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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 A6D7DC2B9F7 for ; Wed, 26 May 2021 05:02:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85CEB613B9 for ; Wed, 26 May 2021 05:02:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231548AbhEZFDn (ORCPT ); Wed, 26 May 2021 01:03:43 -0400 Received: from mga02.intel.com ([134.134.136.20]:50422 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231321AbhEZFDj (ORCPT ); Wed, 26 May 2021 01:03:39 -0400 IronPort-SDR: BilWowgGPVPobMel1FEV0oE8k5F9PImiB8RGfdmPKL1nEhML9SlC0g6aYDnPnc6O1CB56KrNoV w59voX5fXu2g== X-IronPort-AV: E=McAfee;i="6200,9189,9995"; a="189500110" X-IronPort-AV: E=Sophos;i="5.82,330,1613462400"; d="scan'208";a="189500110" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 May 2021 22:01:50 -0700 IronPort-SDR: rHJTpW6ue71FjKcagiwVlhtoj6dWxRqE9aEHOu+VCRNJw6PuzQq0hdq/IBaFGfJO8T2JhV48Jy xCdE/41/iYXw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,330,1613462400"; d="scan'208";a="479700238" Received: from shbuild999.sh.intel.com ([10.239.147.94]) by fmsmga002.fm.intel.com with ESMTP; 25 May 2021 22:01:47 -0700 From: Feng Tang To: linux-mm@kvack.org, Andrew Morton , Michal Hocko , David Rientjes , Dave Hansen , Ben Widawsky Cc: linux-kernel@vger.kernel.org, Andrea Arcangeli , Mel Gorman , Mike Kravetz , Randy Dunlap , Vlastimil Babka , Andi Kleen , Dan Williams , ying.huang@intel.com, Feng Tang Subject: [PATCH v1 1/4] mm/mempolicy: skip nodemask intersect check for 'interleave' when oom Date: Wed, 26 May 2021 13:01:39 +0800 Message-Id: <1622005302-23027-2-git-send-email-feng.tang@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1622005302-23027-1-git-send-email-feng.tang@intel.com> References: <1622005302-23027-1-git-send-email-feng.tang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org mempolicy_nodemask_intersects() is used in oom case to check if a task may have memory allocated on some memory nodes. Currently, the nodes_intersects() is run for both 'bind' and 'interleave' policies. But they are different regarding memory allocation, the nodemask is a forced requirement for 'bind', while just a hint for 'interleave'. Like in alloc_pages_vma(): nmask = policy_nodemask(gfp, pol); preferred_nid = policy_node(gfp, pol, node); page = __alloc_pages(gfp, order, preferred_nid, nmask); in plicy_nodemask(), only 'bind' policy may return its desired nodemask, while others return NULL. And this 'NULL' enables the 'interleave' policy can get memory from other nodes than its nodemask. So skip the nodemask intersect check for 'interleave' policy. Suggested-by: Michal Hocko Signed-off-by: Feng Tang --- mm/mempolicy.c | 24 ++++-------------------- 1 file changed, 4 insertions(+), 20 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index d79fa29..1964cca 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2098,7 +2098,7 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask) * * If tsk's mempolicy is "default" [NULL], return 'true' to indicate default * policy. Otherwise, check for intersection between mask and the policy - * nodemask for 'bind' or 'interleave' policy. For 'preferred' or 'local' + * nodemask for 'bind' policy. For 'interleave', 'preferred' or 'local' * policy, always return true since it may allocate elsewhere on fallback. * * Takes task_lock(tsk) to prevent freeing of its mempolicy. @@ -2111,29 +2111,13 @@ bool mempolicy_nodemask_intersects(struct task_struct *tsk, if (!mask) return ret; + task_lock(tsk); mempolicy = tsk->mempolicy; - if (!mempolicy) - goto out; - - switch (mempolicy->mode) { - case MPOL_PREFERRED: - /* - * MPOL_PREFERRED and MPOL_F_LOCAL are only preferred nodes to - * allocate from, they may fallback to other nodes when oom. - * Thus, it's possible for tsk to have allocated memory from - * nodes in mask. - */ - break; - case MPOL_BIND: - case MPOL_INTERLEAVE: + if (mempolicy && mempolicy->mode == MPOL_BIND) ret = nodes_intersects(mempolicy->v.nodes, *mask); - break; - default: - BUG(); - } -out: task_unlock(tsk); + return ret; } -- 2.7.4