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 DA3ABC433EF for ; Tue, 8 Mar 2022 11:42:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346497AbiCHLnA (ORCPT ); Tue, 8 Mar 2022 06:43:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346531AbiCHLmy (ORCPT ); Tue, 8 Mar 2022 06:42:54 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C74BA2BB0D for ; Tue, 8 Mar 2022 03:41:57 -0800 (PST) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KCYKs57bQzdZMk; Tue, 8 Mar 2022 19:40:33 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Tue, 8 Mar 2022 19:41:54 +0800 Subject: Re: [PATCH 01/16] mm/migration: remove unneeded local variable mapping_locked To: "Huang, Ying" CC: , , , , , , , , , , , , , , , , References: <20220304093409.25829-1-linmiaohe@huawei.com> <20220304093409.25829-2-linmiaohe@huawei.com> <87bkyi7c8f.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Miaohe Lin Message-ID: <8683f5cb-ccd3-ce92-77e0-e0117f405e79@huawei.com> Date: Tue, 8 Mar 2022 19:41:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <87bkyi7c8f.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/3/7 10:00, Huang, Ying wrote: > Miaohe Lin writes: > >> When mapping_locked is true, TTU_RMAP_LOCKED is always set to ttu. We can >> check ttu instead so mapping_locked can be removed. And ttu is either 0 >> or TTU_RMAP_LOCKED now. Change '|=' to '=' to reflect this. >> >> Signed-off-by: Miaohe Lin >> --- >> mm/migrate.c | 6 ++---- >> 1 file changed, 2 insertions(+), 4 deletions(-) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 42e3a944f35c..50bc62d85eaf 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1230,7 +1230,6 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, >> goto put_anon; >> >> if (page_mapped(hpage)) { >> - bool mapping_locked = false; >> enum ttu_flags ttu = 0; >> >> if (!PageAnon(hpage)) { >> @@ -1244,14 +1243,13 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, >> if (unlikely(!mapping)) >> goto unlock_put_anon; >> >> - mapping_locked = true; >> - ttu |= TTU_RMAP_LOCKED; >> + ttu = TTU_RMAP_LOCKED; >> } >> >> try_to_migrate(src, ttu); >> page_was_mapped = 1; >> >> - if (mapping_locked) >> + if (ttu & TTU_RMAP_LOCKED) >> i_mmap_unlock_write(mapping); >> } > > I think this is a code style issue. The original code looks more > readable for me. > I think "ttu |= TTU_RMAP_LOCKED;" is the product of the code changing. And (ttu & TTU_RMAP_LOCKED) can do the right thing as mapping_locked while removing the page_was_mapped. But if you insist on this, I will drop this patch. Thanks. > Best Regards, > Huang, Ying > > . >