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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 7FE9BC55189 for ; Wed, 22 Apr 2020 09:08:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D1D720767 for ; Wed, 22 Apr 2020 09:08:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726606AbgDVJIf (ORCPT ); Wed, 22 Apr 2020 05:08:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:58536 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725924AbgDVJIf (ORCPT ); Wed, 22 Apr 2020 05:08:35 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id C022DAE47; Wed, 22 Apr 2020 09:08:32 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 00CEF1E125C; Wed, 22 Apr 2020 11:08:32 +0200 (CEST) Date: Wed, 22 Apr 2020 11:08:32 +0200 From: Jan Kara To: Christoph Hellwig Cc: axboe@kernel.dk, yuyufen@huawei.com, tj@kernel.org, jack@suse.cz, bvanassche@acm.org, tytso@mit.edu, hdegoede@redhat.com, gregkh@linuxfoundation.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/9] bdi: add a ->dev_name field to struct backing_dev_info Message-ID: <20200422090832.GE8775@quack2.suse.cz> References: <20200422073851.303714-1-hch@lst.de> <20200422073851.303714-5-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200422073851.303714-5-hch@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 22-04-20 09:38:46, Christoph Hellwig wrote: > Cache a copy of the name for the life time of the backing_dev_info > structure so that we can reference it even after unregistering. > > Fixes: 68f23b89067f ("memcg: fix a crash in wb_workfn when a device disappears") > Reported-by: Yufen Yu > Signed-off-by: Christoph Hellwig Looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > include/linux/backing-dev-defs.h | 1 + > mm/backing-dev.c | 5 +++-- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h > index 4fc87dee005a..2849bdbb3acb 100644 > --- a/include/linux/backing-dev-defs.h > +++ b/include/linux/backing-dev-defs.h > @@ -220,6 +220,7 @@ struct backing_dev_info { > wait_queue_head_t wb_waitq; > > struct device *dev; > + char dev_name[64]; > struct device *owner; > > struct timer_list laptop_mode_wb_timer; > diff --git a/mm/backing-dev.c b/mm/backing-dev.c > index c2c44c89ee5d..efc5b83acd2d 100644 > --- a/mm/backing-dev.c > +++ b/mm/backing-dev.c > @@ -938,7 +938,8 @@ int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args) > if (bdi->dev) /* The driver needs to use separate queues per device */ > return 0; > > - dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args); > + vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args); > + dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name); > if (IS_ERR(dev)) > return PTR_ERR(dev); > > @@ -1047,7 +1048,7 @@ const char *bdi_dev_name(struct backing_dev_info *bdi) > { > if (!bdi || !bdi->dev) > return bdi_unknown_name; > - return dev_name(bdi->dev); > + return bdi->dev_name; > } > EXPORT_SYMBOL_GPL(bdi_dev_name); > > -- > 2.26.1 > -- Jan Kara SUSE Labs, CR