From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 497946B0279 for ; Fri, 9 Jun 2017 02:49:01 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id v104so7138277wrb.6 for ; Thu, 08 Jun 2017 23:49:01 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id n2si717247wmd.2.2017.06.08.23.48.59 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 08 Jun 2017 23:48:59 -0700 (PDT) Subject: Re: Sleeping BUG in khugepaged for i586 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: Vlastimil Babka Message-ID: Date: Fri, 9 Jun 2017 08:48:58 +0200 MIME-Version: 1.0 In-Reply-To: <20170608203046.GB5535@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Matthew Wilcox Cc: David Rientjes , Larry Finger , Andrew Morton , LKML , linux-mm@kvack.org 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?) Vlastimil -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org