From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Layton Subject: Re: fs: locks: WARNING: CPU: 16 PID: 4296 at fs/locks.c:236 locks_free_lock_context+0x10d/0x240() Date: Fri, 16 Jan 2015 13:53:04 -0500 Message-ID: <20150116135304.0feeaf15@tlielax.poochiereds.net> References: <54B4A909.9060206@oracle.com> <20150113164441.5b210f48@tlielax.poochiereds.net> <54B5A145.6060108@oracle.com> <20150114092705.39bd4881@tlielax.poochiereds.net> <54B6FF69.3080705@oracle.com> <20150115152247.5e660000@tlielax.poochiereds.net> <54B920BB.3010205@oracle.com> <20150116094028.4ffd675f@tlielax.poochiereds.net> <54B95426.5020509@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Jeff Layton , LKML , linux-fsdevel To: Sasha Levin Return-path: Received: from mail-qc0-f174.google.com ([209.85.216.174]:58942 "EHLO mail-qc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751504AbbAPSxI (ORCPT ); Fri, 16 Jan 2015 13:53:08 -0500 Received: by mail-qc0-f174.google.com with SMTP id c9so18395794qcz.5 for ; Fri, 16 Jan 2015 10:53:07 -0800 (PST) In-Reply-To: <54B95426.5020509@oracle.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, 16 Jan 2015 13:10:46 -0500 Sasha Levin wrote: > On 01/16/2015 09:40 AM, Jeff Layton wrote: > > On Fri, 16 Jan 2015 09:31:23 -0500 > > Sasha Levin wrote: > > > >> On 01/15/2015 03:22 PM, Jeff Layton wrote: > >>> Ok, I tried to reproduce it with that and several variations but it > >>> still doesn't seem to do it for me. Can you try the latest linux-next > >>> tree and see if it's still reproducible there? > >> > >> It's still not in in today's -next, could you send me a patch for testing > >> instead? > >> > > > > Seems to be there for me: > > > > ----------------------[snip]----------------------- > > /* > > * This function is called on the last close of an open file. > > */ > > void locks_remove_file(struct file *filp) > > { > > /* ensure that we see any assignment of i_flctx */ > > smp_rmb(); > > > > /* remove any OFD locks */ > > locks_remove_posix(filp, filp); > > ----------------------[snip]----------------------- > > > > That's actually the right place to put the barrier, I think. We just > > need to ensure that this function sees any assignment to i_flctx that > > occurred before this point. By the time we're here, we shouldn't be > > getting any new locks that matter to this close since the fcheck call > > should fail on any new requests. > > > > If that works, then I'll probably make some other changes to the set > > and re-post it next week. > > > > Many thanks for helping me test this! > > You're right, I somehow missed that. > > But it doesn't fix the issue, I still see it happening, but it seems > to be less frequent(?). > Ok, that was my worry (and one of the reasons I really would like to find some way to reproduce this on my own). I think what I'll do at this point is pull the patchset from linux-next until I can consult with someone who understands this sort of cache-coherency problem better than I do. Once I get it resolved, I'll push it back to my linux-next branch and let you know and we can give it another go. Thanks for the testing so far! -- Jeff Layton