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 76E1EC4332F for ; Wed, 15 Dec 2021 10:05:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236487AbhLOKFO (ORCPT ); Wed, 15 Dec 2021 05:05:14 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:35514 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233723AbhLOKFN (ORCPT ); Wed, 15 Dec 2021 05:05:13 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 5955F1F382; Wed, 15 Dec 2021 10:05:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1639562712; 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=OAAzviErppZGCS8tC7thMjgNf1ikMh2wNe6PPnH5tIU=; b=SW29Usn8ahZEdr7Pb16D31fYyr1zZk8aBIHkD0IBgfvQzyaBgkRoevLfMJtjnzX7iPndpT 8nz8VGl+BHZ7DnHWAevRMiWvK1KzHeQ3nHVQ0znoGVvQe37MyP7VSKKXkpWpIW7yNnMADz cmSOJsFpE0E6dvbI2lf9sIDFv2UtZWo= 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 21AF9A3B83; Wed, 15 Dec 2021 10:05:12 +0000 (UTC) Date: Wed, 15 Dec 2021 11:05:11 +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: <20211214125748.974a400f0b05a633f9b971b7@linux-foundation.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- Michal Hocko SUSE Labs