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=-8.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 BDBD8C43441 for ; Fri, 23 Nov 2018 06:28:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7ED4A20820 for ; Fri, 23 Nov 2018 06:28:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="oc6sn6R2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7ED4A20820 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502086AbeKWRLB (ORCPT ); Fri, 23 Nov 2018 12:11:01 -0500 Received: from mail-pf1-f194.google.com ([209.85.210.194]:34268 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729253AbeKWRLB (ORCPT ); Fri, 23 Nov 2018 12:11:01 -0500 Received: by mail-pf1-f194.google.com with SMTP id h3so2906070pfg.1; Thu, 22 Nov 2018 22:28:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ErDqdjEsmLSbUpdX6oGb3pbSY6xEibcOQetQLQGdD78=; b=oc6sn6R2WOP5kuK129ydTGk7VaczqCIINYeevmJEWgw4OmhG+rsbRfuU+pbhrSN2+v 72rEk8SbTv+zWtPyVFvf7coYd/eYQk/cULHN/j2S3K45SFZneqP4CogWa8R04taVjoD5 3q7+6SecPgbcKgtkCTQ7b3gvXAjy72XCrJIzEK79132vNPyLkGi/kyosTtyNsnCiuPXt ZYGYfDljj1BNXE7sq0jdkx6gjqnZN5b+ixKQARvh/TktBZl0gXZ0x6l9y8Kq1Ce9cFG0 sSwKPpNcMtjkeupxTyV6HcgvJVwwcsYagh8h6xGI2Cbg3EbpFzbYYC/TF09RaOtz/1WO SItA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=ErDqdjEsmLSbUpdX6oGb3pbSY6xEibcOQetQLQGdD78=; b=IqI9boF+fZgIK+xcky0+x8yYFEdVl5xzj5Pl0kfhHngj2egbrOd5sL7FUEA3xnUopC bn3kXi0GkRWnh6Mu/T+A4giPRgfvmlnkGfVTJRZerry55o/uJlXkRMyd7OH7jlPL8Yhe 9Nfpu4OXFhT1FqJk6tqTVPQHlxMZ17hbqysBQrVJEXn4M1e91T2qeukG5Ao4GcfvAeNj ZZgw25OhSxKwu15IT1r5kIml2sBWFMMc2MhVp/MB3tjltZJi7Dg18vnhNOY9e3xqN/sK 59+d5rf8+8samX3KQHpScq6FQNgTI4yaMYoUOVzOvqow6bOgeJFny9MpKWxelllwDdHj EkIg== X-Gm-Message-State: AGRZ1gLTj8doPdVo1tHkDLNWpW26ArtnIzpg05ojxxfUb3PEsgUEF3yv bTDyIhqiHEfRzLNPUGgY6uhegwtRJ/Q= X-Google-Smtp-Source: AJdET5eaanl5jJLsIhXsLHRy0pXGjSSWmVdopvRt2QjZQFPE5BI80DdV5Cqnvy9FXIgv6YhIfUBgPw== X-Received: by 2002:aa7:8497:: with SMTP id u23mr14561578pfn.220.1542954490432; Thu, 22 Nov 2018 22:28:10 -0800 (PST) Received: from bbox-2.seo.corp.google.com ([2401:fa00:d:0:98f1:8b3d:1f37:3e8]) by smtp.gmail.com with ESMTPSA id m67sm468875pfb.25.2018.11.22.22.28.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 22 Nov 2018 22:28:09 -0800 (PST) From: Minchan Kim To: stable@vger.kernel.org Cc: Andrew Morton , hare@suse.com, LKML , sashal@kernel.org, Minchan Kim , Sergey Senozhatsky , Howard Chen Subject: [PATCH for 4.9] zram: close udev startup race condition as default groups Date: Fri, 23 Nov 2018 15:28:02 +0900 Message-Id: <20181123062802.197704-1-minchan@kernel.org> X-Mailer: git-send-email 2.20.0.rc0.387.gc7a69e6b6c-goog In-Reply-To: <20181115174504.GJ95254@sasha-vm> References: <20181115174504.GJ95254@sasha-vm> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit fef912bf860e upstream. commit 98af4d4df889 upstream. I got a report from Howard Chen that he saw zram and sysfs race(ie, zram block device file is created but sysfs for it isn't yet) when he tried to create new zram devices via hotadd knob. v4.20 kernel fixes it by [1, 2] but it's too large size to merge into -stable so this patch fixes the problem by registering defualt group by Greg KH's approach[3]. This patch should be applied to every stable tree [3.16+] currently existing from kernel.org because the problem was introduced at 2.6.37 by [4]. [1] fef912bf860e, block: genhd: add 'groups' argument to device_add_disk [2] 98af4d4df889, zram: register default groups with device_add_disk() [3] http://kroah.com/log/blog/2013/06/26/how-to-create-a-sysfs-file-correctly/ [4] 33863c21e69e9, Staging: zram: Replace ioctls with sysfs interface Cc: Sergey Senozhatsky Cc: Hannes Reinecke Tested-by: Howard Chen Signed-off-by: Minchan Kim --- drivers/block/zram/zram_drv.c | 26 ++++++-------------------- 1 file changed, 6 insertions(+), 20 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index b7c0b69a02f5..d64a53d3270a 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1223,6 +1223,11 @@ static struct attribute_group zram_disk_attr_group = { .attrs = zram_disk_attrs, }; +static const struct attribute_group *zram_disk_attr_groups[] = { + &zram_disk_attr_group, + NULL, +}; + /* * Allocate and initialize new zram device. the function returns * '>= 0' device_id upon success, and negative value otherwise. @@ -1303,24 +1308,15 @@ static int zram_add(void) zram->disk->queue->limits.discard_zeroes_data = 0; queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue); + disk_to_dev(zram->disk)->groups = zram_disk_attr_groups; add_disk(zram->disk); - ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj, - &zram_disk_attr_group); - if (ret < 0) { - pr_err("Error creating sysfs group for device %d\n", - device_id); - goto out_free_disk; - } strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor)); zram->meta = NULL; pr_info("Added device: %s\n", zram->disk->disk_name); return device_id; -out_free_disk: - del_gendisk(zram->disk); - put_disk(zram->disk); out_free_queue: blk_cleanup_queue(queue); out_free_idr: @@ -1348,16 +1344,6 @@ static int zram_remove(struct zram *zram) zram->claim = true; mutex_unlock(&bdev->bd_mutex); - /* - * Remove sysfs first, so no one will perform a disksize - * store while we destroy the devices. This also helps during - * hot_remove -- zram_reset_device() is the last holder of - * ->init_lock, no later/concurrent disksize_store() or any - * other sysfs handlers are possible. - */ - sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, - &zram_disk_attr_group); - /* Make sure all the pending I/O are finished */ fsync_bdev(bdev); zram_reset_device(zram); -- 2.20.0.rc0.387.gc7a69e6b6c-goog