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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 75979C83004 for ; Wed, 29 Apr 2020 09:50:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 382FB2137B for ; Wed, 29 Apr 2020 09:50:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="pvRgpyuC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 382FB2137B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D174A8E0006; Wed, 29 Apr 2020 05:50:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CED9F8E0001; Wed, 29 Apr 2020 05:50:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BDC7D8E0006; Wed, 29 Apr 2020 05:50:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0124.hostedemail.com [216.40.44.124]) by kanga.kvack.org (Postfix) with ESMTP id A0BF98E0001 for ; Wed, 29 Apr 2020 05:50:37 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 5D28098A6 for ; Wed, 29 Apr 2020 09:50:37 +0000 (UTC) X-FDA: 76760422914.06.size92_79cec77b06c22 X-HE-Tag: size92_79cec77b06c22 X-Filterd-Recvd-Size: 2842 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Wed, 29 Apr 2020 09:50:36 +0000 (UTC) Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8ABC520775; Wed, 29 Apr 2020 09:50:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588153836; bh=pulymwHUCy+ILUA/eItQyTrcE9Pq+/nb//736se0uVU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pvRgpyuCu/jL6tMLpZQVAitTpFH117anPbvmGsSdTbiAlARdIlYkvVaTYIuq5viUZ zac4jOJIMVsXc8PjaN7NDU9Z6TjOHuuPedW+BNx7K0DCZCJ5UMMcwPgvmuHGk+KxRe btwWd8PTbaYQzqw8QQ38xkiHc7DJTnLS40jtPkxE= Date: Wed, 29 Apr 2020 11:50:34 +0200 From: Greg KH To: Luis Chamberlain Cc: axboe@kernel.dk, viro@zeniv.linux.org.uk, bvanassche@acm.org, rostedt@goodmis.org, mingo@redhat.com, jack@suse.cz, ming.lei@redhat.com, nstange@suse.de, akpm@linux-foundation.org, mhocko@suse.com, yukuai3@huawei.com, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 6/6] loop: be paranoid on exit and prevent new additions / removals Message-ID: <20200429095034.GC2081185@kroah.com> References: <20200429074627.5955-1-mcgrof@kernel.org> <20200429074627.5955-7-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200429074627.5955-7-mcgrof@kernel.org> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 29, 2020 at 07:46:27AM +0000, Luis Chamberlain wrote: > Be pedantic on removal as well and hold the mutex. > This should prevent uses of addition while we exit. > > Signed-off-by: Luis Chamberlain > --- > drivers/block/loop.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index da693e6a834e..6dccba22c9b5 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -2333,6 +2333,8 @@ static void __exit loop_exit(void) > > range = max_loop ? max_loop << part_shift : 1UL << MINORBITS; > > + mutex_lock(&loop_ctl_mutex); > + > idr_for_each(&loop_index_idr, &loop_exit_cb, NULL); > idr_destroy(&loop_index_idr); > > @@ -2340,6 +2342,8 @@ static void __exit loop_exit(void) > unregister_blkdev(LOOP_MAJOR, "loop"); > > misc_deregister(&loop_misc); > + > + mutex_unlock(&loop_ctl_mutex); > } > > module_init(loop_init); What type of issue is this helping with? Can it be triggered today? if so, shouldn't it be backported to stable kernels? thanks, greg k-h