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 F1DB1C33CAC for ; Mon, 3 Feb 2020 12:26:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC75020658 for ; Mon, 3 Feb 2020 12:26:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MWWeKH5B" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728132AbgBCM0T (ORCPT ); Mon, 3 Feb 2020 07:26:19 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:23454 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728129AbgBCM0T (ORCPT ); Mon, 3 Feb 2020 07:26:19 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580732778; 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=1G3DiOYC0S4Ba+SCWCudiO7SLYfZsEB+L93ae7aN88g=; b=MWWeKH5BEDhzlifBHskqs7MNTqdhrdsducnkx6yPlyjFSgD6HVzI3X3zzm0cVZUdsuykuU ZqlMQPGrX2Zntl9pRRaJnBmVJEHCmdQx29FenVcO4ErABnKkYNIW2i1f8CeRuscOFO2DLh NPjddRlB89lQa91QZiVhJG/F68AqMIE= 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-208-hmNPL9KLPyeBBu-orpI8Qg-1; Mon, 03 Feb 2020 07:26:14 -0500 X-MC-Unique: hmNPL9KLPyeBBu-orpI8Qg-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 07DA213E6; Mon, 3 Feb 2020 12:26:13 +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 03DE310841A3; Mon, 3 Feb 2020 12:26:06 +0000 (UTC) Date: Mon, 3 Feb 2020 20:26:02 +0800 From: Ming Lei To: Zhiqiang Liu Cc: Jens Axboe , linux-block@vger.kernel.org, "linux-kernel@vger.kernel.org" , Mingfangsen , Guiyao , Louhongxiang Subject: Re: [PATCH V4] brd: check and limit max_part par Message-ID: <20200203122005.GB31450@ming.t460p> References: <76ad8074-c2ba-4bb3-3e8b-3a4925999964@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <76ad8074-c2ba-4bb3-3e8b-3a4925999964@huawei.com> 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 21, 2020 at 12:04:41PM +0800, Zhiqiang Liu wrote: > > In brd_init func, rd_nr num of brd_device are firstly allocated > and add in brd_devices, then brd_devices are traversed to add each > brd_device by calling add_disk func. When allocating brd_device, > the disk->first_minor is set to i * max_part, if rd_nr * max_part > is larger than MINORMASK, two different brd_device may have the same > devt, then only one of them can be successfully added. > when rmmod brd.ko, it will cause oops when calling brd_exit. > > Follow those steps: > # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576 > # rmmod brd > then, the oops will appear. > > Oops log: > [ 726.613722] Call trace: > [ 726.614175] kernfs_find_ns+0x24/0x130 > [ 726.614852] kernfs_find_and_get_ns+0x44/0x68 > [ 726.615749] sysfs_remove_group+0x38/0xb0 > [ 726.616520] blk_trace_remove_sysfs+0x1c/0x28 > [ 726.617320] blk_unregister_queue+0x98/0x100 > [ 726.618105] del_gendisk+0x144/0x2b8 > [ 726.618759] brd_exit+0x68/0x560 [brd] > [ 726.619501] __arm64_sys_delete_module+0x19c/0x2a0 > [ 726.620384] el0_svc_common+0x78/0x130 > [ 726.621057] el0_svc_handler+0x38/0x78 > [ 726.621738] el0_svc+0x8/0xc > [ 726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260) > > Here, we add brd_check_and_reset_par func to check and limit max_part par. > > -- > V3->V4:(suggested by Ming Lei) > - remove useless change > - add one limit of max_part > > V2->V3: (suggested by Ming Lei) > - clear .minors when running out of consecutive minor space in brd_alloc > - remove limit of rd_nr > > V1->V2: add more checks in brd_check_par_valid as suggested by Ming Lei. > > Signed-off-by: Zhiqiang Liu > --- > drivers/block/brd.c | 27 +++++++++++++++++++++++---- > 1 file changed, 23 insertions(+), 4 deletions(-) > > diff --git a/drivers/block/brd.c b/drivers/block/brd.c > index df8103dd40ac..4684f95e3369 100644 > --- a/drivers/block/brd.c > +++ b/drivers/block/brd.c > @@ -389,11 +389,12 @@ static struct brd_device *brd_alloc(int i) > * is harmless) > */ > blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE); > - disk = brd->brd_disk = alloc_disk(max_part); > + disk = brd->brd_disk = alloc_disk(((i * max_part) & ~MINORMASK) ? > + 0 : max_part); > if (!disk) > goto out_free_queue; > disk->major = RAMDISK_MAJOR; > - disk->first_minor = i * max_part; > + disk->first_minor = i * disk->minors; The above change isn't necessary. > disk->fops = &brd_fops; > disk->private_data = brd; > disk->queue = brd->brd_queue; > @@ -468,6 +469,25 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data) > return kobj; > } > > +static inline void brd_check_and_reset_par(void) > +{ > + if (unlikely(!max_part)) > + max_part = 1; > + > + if (max_part > DISK_MAX_PARTS) { > + pr_info("brd: max_part can't be larger than %d, reset max_part = %d.\n", > + DISK_MAX_PARTS, DISK_MAX_PARTS); > + max_part = DISK_MAX_PARTS; > + } > + > + /* > + * make sure 'max_part' can be divided exactly by (1U << MINORBITS), > + * otherwise, it is possiable to get same dev_t when adding partitions. > + */ > + if ((1U << MINORBITS) % max_part != 0) > + max_part = 1UL << fls(max_part); > +} You should move the above change before capping it to DISK_MAX_PARTS since 1UL << fls() may increase 'max_part'. Thanks, Ming