Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760235AbZCMX36 (ORCPT ); Fri, 13 Mar 2009 19:29:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751998AbZCMX3u (ORCPT ); Fri, 13 Mar 2009 19:29:50 -0400 Received: from mail-out2.uio.no ([129.240.10.58]:41663 "EHLO mail-out2.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751223AbZCMX3t (ORCPT ); Fri, 13 Mar 2009 19:29:49 -0400 Subject: Re: [PATCH] fs: fput() can be called from interrupt context From: Trond Myklebust To: Davide Libenzi Cc: Andrew Morton , Eric Dumazet , Jeff Moyer , Avi Kivity , linux-aio , zach.brown@oracle.com, Benjamin LaHaise , Linux Kernel Mailing List , Christoph Lameter In-Reply-To: References: <49B54143.1010607@redhat.com> <49B57CB0.5020300@cosmosbay.com> <49B875F7.3030305@cosmosbay.com> <49B87CFE.4000701@cosmosbay.com> <49B89B22.7080303@cosmosbay.com> <20090311224712.fb8db075.akpm@linux-foundation.org> <49B8A75E.6040409@cosmosbay.com> <20090311233903.f036027a.akpm@linux-foundation.org> Content-Type: text/plain Date: Fri, 13 Mar 2009 19:28:22 -0400 Message-Id: <1236986902.7265.73.camel@heimdal.trondhjem.org> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 Content-Transfer-Encoding: 7bit X-UiO-Spam-info: not spam, SpamAssassin (score=-5.0, required=5.0, autolearn=disabled, UIO_MAIL_IS_INTERNAL=-5, uiobl=NO, uiouri=NO) X-UiO-Scanned: EDC3698AD7EF7EA5914EE7917B7064C79D499098 X-UiO-SPAM-Test: remote_host: 71.227.91.12 spam_score: -49 maxlevel 200 minaction 2 bait 0 mail/h: 1 total 53 max/h 3 blacklist 0 greylist 0 ratelimit 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1583 Lines: 35 On Thu, 2009-03-12 at 06:39 -0700, Davide Libenzi wrote: > On Wed, 11 Mar 2009, Andrew Morton wrote: > > > > Take the time to check how fs/aio.c handle the fput(req->ki_filp) case > > > (or read my 2nd patch, it should spot the thing) > > > > Well yes, a kludge like that seems a bit safer. > > > > It's somewhat encouraging that we're apparently already doing fput() > > from within keventd (although how frequently?). There might be > > problems with file locking, security code, etc from doing fput() from > > an unexpected thread. And then there are all the usual weird problem > > with using the keventd queues which take a long time to get discovered. > > Would it be a huge problem, performance-wise, to stop making ->f_count > tricks in __aio_put_req, and always offload to fput_work the task of > releasing the requests? > If that's a huge problem, IMO the lower impact fix would be to use > aio_fput_routine to loop into a second list, releasing the eventual > eventfd file*. There's no need, IMO, to turn the whole fput() into > IRQ-callable just for this case, when we can contain it into the > particular KAIO+eventfd usage. > Do you really want to see eventd doing umounts and remote flock() calls? This really needs to be run in a thread that can cope with __long__ waits, unavailable servers, etc... Trond -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/