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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_MUTT autolearn=unavailable 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 532CDC04AAD for ; Tue, 7 May 2019 17:32:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D28C206A3 for ; Tue, 7 May 2019 17:32:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557250347; bh=5zCQvc4tk1Jvd0RbTsaQiOwTNOiPgVmNjHnmmfGqbes=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=w7FOdnsCjNqI4RnN9On8DtylNcP0CBV0vuiLLgwnLFCb8WoJZ/PaKDIaNDLsRKo6H 3cVFRsJbckWqps2KBbpKDMqPOGfwxpJQnEUpSx5Y4pjw8fibz9XsufPRWjOYzDq8xW PFwoBWv9j1loxMssehlkClPpYDbdIgOgE737IWaQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727428AbfEGRc0 (ORCPT ); Tue, 7 May 2019 13:32:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:55984 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726256AbfEGRc0 (ORCPT ); Tue, 7 May 2019 13:32:26 -0400 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 E641BAEA3; Tue, 7 May 2019 17:32:24 +0000 (UTC) Date: Tue, 7 May 2019 19:32:24 +0200 From: Michal Hocko To: Sasha Levin Cc: Linus Torvalds , Alexander Duyck , LKML , stable , Mikhail Zaslonko , Gerald Schaefer , Mikhail Gavrilov , Dave Hansen , Alexander Duyck , Pasha Tatashin , Martin Schwidefsky , Heiko Carstens , Andrew Morton , Sasha Levin , linux-mm Subject: Re: [PATCH AUTOSEL 4.14 62/95] mm, memory_hotplug: initialize struct pages for the full memory section Message-ID: <20190507173224.GS31017@dhcp22.suse.cz> References: <20190507053826.31622-1-sashal@kernel.org> <20190507053826.31622-62-sashal@kernel.org> <20190507170208.GF1747@sasha-vm> <20190507171806.GG1747@sasha-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190507171806.GG1747@sasha-vm> 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 Tue 07-05-19 13:18:06, Sasha Levin wrote: > On Tue, May 07, 2019 at 10:15:19AM -0700, Linus Torvalds wrote: > > On Tue, May 7, 2019 at 10:02 AM Sasha Levin wrote: > > > > > > I got it wrong then. I'll fix it up and get efad4e475c31 in instead. > > > > Careful. That one had a bug too, and we have 891cb2a72d82 ("mm, > > memory_hotplug: fix off-by-one in is_pageblock_removable"). > > > > All of these were *horribly* and subtly buggy, and might be > > intertwined with other issues. And only trigger on a few specific > > machines where the memory map layout is just right to trigger some > > special case or other, and you have just the right config. > > > > It might be best to verify with Michal Hocko. Michal? > > Michal, is there a testcase I can plug into kselftests to make sure we > got this right (and don't regress)? We care a lot about memory hotplug > working right. As said in other email. The memory hotplug tends to work usually. It takes unexpected memory layouts which trigger corner cases. This makes testing really hard. -- Michal Hocko SUSE Labs