From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754123Ab1GVMNF (ORCPT ); Fri, 22 Jul 2011 08:13:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:61073 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753779Ab1GVMNE (ORCPT ); Fri, 22 Jul 2011 08:13:04 -0400 Date: Fri, 22 Jul 2011 08:13:02 -0400 From: Don Zickus To: Huang Ying Cc: "Luck, Tony" , LKML Subject: Re: [PATCH] pstore: change mutex locking to spin_locks Message-ID: <20110722121302.GB9732@redhat.com> References: <1311195386-22743-1-git-send-email-dzickus@redhat.com> <4E277584.1060200@intel.com> <20110721122731.GV3765@redhat.com> <987664A83D2D224EAE907B061CE93D5301E9EC9DC6@orsmsx505.amr.corp.intel.com> <4E28C552.8060803@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E28C552.8060803@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 22, 2011 at 08:33:22AM +0800, Huang Ying wrote: > On 07/22/2011 01:57 AM, Luck, Tony wrote: > >>> Is it safe to call pstore_mkfile with IRQ disabled? > >>> > >>> pstore_mkfile -> d_alloc_name -> d_alloc -> kmem_cache_alloc(, GFP_KERNEL). > >> > >> Don't know. But would that mean we would have to put the pstore_mkfile > >> on a workqueue then or something similar? > > > > That might be a good idea anyway. In the "oops" case we'd like the file > > to appear in the pstore filesystem if the system stayed healthy despite > > the oops[1]. There isn't any reason why the pstore entry must appear instantly. > > Delaying the creation would avoid running into problems related to the > > oops. > > For oops, it may be better to delay writing into something like > workqueue. But for panic, I think we should write the record to backend > (such as ERST) as soon as possible. So maybe it is better to write to > backend as soon as possible and delay writing to pstore filesystem. In the panic case do we care if the pstore fs is mounted (which leads us to run pstore_mkfile)? Actually it seems like most of the entry points into pstore_dumper would not require the fs to create a new file. I think the exception is an oops. Cheers, Don