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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36CB0C67871 for ; Thu, 27 Oct 2022 07:11:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233974AbiJ0HK6 (ORCPT ); Thu, 27 Oct 2022 03:10:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233506AbiJ0HKx (ORCPT ); Thu, 27 Oct 2022 03:10:53 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DC93635C2; Thu, 27 Oct 2022 00:10:31 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id B54DA22131; Thu, 27 Oct 2022 07:10:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1666854629; 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=QCPTXBtSuvGJ41I50Ajt8waPylXnOrME9Qo8riEvBNs=; b=XV2ShTSF4yMp1EabKplEgz+GtFZweYHSKQhHbBajveqkzRHYsGy8eq+D0MRC6mXFe20ADN TtCHe5UXI87D9NRXQWAii9m1kRipuCxXtgYrSAL8Egtf/cHPgQjj5R2D5kZwrQ/tlwGxBk hRiLB37+QpZjrTyXUkMZD7LMu/NYpAg= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 9765F13357; Thu, 27 Oct 2022 07:10:29 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id zaWXGOUuWmOLHQAAMHmgww (envelope-from ); Thu, 27 Oct 2022 07:10:29 +0000 Date: Thu, 27 Oct 2022 09:10:28 +0200 From: Michal Hocko To: "Huang, Ying" Cc: Feng Tang , Aneesh Kumar K V , Andrew Morton , Johannes Weiner , Tejun Heo , Zefan Li , Waiman Long , "linux-mm@kvack.org" , "cgroups@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Hansen, Dave" , "Chen, Tim C" , "Yin, Fengwei" Subject: Re: [PATCH] mm/vmscan: respect cpuset policy during page demotion Message-ID: References: <20221026074343.6517-1-feng.tang@intel.com> <87wn8lkbk5.fsf@yhuang6-desk2.ccr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87wn8lkbk5.fsf@yhuang6-desk2.ccr.corp.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 27-10-22 14:47:22, Huang, Ying wrote: > Michal Hocko writes: [...] > > I can imagine workloads which wouldn't like to get their memory demoted > > for some reason but wouldn't it be more practical to tell that > > explicitly (e.g. via prctl) rather than configuring cpusets/memory > > policies explicitly? > > If my understanding were correct, prctl() configures the process or > thread. Not necessarily. There are properties which are per adddress space like PR_[GS]ET_THP_DISABLE. This could be very similar. > How can we get process/thread configuration at demotion time? As already pointed out in previous emails. You could hook into folio_check_references path, more specifically folio_referenced_one where you have all that you need already - all vmas mapping the page and then it is trivial to get the corresponding vm_mm. If at least one of them has the flag set then the demotion is not allowed (essentially the same model as VM_LOCKED). -- Michal Hocko SUSE Labs