From patchwork Mon Aug 17 11:59:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miaohe Lin X-Patchwork-Id: 11718097 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9F3BA138C 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 7F0A82072E for ; Mon, 17 Aug 2020 12:00:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F0A82072E 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) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 95C036B0006; Mon, 17 Aug 2020 08:00:54 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org 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-Original-To: linux-mm@kvack.org 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-Spam-Summary: 1,0,0,,d41d8cd98f00b204,linmiaohe@huawei.com,,RULES_HIT:30054:30070,0,RBL:45.249.212.191:@huawei.com:.lbl8.mailshell.net-64.95.201.95 62.18.2.100;04yf3isk6kzjjc5ag1a4mw1azeuekopcptbakqgh7ggy8xy6n1oczfhxpyamcm6.hzid1w5879qqk7bs3sz3hf4fi1aa5rk3ntwwbuo7hkgysbyk985rnw3wm4nyzck.n-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:24,LUA_SUMMARY:none 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 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 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 long 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 = -EPERM; goto out;