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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 25027C433B4 for ; Wed, 14 Apr 2021 12:55:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D9E7B61176 for ; Wed, 14 Apr 2021 12:55:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233647AbhDNM4E (ORCPT ); Wed, 14 Apr 2021 08:56:04 -0400 Received: from mx2.suse.de ([195.135.220.15]:48430 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230303AbhDNM4C (ORCPT ); Wed, 14 Apr 2021 08:56:02 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1618404940; 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=IVVFe9lVz57JQCiJGdKdxrabbFt2psVmdL+WS1cz9u0=; b=S5QL89mvzAHLxuE28gMdDkW7ratvQbt7wf6PzxucjX0wG64l2Z0/KUVICEJtjMD57BdyAq m97dquJ8tv1geZDYSJHmVRrZ/UJig1+1G43MEEbWpxLoRfw+E/z14m9lcHG8BxCJqBf8ra kU7pOhnXLnV9tBzhAAPm2IEBzu14sOc= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 85977AFAB; Wed, 14 Apr 2021 12:55:40 +0000 (UTC) Date: Wed, 14 Apr 2021 14:55:39 +0200 From: Michal Hocko To: Feng Tang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Andrea Arcangeli , David Rientjes , Mel Gorman , Mike Kravetz , Randy Dunlap , Vlastimil Babka , Dave Hansen , Ben Widawsky , Andi Kleen , Dan Williams , Dave Hansen Subject: Re: [PATCH v4 04/13] mm/mempolicy: allow preferred code to take a nodemask Message-ID: References: <1615952410-36895-1-git-send-email-feng.tang@intel.com> <1615952410-36895-5-git-send-email-feng.tang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1615952410-36895-5-git-send-email-feng.tang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 17-03-21 11:40:01, Feng Tang wrote: > From: Dave Hansen > > Create a helper function (mpol_new_preferred_many()) which is usable > both by the old, single-node MPOL_PREFERRED and the new > MPOL_PREFERRED_MANY. > > Enforce the old single-node MPOL_PREFERRED behavior in the "new" > version of mpol_new_preferred() which calls mpol_new_preferred_many(). > > v3: > * fix a stack overflow caused by emty nodemask (Feng) > > Link: https://lore.kernel.org/r/20200630212517.308045-5-ben.widawsky@intel.com > Signed-off-by: Dave Hansen > Signed-off-by: Ben Widawsky > Signed-off-by: Feng Tang > --- > mm/mempolicy.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 1228d8e..6fb2cab 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -203,17 +203,34 @@ static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes) > return 0; > } > > -static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes) > +static int mpol_new_preferred_many(struct mempolicy *pol, > + const nodemask_t *nodes) > { > if (!nodes) > pol->flags |= MPOL_F_LOCAL; /* local allocation */ Now you have confused me. I thought that MPOL_PREFERRED_MANY for NULL nodemask will be disallowed as it is effectively MPOL_PREFERRED aka MPOL_F_LOCAL. Or do I misread the code? > else if (nodes_empty(*nodes)) > return -EINVAL; /* no allowed nodes */ > else > - pol->v.preferred_nodes = nodemask_of_node(first_node(*nodes)); > + pol->v.preferred_nodes = *nodes; > return 0; > } > > +static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes) > +{ > + if (nodes) { > + /* MPOL_PREFERRED can only take a single node: */ > + nodemask_t tmp; > + > + if (nodes_empty(*nodes)) > + return -EINVAL; > + > + tmp = nodemask_of_node(first_node(*nodes)); > + return mpol_new_preferred_many(pol, &tmp); > + } > + > + return mpol_new_preferred_many(pol, NULL); > +} > + > static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes) > { > if (nodes_empty(*nodes)) > -- > 2.7.4 -- Michal Hocko SUSE Labs