From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757310Ab3J1RYF (ORCPT ); Mon, 28 Oct 2013 13:24:05 -0400 Received: from mail-ie0-f174.google.com ([209.85.223.174]:33791 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756983Ab3J1RYC (ORCPT ); Mon, 28 Oct 2013 13:24:02 -0400 MIME-Version: 1.0 In-Reply-To: <20131027212407.GA17439@kroah.com> References: <525BD08C.2080101@t-online.de> <20131027212407.GA17439@kroah.com> From: Bjorn Helgaas Date: Mon, 28 Oct 2013 11:23:41 -0600 Message-ID: Subject: Re: [BUG 3.12.rc4] Oops: unable to handle kernel paging request during shutdown To: Greg Kroah-Hartman Cc: Linus Torvalds , Thomas Gleixner , Yinghai Lu , Knut Petersen , Ingo Molnar , Paul McKenney , =?ISO-8859-1?Q?Fr=E9d=E9ric_Weisbecker?= , linux-kernel , "linux-pci@vger.kernel.org" , Veaceslav Falico Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [+cc Veaceslav] On Sun, Oct 27, 2013 at 3:24 PM, Greg Kroah-Hartman wrote: > On Sun, Oct 27, 2013 at 09:13:29PM +0000, Linus Torvalds wrote: >> .. and one more case of freeing a delayed work object (likely a kobject again): >> >> This time it looks like it's in the PCI layer, freeing the msi irq information. >> >> It looks like that code simply does >> >> kobject_del(&entry->kobj); >> kobject_put(&entry->kobj); >> list_del(&entry->list); >> kfree(entry); >> >> and the problem is that the "entry->kobj" may have *other* references >> to it, thanks to people accessing it through /sys, so despite doing a >> kojbect_del/kobject_put(), it's not at all ok to then do a "kfree()" >> on it. The embedded kobj might still be in use. >> >> Afaik, that code should do the kfree() on the kobject in the _release_ >> method, not synchronously like that. >> >> We already have a msi_kobj_release(), I'm wondering why that doesn't >> do the kfree(). >> >> Bjorn? Yinghai? Greg, comments about that msi kobj usage? > > Ick, it really should be doing a kfree() in the release only. Bjorn has > had a bunch of changes in this area recently, perhaps they are in > linux-next waiting for 3.13, and I've talked to him about getting rid of > all of the kobjects for msi files, as I don't think it's needed at all. IIRC, you said you might take a look at converting this to attributes on the train back home, so I haven't looked into it myself :) > Bjorn, don't you have a fix for this problem already done somewhere? Yep, this is clearly wrong, and Veaceslav has a patch that moves the kfree() to the release function. I've been waiting for a consolidated repost of all his MSI-related fixes, but maybe he's been waiting for *me*. Bjorn