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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 3A92CC63797 for ; Tue, 20 Jul 2021 15:44:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1049961245 for ; Tue, 20 Jul 2021 15:44:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234510AbhGTPA3 (ORCPT ); Tue, 20 Jul 2021 11:00:29 -0400 Received: from mga12.intel.com ([192.55.52.136]:15550 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241911AbhGTO5G (ORCPT ); Tue, 20 Jul 2021 10:57:06 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10050"; a="190846215" X-IronPort-AV: E=Sophos;i="5.84,255,1620716400"; d="scan'208";a="190846215" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jul 2021 08:37:05 -0700 X-IronPort-AV: E=Sophos;i="5.84,255,1620716400"; d="scan'208";a="469799017" Received: from lesliemu-mobl1.amr.corp.intel.com (HELO intel.com) ([10.252.136.56]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jul 2021 08:37:04 -0700 Date: Tue, 20 Jul 2021 08:37:00 -0700 From: Ben Widawsky To: Xiyu Yang Cc: Andrew Morton , Feng Tang , Mike Kravetz , Muchun Song , Yanfei Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, yuanxzhang@fudan.edu.cn, Xin Tan Subject: Re: [PATCH] mm/mempolicy: Convert from atomic_t to refcount_t on mempolicy->refcnt Message-ID: <20210720153700.tqq4d7fronda42ro@intel.com> Mail-Followup-To: Xiyu Yang , Andrew Morton , Feng Tang , Mike Kravetz , Muchun Song , Yanfei Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, yuanxzhang@fudan.edu.cn, Xin Tan References: <1626683671-64407-1-git-send-email-xiyuyang19@fudan.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1626683671-64407-1-git-send-email-xiyuyang19@fudan.edu.cn> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21-07-19 16:34:28, Xiyu Yang wrote: > refcount_t type and corresponding API can protect refcounters from > accidental underflow and overflow and further use-after-free situations. > > Signed-off-by: Xiyu Yang > Signed-off-by: Xin Tan lgtm Acked-by: Ben Widawsky > --- > include/linux/mempolicy.h | 5 +++-- > mm/mempolicy.c | 8 ++++---- > 2 files changed, 7 insertions(+), 6 deletions(-) > > diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h > index 0aaf91b496e2..faec94994eb7 100644 > --- a/include/linux/mempolicy.h > +++ b/include/linux/mempolicy.h > @@ -6,6 +6,7 @@ > #ifndef _LINUX_MEMPOLICY_H > #define _LINUX_MEMPOLICY_H 1 > > +#include > #include > #include > #include > @@ -43,7 +44,7 @@ struct mm_struct; > * to 1, representing the caller of mpol_dup(). > */ > struct mempolicy { > - atomic_t refcnt; > + refcount_t refcnt; > unsigned short mode; /* See MPOL_* above */ > unsigned short flags; /* See set_mempolicy() MPOL_F_* above */ > nodemask_t nodes; /* interleave/bind/perfer */ > @@ -94,7 +95,7 @@ static inline struct mempolicy *mpol_dup(struct mempolicy *pol) > static inline void mpol_get(struct mempolicy *pol) > { > if (pol) > - atomic_inc(&pol->refcnt); > + refcount_inc(&pol->refcnt); > } > > extern bool __mpol_equal(struct mempolicy *a, struct mempolicy *b); > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index e32360e90274..829a14f34b43 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -298,7 +298,7 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, > policy = kmem_cache_alloc(policy_cache, GFP_KERNEL); > if (!policy) > return ERR_PTR(-ENOMEM); > - atomic_set(&policy->refcnt, 1); > + refcount_set(&policy->refcnt, 1); > policy->mode = mode; > policy->flags = flags; > > @@ -308,7 +308,7 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, > /* Slow path of a mpol destructor. */ > void __mpol_put(struct mempolicy *p) > { > - if (!atomic_dec_and_test(&p->refcnt)) > + if (!refcount_dec_and_test(&p->refcnt)) > return; > kmem_cache_free(policy_cache, p); > } > @@ -2290,7 +2290,7 @@ struct mempolicy *__mpol_dup(struct mempolicy *old) > nodemask_t mems = cpuset_mems_allowed(current); > mpol_rebind_policy(new, &mems); > } > - atomic_set(&new->refcnt, 1); > + refcount_set(&new->refcnt, 1); > return new; > } > > @@ -2581,7 +2581,7 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start, > goto alloc_new; > > *mpol_new = *n->policy; > - atomic_set(&mpol_new->refcnt, 1); > + refcount_set(&mpol_new->refcnt, 1); > sp_node_init(n_new, end, n->end, mpol_new); > n->end = start; > sp_insert(sp, n_new); > -- > 2.7.4 >