From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: Re: [autofs] [RFC PATCH]autofs4: hang and proposed fix Date: Tue, 6 Dec 2005 16:20:29 -0500 Message-ID: <17302.157.540958.723305@segfault.boston.redhat.com> References: <438E1A05.7000308@us.ibm.com> <438F251B.7060602@us.ibm.com> <43906968.6080508@us.ibm.com> <1133547148.8976.25.camel@lade.trondhjem.org> <20051204125612.GA28229@infradead.org> <20051204125740.GB28229@infradead.org> <20051204171729.GA31111@infradead.org> Reply-To: jmoyer@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: Ian Kent , Trond Myklebust , Will Taber , Ram Pai , autofs mailing list , linux-fsdevel Return-path: Received: from mx1.redhat.com ([66.187.233.31]:34769 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1030249AbVLFVVD (ORCPT ); Tue, 6 Dec 2005 16:21:03 -0500 To: Christoph Hellwig In-Reply-To: <20051204171729.GA31111@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org ==> Regarding Re: [autofs] [RFC PATCH]autofs4: hang and proposed fix; Christoph Hellwig adds: hch> On Sun, Dec 04, 2005 at 10:58:03PM +0800, Ian Kent wrote: >> > never called by the VFS. autofs (v4 at least) doesn't use it so now >> always > get a nameidata. In fact if you look in -mm there's a patch >> from me that > makes use of that fact. >> > >> >> But Will is calling it in a something like a stacking context and autofs >> fails to handle it. Hence this discussion. hch> No, for current TOT that can't happen. It could happen for older hch> kernels but nothing is doing it in the tree anymore and if anything hch> outside is doing it it's fundamentally broken. This is a bit unclear to me. What do you mean when you refer to "it" and "that" above? Oh, and TOT is a TLA I haven't run across before. We know that there is at least one out of tree module that calls lookup_one_len, and ends up in the autofs4 revalidate code without the valid nameidata structure. In this case, with your patch, wouldn't we blindly dereference the structure and cause an oops? If so, who is at fault? Thanks, Jeff