From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:57296 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751133AbdJCVJ4 (ORCPT ); Tue, 3 Oct 2017 17:09:56 -0400 MIME-Version: 1.0 In-Reply-To: References: <20171003185313.1017-1-mcgrof@kernel.org> <20171003185313.1017-6-mcgrof@kernel.org> <20171003201204.GA23521@amd> <20171003202121.GB23521@amd> <20171003205739.GA30569@amd> From: Shuah Khan Date: Tue, 3 Oct 2017 15:09:53 -0600 Message-ID: Subject: Re: [RFC 5/5] pm: remove kernel thread freezing Content-Type: text/plain; charset="UTF-8" Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Jiri Kosina , mchehab@s-opensource.com Cc: Pavel Machek , "Luis R. Rodriguez" , viro@zeniv.linux.org.uk, bart.vanassche@wdc.com, ming.lei@redhat.com, tytso@mit.edu, darrick.wong@oracle.com, rjw@rjwysocki.net, len.brown@intel.com, linux-fsdevel@vger.kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com, todd.e.brandt@linux.intel.com, nborisov@suse.com, jack@suse.cz, martin.petersen@oracle.com, ONeukum@suse.com, oleksandr@natalenko.name, oleg.b.antonyan@gmail.com, Linux PM list , linux-block@vger.kernel.org, linux-xfs@vger.kernel.org, LKML , linux-media@vger.kernel.org, shuahkh@osg.samsung.com On Tue, Oct 3, 2017 at 3:00 PM, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Pavel Machek wrote: > >> > Again, I agree that the (rare) kthreads that are actually "creating" new >> > I/O have to be somehow frozen and require special care. >> >> Agreed. Was any effort made to identify those special kernel threads? > > I don't think there is any other way than just inspecting all the > try_to_freeze() instances in the kernel, and understanding what that > particular kthread is doing. > > I've cleaned up most of the low-hanging fruit already, where the > try_to_freeze() was obviously completely pointless, but a lot more time > needs to be invested into this. > There are about 36 drivers that call try_to_freeze() and half (18 ) of those are media drivers. Maybe it is easier handle sub-system by sub-system basis for a review of which one of these usages could be removed. cc'ing Mauro and linux-media thanks, -- Shuah