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=-4.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 08331C10F05 for ; Wed, 20 Mar 2019 22:12:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9F882175B for ; Wed, 20 Mar 2019 22:12:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lca.pw header.i=@lca.pw header.b="SBJeuqyw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727560AbfCTWMn (ORCPT ); Wed, 20 Mar 2019 18:12:43 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:35317 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727382AbfCTWMn (ORCPT ); Wed, 20 Mar 2019 18:12:43 -0400 Received: by mail-qt1-f194.google.com with SMTP id h39so4542032qte.2 for ; Wed, 20 Mar 2019 15:12:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=nX5UkKgqpFczb3/+huvIPo48+SpqyuvBQVCHkeMfnt8=; b=SBJeuqywHpgOVahMOisoAa2/I9E8f2gQd+FLijWp7GI2RoJf5ZaxLc43sjOzJ/zvkG hsGzx63zS3AgqvbSCsWh6prJwzpOGqwORiomJ+qA3N4OpnagGzxk0E4c9+MVPT4elTnw dKLXo4OaWw2r7ZI6g3GEyRUM+k25eTxVeboELeWKtK27qeYZBX6m0Q0ZzLwHqK2qVHdP vle1DkkUd32xbCdUCUmzQrpYvk9K6JPnhG+DrScXCxDKlQJ7R73ULlMDHRDzANM6cUO4 oFSNFjYtZ+WM/npYHyp7l10Vc9tIDvwGFfQ3dIjpOQfhEsXZG7clk98W4BJ8kDM04YW4 Ya9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=nX5UkKgqpFczb3/+huvIPo48+SpqyuvBQVCHkeMfnt8=; b=SsClPrFC+AOKJru8w1DNpB7KTpMHELUmUcc+9Gm26m7D0o9qo7hkKq7aGkDBYzCElG 7/eKMRG2R9eRkj/9PHDeLPTm1Z1cE39+/dMAywM3H6nJwJjOZZN2f0RPKAccYV2OHKpd FojujPe/jh9uNuzR89Xf/rfYs576riOwGCEb4C6UvbEKmN6b34zGbtVT/p5MvtOObVHs yevhtRxykieU8f1PRZa15emuRof0n0mJrBKzV63i9Oir8A0hYoYpddeL56x+p+1QVgIT zdffdfl9xaZFpcLkbvDDzmhidsEc1cP/8gLXrr3np1/RQHZ5tpOeOkjmwKWlef6WLgeK Ngvg== X-Gm-Message-State: APjAAAVC+ebLf8AJimC7Mfla08j63GumznKLYk+mufYpSTfix83ad1rR edLyrUycRYeXSd+gGpRO5Opb3/XuJhQ= X-Google-Smtp-Source: APXvYqw+uT7JrioO/XZkOIfnQXrjn3qFSl531kmhwLmFIuuia9XLfo/TJ7ydD/byQLf6E0mngNQ8Aw== X-Received: by 2002:ac8:3629:: with SMTP id m38mr144460qtb.369.1553119962395; Wed, 20 Mar 2019 15:12:42 -0700 (PDT) Received: from ovpn-120-94.rdu2.redhat.com (pool-71-184-117-43.bstnma.fios.verizon.net. [71.184.117.43]) by smtp.gmail.com with ESMTPSA id d205sm1775689qkg.66.2019.03.20.15.12.41 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Mar 2019 15:12:41 -0700 (PDT) Subject: Re: [RESEND#2 PATCH] mm/compaction: fix an undefined behaviour To: Andrew Morton Cc: mgorman@techsingularity.net, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20190320203338.53367-1-cai@lca.pw> <20190320145826.9c647fe53bd999bbd2ee188d@linux-foundation.org> From: Qian Cai Message-ID: Date: Wed, 20 Mar 2019 18:12:40 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: <20190320145826.9c647fe53bd999bbd2ee188d@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/20/19 5:58 PM, Andrew Morton wrote: >> --- >> mm/compaction.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/mm/compaction.c b/mm/compaction.c >> index e1a08fc92353..0d1156578114 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -1157,7 +1157,9 @@ static bool suitable_migration_target(struct compact_control *cc, >> static inline unsigned int >> freelist_scan_limit(struct compact_control *cc) >> { >> - return (COMPACT_CLUSTER_MAX >> cc->fast_search_fail) + 1; >> + return (COMPACT_CLUSTER_MAX >> >> + min((unsigned short)(BITS_PER_LONG - 1), cc->fast_search_fail)) >> + + 1; >> } > > That's rather an eyesore. How about > > static inline unsigned int > freelist_scan_limit(struct compact_control *cc) > { > unsigned short shift = BITS_PER_LONG - 1; > > return (COMPACT_CLUSTER_MAX >> min(shift, cc->fast_search_fail)) + 1; > } Agree. It looks better.