From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: fs: gpf in simple_setattr Date: Tue, 25 Mar 2014 20:12:48 -0400 Message-ID: <53321B80.4070108@oracle.com> References: <20140305124536.GA32371@quack.suse.cz> <53189BF8.1010308@oracle.com> <531A7CFD.9030603@oracle.com> <20140310104350.GB28797@quack.suse.cz> <531DC89A.9010601@oracle.com> <53304451.7030800@oracle.com> <20140324214851.GB10057@quack.suse.cz> <5330D15E.2000702@oracle.com> <20140325173340.GB17292@quack.suse.cz> <5331C20F.5010109@oracle.com> <20140325211229.GA27422@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Al Viro , linux-fsdevel@vger.kernel.org, LKML , Linus Torvalds To: Jan Kara Return-path: In-Reply-To: <20140325211229.GA27422@quack.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 03/25/2014 05:12 PM, Jan Kara wrote: > On Tue 25-03-14 13:51:11, Sasha Levin wrote: >> On 03/25/2014 01:33 PM, Jan Kara wrote: >>> On Mon 24-03-14 20:44:14, Sasha Levin wrote: >>>> On 03/24/2014 05:48 PM, Jan Kara wrote: >>>>>>> [ 339.948946] ** 4194304 ffff8805ac03ba38 [eventpoll] ffff8806ec051fe0 >>>>>>> [eventpoll] ffffffff84666040 ffff88056c73e7b0 (null) >>>>> OK, great. So finally we have something useful. We know we have problems >>>>> with [eventpoll] dentry. That is actually a special filesystem not mounted >>>>> anywhere - likely you get to that dentry through/proc//fd/. Now >>>>> eventpoll is interesting because it uses single anon inode for all >>>>> eventpoll instances. And that inode should stay in place as long as >>>>> eventpoll filesystem exists. So it's not clear how come that inode is >>>>> freed. The basic check of handling of inode use count didn't find anything >>>>> suspicious. But I can check in more detail and if I fail, we now have a >>>>> pretty narrow area where to look... >>>> >>>> Seems like it's not specific to eventpoll, I saw the same error message with >>>> "eventfd" and "perf_event". >>> Yup, all these use anon_inode_getfile() so it all points to the fact that >>> for some reason we freed anon_inode_inode. But I don't see where the >>> problem is. Can you maybe make 'anon_inode_inode' external to >>> fs/anon_inodes.c and dump stack for all iput() calls to anon_inode_inode? >>> There must be some suckers which don't belong there... >> >> Okay, this is straightforward. It happened right after boot so we're lucky. >> >> I'm also looking into that, but odds you'll spot the issue faster than me. > Can you try whether the following patch fixes the issue for you? Looks like it fixes it, thanks! Thanks, Sasha