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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 64566C33C8C for ; Tue, 7 Jan 2020 15:23:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B27D222D9 for ; Tue, 7 Jan 2020 15:23:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Qz4Fvb9B" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728335AbgAGPXz (ORCPT ); Tue, 7 Jan 2020 10:23:55 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:23515 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728334AbgAGPXz (ORCPT ); Tue, 7 Jan 2020 10:23:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578410633; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0uNiCTiEHFgNN9K+lpJkW469fllh6SCfCoNUo1eAVpg=; b=Qz4Fvb9BcjnqsbMcKCXvLw55s95WZJ7EGVFOmt2FnXz8Nvfghi4hy3C/B9PzTVQRFPRCH/ TcRdBYpewr/Qx9StuQUI5NMuFscZz94LifeRbH629L93saThC0fsXIJrN4j2K7ePfCMdra +zYPbyKNLi4MQax2I9To+uxZdK//vU4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-230-YZmiAk9SPXu1Dk_Vw51d_w-1; Tue, 07 Jan 2020 10:23:50 -0500 X-MC-Unique: YZmiAk9SPXu1Dk_Vw51d_w-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CF6BA1005514; Tue, 7 Jan 2020 15:23:48 +0000 (UTC) Received: from ming.t460p (ovpn-8-25.pek2.redhat.com [10.72.8.25]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9026E10018FF; Tue, 7 Jan 2020 15:23:43 +0000 (UTC) Date: Tue, 7 Jan 2020 23:23:39 +0800 From: Ming Lei To: Guenter Roeck Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Mason Subject: Re: [PATCH] block: fix splitting segments Message-ID: <20200107152339.GA23622@ming.t460p> References: <20191229023230.28940-1-ming.lei@redhat.com> <20200107124708.GA20285@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200107124708.GA20285@roeck-us.net> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Jan 07, 2020 at 04:47:08AM -0800, Guenter Roeck wrote: > Hi, > > On Sun, Dec 29, 2019 at 10:32:30AM +0800, Ming Lei wrote: > > There are two issues in get_max_segment_size(): > > > > 1) the default segment boudary mask is bypassed, and some devices still > > require segment to not cross the default 4G boundary > > > > 2) the segment start address isn't taken into account when checking > > segment boundary limit > > > > Fixes the two issues. > > > > Fixes: dcebd755926b ("block: use bio_for_each_bvec() to compute multi-page bvec count") > > Signed-off-by: Ming Lei > > This patch, pushed into mainline as "block: fix splitting segments on > boundary masks", results in the following crash when booting 'versatilepb' > in qemu from disk. Bisect log is attached. Detailed log is at > https://kerneltests.org/builders/qemu-arm-master/builds/1410/steps/qemubuildcommand/logs/stdio > > Guenter > > --- > Crash: > > kernel BUG at block/bio.c:1885! > Internal error: Oops - BUG: 0 [#1] ARM Please apply the following debug patch, and post the log. diff --git a/block/blk-merge.c b/block/blk-merge.c index 347782a24a35..c4aa683a1c20 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -217,6 +217,33 @@ static bool bvec_split_segs(const struct request_queue *q, return len > 0 || bv->bv_len > max_len; } +static void blk_dump_bio(struct request_queue *q, struct bio *bio, + unsigned secs) +{ + struct bvec_iter iter; + struct bio_vec bvec; + int i = 0; + unsigned sectors = 0; + + printk("max_sectors %u max_segs %u max_seg_size %u mask %lx\n", + get_max_io_size(q, bio), queue_max_segments(q), + queue_max_segment_size(q), queue_segment_boundary(q)); + printk("%p: %hx/%hx %llu %u, %u\n", + bio, + bio->bi_flags, bio->bi_opf, + (unsigned long long)bio->bi_iter.bi_sector, + bio->bi_iter.bi_size, secs); + bio_for_each_bvec(bvec, bio, iter) { + sectors += bvec.bv_len >> 9; + trace_printk("\t %d: %lu %u %u(%u)\n", i++, + (unsigned long)page_to_pfn(bvec.bv_page), + bvec.bv_offset, + bvec.bv_len, bvec.bv_len >> 12); + } + printk("\t total sectors %u\n", sectors); +} + + /** * blk_bio_segment_split - split a bio in two bios * @q: [in] request queue pointer @@ -273,6 +300,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, return NULL; split: *segs = nsegs; + + if (sectors <= 0 || sectors >= bio_sectors(bio)) + blk_dump_bio(q, bio, sectors); return bio_split(bio, sectors, GFP_NOIO, bs); } Thanks, Ming