From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:59224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725843AbeKTSTi (ORCPT ); Tue, 20 Nov 2018 13:19:38 -0500 Date: Tue, 20 Nov 2018 08:51:50 +0100 From: Greg Kroah-Hartman To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, "jianchao.wang" , Guenter Roeck , stable@vger.kernel.org Subject: Re: [PATCH 4.21 V3] blk-mq: not embed .mq_kobj and ctx->kobj into queue instance Message-ID: <20181120075150.GF15276@kroah.com> References: <20181120014435.3339-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181120014435.3339-1-ming.lei@redhat.com> Sender: stable-owner@vger.kernel.org List-ID: On Tue, Nov 20, 2018 at 09:44:35AM +0800, Ming Lei wrote: > Even though .mq_kobj, ctx->kobj and q->kobj share same lifetime > from block layer's view, actually they don't because userspace may > grab one kobject anytime via sysfs. > > This patch fixes the issue by the following approach: > > 1) introduce 'struct blk_mq_ctxs' for holding .mq_kobj and managing > all ctxs > > 2) free all allocated ctxs and the 'blk_mq_ctxs' instance in release > handler of .mq_kobj > > 3) grab one ref of .mq_kobj before initializing each ctx->kobj, so that > .mq_kobj is always released after all ctxs are freed. > > This patch fixes kernel panic issue during booting when DEBUG_KOBJECT_RELEASE > is enabled. > > Reported-by: Guenter Roeck > Cc: "jianchao.wang" > Cc: Guenter Roeck > Cc: Greg Kroah-Hartman > Cc: stable@vger.kernel.org > Signed-off-by: Ming Lei > --- > V3: > - keep to allocate q->queue_ctx via percpu allocator, so one extra > pointer reference can be saved for getting ctx > V2: > - allocate 'blk_mq_ctx' inside blk_mq_init_allocated_queue() > - allocate q->mq_kobj directly Not tested, but seems sane from a kobject point-of-view: Reviewed-by: Greg Kroah-Hartman