x140 [ 521.457236] submit_bio_noacct_nocheck+0x212/0x300 [ 521.457748] submit_bio_noacct+0x1a6/0x580 [ 521.458220] submit_bio+0x43/0x80 [ 521.458660] ext4_io_submit+0x23/0x80 [ 521.459116] ext4_do_writepages+0x40a/0xd00 [ 521.459596] ext4_writepages+0x65/0x100 [ 521.460050] do_writepages+0xb7/0x1c0 [ 521.460492] __filemap_fdatawrite_range+0xa6/0x100 [ 521.460979] file_write_and_wait_range+0xbf/0x140 [ 521.461452] ext4_sync_file+0x105/0x340 [ 521.461882] __x64_sys_fsync+0x67/0x100 [ 521.462305] ? syscall_exit_to_user_mode+0x2c/0x1c0 [ 521.462768] do_syscall_64+0x3b/0xc0 [ 521.463165] entry_SYSCALL_64_after_hwframe+0x5a/0xc4 [ 521.463621] RIP: 0033:0x5640b6c56590 [ 521.464006] Code: 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d 71 70 0e 00 00 74 17 b8 4a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c Signed-off-by: Colin Ian King Link: https://lore.kernel.org/r/20230413133009.1605335-1-colin.i.king@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/bfq-iosched.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index d9ed3108c17af..bac977da4eb5b 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -649,6 +649,8 @@ static bool bfqq_request_over_limit(struct bfq_queue *bfqq, int limit) sched_data->service_tree[i].wsum; } } + if (!wsum) + continue; limit = DIV_ROUND_CLOSEST(limit * entity->weight, wsum); if (entity->allocated >= limit) { bfq_log_bfqq(bfqq->bfqd, bfqq, -- 2.39.2