From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755177AbZENSAk (ORCPT ); Thu, 14 May 2009 14:00:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753229AbZENSAH (ORCPT ); Thu, 14 May 2009 14:00:07 -0400 Received: from brick.kernel.dk ([93.163.65.50]:40079 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752789AbZENSAF (ORCPT ); Thu, 14 May 2009 14:00:05 -0400 Date: Thu, 14 May 2009 20:00:03 +0200 From: Jens Axboe To: Miklos Szeredi Cc: akpm@linux-foundation.org, max@duempel.org, torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch 2/3] splice: implement default splice_read method Message-ID: <20090514180003.GU4140@kernel.dk> References: <20090507133734.450612199@szeredi.hu> <20090507133748.161689790@szeredi.hu> <20090512223500.d7ef4648.akpm@linux-foundation.org> <20090513063707.GC4140@kernel.dk> <20090514172935.GR4140@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 14 2009, Miklos Szeredi wrote: > On Thu, 14 May 2009, Jens Axboe wrote: > > > > The bigger problem is that the default_file_splice_write() > > > implementation in the other patch does the same (it calls > > > buf->ops->map() on all buffers). > > > > Yep that's even worse, as that should go BUG() pretty much immediately > > when the KM_USER0 slot is reused! > > No, ->map() calls plain kmap() if "atomic" argument is zero. > Nevertheless the deadlock due to multiple kmaps is still possible. It's buggy either way, didn't check whether you used atomic maps or not. > > > Hmm. Simple solution would be to do a write() for each buffer. But > > > this only affects HIGHMEM kernels, so it's a bit pointless to do that > > > on all archs. Sigh... > > > > It is unfortunate, we are going to be stuck with that for some time > > still... > > I'm going to be offline till next monday, I'll post a fix after that. Until monday, or the monday after? I'm tempted to revert the readv/writev part until this is settled, we cannot ship it as-is. -- Jens Axboe