From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754744AbcJFXVq (ORCPT ); Thu, 6 Oct 2016 19:21:46 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:48241 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751448AbcJFXVh (ORCPT ); Thu, 6 Oct 2016 19:21:37 -0400 DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org 7EB2460290 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=pass smtp.mailfrom=okaya@codeaurora.org Subject: Re: [PATCH] Revert "debugfs: ->d_parent is never NULL or negative" To: Al Viro References: <1475789429-11414-1-git-send-email-okaya@codeaurora.org> <20161006213734.GM19539@ZenIV.linux.org.uk> <20161006220050.GN19539@ZenIV.linux.org.uk> <20161006223729.GO19539@ZenIV.linux.org.uk> <20161006224117.GP19539@ZenIV.linux.org.uk> Cc: timur@codeaurora.org, cov@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Greg Kroah-Hartman , linux-kernel@vger.kernel.org, dmaengine From: Sinan Kaya Message-ID: <65156a02-fe6a-611f-907b-85997ee30755@codeaurora.org> Date: Thu, 6 Oct 2016 19:21:33 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20161006224117.GP19539@ZenIV.linux.org.uk> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/6/2016 6:41 PM, Al Viro wrote: > On Thu, Oct 06, 2016 at 11:37:29PM +0100, Al Viro wrote: > >> If you ever get NULL in ->d_parent of struct dentry instance, you are >> practically certain to have a dangling pointer to memory that used to >> contain a struct dentry at some point but got freed and reused since then. > > ... which is what happens in your case, apparently. ->stats is still > pointing to a dentry that had just been freed and its memory reused. > Thanks for explaining the behavior. I posted the change a minute ago and forgot to include you. dmaengine: qcom_hidma: remove useless debugfs file removal I have a very similar problem with sysfs now. It looks like the new kernel is more assertive than the older ones. I'll post the sysfs change in a minute. -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.