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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 42E79C433DF for ; Mon, 17 Aug 2020 12:00:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0D4A62067C for ; Mon, 17 Aug 2020 12:00:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0D4A62067C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9AC2E6B0005; Mon, 17 Aug 2020 08:00:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 95C036B0006; Mon, 17 Aug 2020 08:00:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 872D56B0007; Mon, 17 Aug 2020 08:00:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0114.hostedemail.com [216.40.44.114]) by kanga.kvack.org (Postfix) with ESMTP id 6ECBE6B0005 for ; Mon, 17 Aug 2020 08:00:54 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 24C52181AEF3C for ; Mon, 17 Aug 2020 12:00:54 +0000 (UTC) X-FDA: 77159919228.11.bread70_3316d5427016 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin11.hostedemail.com (Postfix) with ESMTP id 2A6D9180F9835 for ; Mon, 17 Aug 2020 12:00:50 +0000 (UTC) X-HE-Tag: bread70_3316d5427016 X-Filterd-Recvd-Size: 1901 Received: from huawei.com (szxga05-in.huawei.com [45.249.212.191]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Mon, 17 Aug 2020 12:00:49 +0000 (UTC) Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 6ADAEE713FB79A561007; Mon, 17 Aug 2020 20:00:44 +0800 (CST) Received: from huawei.com (10.175.104.175) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.487.0; Mon, 17 Aug 2020 20:00:37 +0800 From: Miaohe Lin To: CC: , , Subject: [PATCH] mm/migrate: Avoid possible unnecessary ptrace_may_access() call in kernel_move_pages() Date: Mon, 17 Aug 2020 07:59:33 -0400 Message-ID: <20200817115933.44565-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.104.175] X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 2A6D9180F9835 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: There is no need to check if this process has the right to modify the specified process when they are same. Signed-off-by: Hongxiang Lou Signed-off-by: Miaohe Lin --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index 34a842a8eb6a..342c1ce0b433 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1903,7 +1903,7 @@ static int kernel_move_pages(pid_t pid, unsigned lo= ng nr_pages, * Check if this process has the right to modify the specified * process. Use the regular "ptrace_may_access()" checks. */ - if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { + if (pid && !ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { rcu_read_unlock(); err =3D -EPERM; goto out; --=20 2.19.1