From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3713C43441 for ; Fri, 23 Nov 2018 11:12:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6256C20820 for ; Fri, 23 Nov 2018 11:12:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6256C20820 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2394230AbeKWV4a (ORCPT ); Fri, 23 Nov 2018 16:56:30 -0500 Received: from mx2.suse.de ([195.135.220.15]:52606 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387941AbeKWV4a (ORCPT ); Fri, 23 Nov 2018 16:56:30 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id BFC47AF11; Fri, 23 Nov 2018 11:12:38 +0000 (UTC) Date: Fri, 23 Nov 2018 12:12:37 +0100 From: Michal Hocko To: Daniel Vetter Cc: LKML , Linux MM , Intel Graphics Development , DRI Development , Andrew Morton , David Rientjes , Christian =?iso-8859-1?Q?K=F6nig?= , =?iso-8859-1?B?Suly9G1l?= Glisse , Daniel Vetter Subject: Re: [PATCH 2/3] mm, notifier: Catch sleeping/blocking for !blockable Message-ID: <20181123111237.GE8625@dhcp22.suse.cz> References: <20181122165106.18238-1-daniel.vetter@ffwll.ch> <20181122165106.18238-3-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20181122165106.18238-3-daniel.vetter@ffwll.ch> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 22-11-18 17:51:05, Daniel Vetter wrote: > We need to make sure implementations don't cheat and don't have a > possible schedule/blocking point deeply burried where review can't > catch it. > > I'm not sure whether this is the best way to make sure all the > might_sleep() callsites trigger, and it's a bit ugly in the code flow. > But it gets the job done. Yeah, it is quite ugly. Especially because it makes DEBUG config bahavior much different. So is this really worth it? Has this already discovered any existing bug? > Cc: Andrew Morton > Cc: Michal Hocko > Cc: David Rientjes > Cc: "Christian König" > Cc: Daniel Vetter > Cc: "Jérôme Glisse" > Cc: linux-mm@kvack.org > Signed-off-by: Daniel Vetter > --- > mm/mmu_notifier.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index 59e102589a25..4d282cfb296e 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -185,7 +185,13 @@ int __mmu_notifier_invalidate_range_start(struct mm_struct *mm, > id = srcu_read_lock(&srcu); > hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) { > if (mn->ops->invalidate_range_start) { > - int _ret = mn->ops->invalidate_range_start(mn, mm, start, end, blockable); > + int _ret; > + > + if (IS_ENABLED(CONFIG_DEBUG_ATOMIC_SLEEP) && !blockable) > + preempt_disable(); > + _ret = mn->ops->invalidate_range_start(mn, mm, start, end, blockable); > + if (IS_ENABLED(CONFIG_DEBUG_ATOMIC_SLEEP) && !blockable) > + preempt_enable(); > if (_ret) { > pr_info("%pS callback failed with %d in %sblockable context.\n", > mn->ops->invalidate_range_start, _ret, > -- > 2.19.1 > -- Michal Hocko SUSE Labs