Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8EFBEC433EF for ; Wed, 15 Dec 2021 12:21:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242399AbhLOMVO (ORCPT ); Wed, 15 Dec 2021 07:21:14 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:57922 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242384AbhLOMVI (ORCPT ); Wed, 15 Dec 2021 07:21:08 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 0F3DF212C1; Wed, 15 Dec 2021 12:21:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1639570862; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=sCQuKlEuH5PJS4RgJOInUUe+I9iRj43vidhR7aKJ1wk=; b=AuQ7HusEJBwwsUOHdHqobSrnXD2eF0GLsHke7nrjev1p2Sx5f5rIPJd0oKcASUkGLLMeq7 QplHpL2iC97GHxeUCk1eyTQ17uiILeI1PxYmQpS49xCWa0w5TrUvqW6Z+NeBySPCYEMMx9 hf5/13lOTk5qNcP7EbVAkSBH0SlFFMI= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id D1234A3B81; Wed, 15 Dec 2021 12:21:01 +0000 (UTC) Date: Wed, 15 Dec 2021 13:20:58 +0100 From: Michal Hocko To: linux-kernel@vger.kernel.org Cc: Dennis Zhou , Alexey Makhalov , "cl@linux.com" , "mm-commits@vger.kernel.org" , "osalvador@suse.de" , "stable@vger.kernel.org" , "tj@kernel.org" Subject: Re: + mm-fix-panic-in-__alloc_pages.patch added to -mm tree Message-ID: References: <20211214125748.974a400f0b05a633f9b971b7@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 15-12-21 11:05:12, Michal Hocko wrote: > On Tue 14-12-21 12:57:48, Andrew Morton wrote: > > On Tue, 14 Dec 2021 11:11:54 +0100 Michal Hocko wrote: > > > > > > I need some clarification here. It sounds like memoryless nodes work on > > > > x86, but hotplug + memoryless nodes isn't a supported use case or you're > > > > introducing it as a new use case? > > > > > > > > If this is a new use case, then I'm inclined to say this patch should > > > > NOT go in and a proper fix should be implemented on hotplug's side. I > > > > don't want to be in the business of having/seeing this conversation > > > > reoccur because we just papered over this issue in percpu. > > > > > > The patch still seems to be in the mmotm tree. I have sent a different > > > fix candidate [1] which should be more robust and cover also other potential > > > places. > > > > > > [1] http://lkml.kernel.org/r/20211214100732.26335-1-mhocko@kernel.org > > > > Is cool, I'm paying attention. > > > > We do want something short and simple for backporting to -stable (like > > Alexey's patch) so please bear that in mind while preparing an > > alternative. > > I think we want something that fixes the underlying problem. Please keep > in mind that the pcp allocation is not the only place to hit the issue. > We have more. I do not want we want to handle each and every one > separately. > > I am definitly not going to push for my solution but if there is a > consensus this is the right approach then I do not think we really want > to implement these partial workarounds. Btw. I forgot to add that if we do not agree on the preallocation approach then the approach should be something like http://lkml.kernel.org/r/51c65635-1dae-6ba4-daf9-db9df0ec35d8@redhat.com proposed by David. -- Michal Hocko SUSE Labs