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=-9.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 C249DC2BA2B for ; Thu, 16 Apr 2020 07:17:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9955C206D5 for ; Thu, 16 Apr 2020 07:17:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="VzBHyF2i" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2439027AbgDPHRE (ORCPT ); Thu, 16 Apr 2020 03:17:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S2438101AbgDPHPi (ORCPT ); Thu, 16 Apr 2020 03:15:38 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD1D9C0610D5; Thu, 16 Apr 2020 00:15:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=b7FtVufzfrDqdrI7Jtm65uDbDTAbyPNK71CKczufNq4=; b=VzBHyF2i45emK+0pREh3JHgnux 92tmEhshbeZ3WWV6JXXTAXpZ96YCgM3wTaQNWcOwpOYloHGfhuMZFUNOYWJW0iceUP47oI7f+YsTa 2W5m1eX4zf7tXpCo4tNoxsTAbJn5R3Ni3PEF3WtkmxY2Re+6F31ldzmvyFSCOIx6NmbfAbd3t8x1n V/QkrkQWcGIRgZ91DovFPzeYh61xpleJZyopSTm0XMlH7haCXCEmR1JsWMILPkA88VvxoF5/ff9XM C9GADxCYpLZsVN41pD69JvnkzFjdaBFT10A/dI9KfIFtH71qaNrJtUl74ovQvfch6sEoszJHqn1L0 0vjjcSdA==; Received: from [2001:4bb8:184:4aa1:c70:4a89:bc61:2] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jOykE-0003IA-Fn; Thu, 16 Apr 2020 07:15:31 +0000 From: Christoph Hellwig To: axboe@kernel.dk Cc: yuyufen@huawei.com, tj@kernel.org, jack@suse.cz, bvanassche@acm.org, tytso@mit.edu, gregkh@linuxfoundation.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/8] bdi: add a ->dev_name field to struct backing_dev_info Date: Thu, 16 Apr 2020 09:15:14 +0200 Message-Id: <20200416071519.807660-4-hch@lst.de> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200416071519.807660-1-hch@lst.de> References: <20200416071519.807660-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- include/linux/backing-dev-defs.h | 1 + mm/backing-dev.c | 13 ++++++++++--- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index 4fc87dee005a..249590bcccf7 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; + const char *dev_name; struct device *owner; struct timer_list laptop_mode_wb_timer; diff --git a/mm/backing-dev.c b/mm/backing-dev.c index c2c44c89ee5d..4f6c05df72f9 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -938,9 +938,15 @@ 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); - if (IS_ERR(dev)) + bdi->dev_name = kvasprintf(GFP_KERNEL, fmt, args); + if (!bdi->dev_name) + return -ENOMEM; + + dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name); + if (IS_ERR(dev)) { + kfree(bdi->dev_name); return PTR_ERR(dev); + } cgwb_bdi_register(bdi); bdi->dev = dev; @@ -1034,6 +1040,7 @@ static void release_bdi(struct kref *ref) WARN_ON_ONCE(bdi->dev); wb_exit(&bdi->wb); cgwb_bdi_exit(bdi); + kfree(bdi->dev_name); kfree(bdi); } @@ -1047,7 +1054,7 @@ 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); -- 2.25.1