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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 4D5FAC433DF for ; Sat, 23 May 2020 15:36:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 214DE2085B for ; Sat, 23 May 2020 15:36:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590248209; bh=iNgQyRFkPo4T6r4KrsKV1rutOYMdI9Jp2l3mBAYVHJg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=1hGyeV+V1/syq9+uBBcSz06Ul39YM/NL9HNdc0OFM+aWZeV1dFNRv+dQc8BcOtFe1 DFXm5uRwBdsGr6Y6Ea/iGXy2t5mstaPkeHHYLbNsCbjo4GcJVbI8qsAckV7J3hM5LT 8jfxwULz++ezIaZjmG7oNyoG8bgL3dnlBlMZgjGs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387946AbgEWPgs (ORCPT ); Sat, 23 May 2020 11:36:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:53118 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728296AbgEWPgr (ORCPT ); Sat, 23 May 2020 11:36:47 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A8236207F7; Sat, 23 May 2020 15:36:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590248206; bh=iNgQyRFkPo4T6r4KrsKV1rutOYMdI9Jp2l3mBAYVHJg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wwNKkkyCnwDejsKRcTgqrGIgCQBGoIrXEHqx7BIrywNUsHMEpY+ZJuaPd6gffHHvc cT5j9htvRVEbi009ZG6N3ATarnmisIY+dRT9x7cQL92+Mnk3103NTAZxLiRdlEz7SB Z4uVXUR+ujVl2Yzvhl3xpUaozEc003DXaHMb2IUc= Date: Sat, 23 May 2020 17:36:43 +0200 From: Greg Kroah-Hartman To: Heikki Krogerus Cc: linux-kernel@vger.kernel.org, Naresh Kamboju , kernel test robot , Brendan Higgins , Randy Dunlap , "Rafael J. Wysocki" Subject: Re: [PATCH] kobject: Make sure the parent does not get released before its children Message-ID: <20200523153643.GA226270@kroah.com> References: <20200513151840.36400-1-heikki.krogerus@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200513151840.36400-1-heikki.krogerus@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 13, 2020 at 06:18:40PM +0300, Heikki Krogerus wrote: > In the function kobject_cleanup(), kobject_del(kobj) is > called before the kobj->release(). That makes it possible to > release the parent of the kobject before the kobject itself. > > To fix that, adding function __kboject_del() that does > everything that kobject_del() does except release the parent > reference. kobject_cleanup() then calls __kobject_del() > instead of kobject_del(), and separately decrements the > reference count of the parent kobject after kobj->release() > has been called. > > Reported-by: Naresh Kamboju > Reported-by: kernel test robot > Fixes: 7589238a8cf3 ("Revert "software node: Simplify software_node_release() function"") > Suggested-by: "Rafael J. Wysocki" > Signed-off-by: Heikki Krogerus > Reviewed-by: Rafael J. Wysocki > Reviewed-by: Brendan Higgins > Tested-by: Brendan Higgins > Acked-by: Randy Dunlap > --- > lib/kobject.c | 30 ++++++++++++++++++++---------- > 1 file changed, 20 insertions(+), 10 deletions(-) Stepping back, now that it turns out this patch causes more problems than it fixes, how is everyone reproducing the original crash here? Is it just the KUNIT_DRIVER_PE_TEST that is causing the issue? In looking at 7589238a8cf3 ("Revert "software node: Simplify software_node_release() function""), the log messages there look correct. sysfs can't create a duplicate file, and so when your test is written to try to create software nodes, you always have to check the return value. If you run the test in parallel, or before another test has had a chance to clean up, the function will fail, correctly. So what real-world thing is this test "failure" trying to show? thanks, greg k-h