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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 213CDC43217 for ; Tue, 19 Oct 2021 16:30:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 06BFD60E76 for ; Tue, 19 Oct 2021 16:30:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232355AbhJSQc4 (ORCPT ); Tue, 19 Oct 2021 12:32:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:59901 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231495AbhJSQcx (ORCPT ); Tue, 19 Oct 2021 12:32:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634661040; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=PiPwD9y8spZoLZVNjvkxF8b9SR5+UePopQh4Nk2pw54=; b=Cjv+//dt79ECXvLOauVmg/weJnfZM5MpnEwptVs2AcDirhvGTbGfTQhrmSHeNtVlHqxxwm wlddBInjxpIIBR/h5VCoU1/WKrm0DmRGWJTXLNB1/KO8i9C2qiiJHvExxXwGlQtJjLNCZo U6Kuw+Iah3kpShujP50sZbVaHO+Nei8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-304-yTQWi08OMOG3Ccr8Ujy_mw-1; Tue, 19 Oct 2021 12:30:36 -0400 X-MC-Unique: yTQWi08OMOG3Ccr8Ujy_mw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 742D280A5C5; Tue, 19 Oct 2021 16:30:33 +0000 (UTC) Received: from T590 (ovpn-8-19.pek2.redhat.com [10.72.8.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AEC47100238C; Tue, 19 Oct 2021 16:29:58 +0000 (UTC) Date: Wed, 20 Oct 2021 00:29:53 +0800 From: Ming Lei To: Luis Chamberlain Cc: Benjamin Herrenschmidt , Paul Mackerras , tj@kernel.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org, minchan@kernel.org, jeyu@kernel.org, shuah@kernel.org, bvanassche@acm.org, dan.j.williams@intel.com, joe@perches.com, tglx@linutronix.de, keescook@chromium.org, rostedt@goodmis.org, linux-spdx@vger.kernel.org, linux-doc@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 11/12] zram: fix crashes with cpu hotplug multistate Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 19, 2021 at 08:28:21AM -0700, Luis Chamberlain wrote: > On Tue, Oct 19, 2021 at 10:34:41AM +0800, Ming Lei wrote: > > Please try the following patch against upstream(linus or next) tree(basically > > fold revised 2 and 3 of V1, and cover two issues: not fail zram_remove in > > module_exit(), race between zram_remove() and disksize_store()), and see if > > everything is fine for you: > > Page fault ... > > [ 18.284256] zram: Removed device: zram0 > [ 18.312974] BUG: unable to handle page fault for address: > ffffad86de903008 > [ 18.313707] #PF: supervisor read access in kernel mode > [ 18.314248] #PF: error_code(0x0000) - not-present page > [ 18.314797] PGD 100000067 P4D 100000067 PUD 10031e067 PMD 136a28067 That is another race between zram_reset_device() and disksize_store(), which is supposed to be covered by ->init_lock, and follows the delta fix against the last patch I posted, and the whole patch can be found in the github link: https://github.com/ming1/linux/commit/fa6045b1371eb301f392ac84adaf3ad53bb16894 diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index d0cae7a42f4d..a14ba3d350ea 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1704,12 +1704,12 @@ static void zram_reset_device(struct zram *zram) set_capacity_and_notify(zram->disk, 0); part_stat_set_all(zram->disk->part0, 0); - up_write(&zram->init_lock); /* I/O operation under all of CPU are done so let's free */ zram_meta_free(zram, disksize); memset(&zram->stats, 0, sizeof(zram->stats)); zcomp_destroy(comp); reset_bdev(zram); + up_write(&zram->init_lock); } static ssize_t disksize_store(struct device *dev, -- Ming