Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751727AbdFIO2h (ORCPT ); Fri, 9 Jun 2017 10:28:37 -0400 Received: from mail-oi0-f68.google.com ([209.85.218.68]:36369 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751538AbdFIO2f (ORCPT ); Fri, 9 Jun 2017 10:28:35 -0400 Subject: Re: Sleeping BUG in khugepaged for i586 To: Vlastimil Babka , Michal Hocko , Matthew Wilcox Cc: David Rientjes , Andrew Morton , LKML , linux-mm@kvack.org References: <968ae9a9-5345-18ca-c7ce-d9beaf9f43b6@lwfinger.net> <20170605144401.5a7e62887b476f0732560fa0@linux-foundation.org> <1e883924-9766-4d2a-936c-7a49b337f9e2@lwfinger.net> <9ab81c3c-e064-66d2-6e82-fc9bac125f56@suse.cz> <20170608144831.GA19903@dhcp22.suse.cz> <20170608170557.GA8118@bombadil.infradead.org> <20170608201822.GA5535@dhcp22.suse.cz> <20170608203046.GB5535@dhcp22.suse.cz> From: Larry Finger Message-ID: <20924f94-1959-338c-b585-0c69a895aa39@lwfinger.net> Date: Fri, 9 Jun 2017 09:28:33 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 966 Lines: 20 On 06/09/2017 01:48 AM, Vlastimil Babka wrote: > On 06/08/2017 10:30 PM, Michal Hocko wrote: >> But I guess you are primary after syncing the preemptive mode for 64 and >> 32b systems, right? I agree that having a different model is more than >> unfortunate because 32b gets much less testing coverage and so a risk of >> introducing a new bug is just a matter of time. Maybe we should make >> pte_offset_map disable preemption and currently noop pte_unmap to >> preempt_enable. The overhead should be pretty marginal on x86_64 but not >> all arches have per-cpu preempt count. So I am not sure we really want >> to add this to just for the debugging purposes... > > I think adding that overhead for everyone would be unfortunate. It would > be acceptable, if it was done only for the config option that enables > the might_sleep() checks (CONFIG_DEBUG_ATOMIC_SLEEP?) As a "heads up", I will not be available for any testing from June 10 through June 17. Larry