From patchwork Wed Aug 19 08:33:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miaohe Lin X-Patchwork-Id: 11723271 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 0695714F6 for ; Wed, 19 Aug 2020 08:34:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CD3BA207DE for ; Wed, 19 Aug 2020 08:34:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CD3BA207DE 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 F3F8C8D0011; Wed, 19 Aug 2020 04:34:53 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id E9FB56B0074; Wed, 19 Aug 2020 04:34:53 -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 D19708D0011; Wed, 19 Aug 2020 04:34:53 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0032.hostedemail.com [216.40.44.32]) by kanga.kvack.org (Postfix) with ESMTP id B6E8F6B0073 for ; Wed, 19 Aug 2020 04:34:53 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 772E3247A for ; Wed, 19 Aug 2020 08:34:53 +0000 (UTC) X-FDA: 77166657666.20.rub56_181480127026 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id 53432180C07A3 for ; Wed, 19 Aug 2020 08:34:53 +0000 (UTC) X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,linmiaohe@huawei.com,,RULES_HIT:30046:30051:30054:30070,0,RBL:45.249.212.191:@huawei.com:.lbl8.mailshell.net-64.95.201.95 62.18.2.100;04yr5qnn9zdms4b83roux1mmzhyccopwabco3ftck3fbj4h6ntayywk9cxgjmio.nthpxnyyhnoapbc4odomusr61k3wyp1e8yweih5w4qz4wtkinizkp49e13ir6wj.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:23,LUA_SUMMARY:none X-HE-Tag: rub56_181480127026 X-Filterd-Recvd-Size: 4611 Received: from huawei.com (szxga05-in.huawei.com [45.249.212.191]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Wed, 19 Aug 2020 08:34:51 +0000 (UTC) Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id BBB24E4CCA2E7D39B94A; Wed, 19 Aug 2020 16:34:44 +0800 (CST) Received: from huawei.com (10.175.104.175) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.487.0; Wed, 19 Aug 2020 16:34:37 +0800 From: Miaohe Lin To: CC: , , , Subject: [PATCH v2] mm/migrate: Avoid possible unnecessary process right check in kernel_move_pages() Date: Wed, 19 Aug 2020 04:33:31 -0400 Message-ID: <20200819083331.19012-1-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: 53432180C07A3 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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. And we could also skip the security hook call if a process is modifying its own pages. Add helper function to handle these. Suggested-by: Matthew Wilcox Signed-off-by: Hongxiang Lou Signed-off-by: Miaohe Lin --- mm/migrate.c | 71 +++++++++++++++++++++++++++++++--------------------- 1 file changed, 43 insertions(+), 28 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 34a842a8eb6a..9026876a27dc 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1869,33 +1869,27 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, return nr_pages ? -EFAULT : 0; } -/* - * Move a list of pages in the address space of the currently executing - * process. - */ -static int kernel_move_pages(pid_t pid, unsigned long nr_pages, - const void __user * __user *pages, - const int __user *nodes, - int __user *status, int flags) +static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes) { struct task_struct *task; struct mm_struct *mm; - int err; - nodemask_t task_nodes; - - /* Check flags */ - if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) - return -EINVAL; - if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) - return -EPERM; + /* + * There is no need to check if current process has the right to modify + * the specified process when they are same. + */ + if (!pid) { + mmget(current->mm); + *mem_nodes = cpuset_mems_allowed(current); + return current->mm; + } /* Find the mm_struct */ rcu_read_lock(); - task = pid ? find_task_by_vpid(pid) : current; + task = find_task_by_vpid(pid); if (!task) { rcu_read_unlock(); - return -ESRCH; + return ERR_PTR(-ESRCH); } get_task_struct(task); @@ -1905,22 +1899,47 @@ static int kernel_move_pages(pid_t pid, unsigned long nr_pages, */ if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { rcu_read_unlock(); - err = -EPERM; + mm = ERR_PTR(-EPERM); goto out; } rcu_read_unlock(); - err = security_task_movememory(task); - if (err) + mm = ERR_PTR(security_task_movememory(task)); + if (IS_ERR(mm)) goto out; - - task_nodes = cpuset_mems_allowed(task); + *mem_nodes = cpuset_mems_allowed(task); mm = get_task_mm(task); +out: put_task_struct(task); - if (!mm) + mm = ERR_PTR(-EINVAL); + return mm; +} + +/* + * Move a list of pages in the address space of the currently executing + * process. + */ +static int kernel_move_pages(pid_t pid, unsigned long nr_pages, + const void __user * __user *pages, + const int __user *nodes, + int __user *status, int flags) +{ + struct mm_struct *mm; + int err; + nodemask_t task_nodes; + + /* Check flags */ + if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) return -EINVAL; + if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) + return -EPERM; + + mm = find_mm_struct(pid, &task_nodes); + if (IS_ERR(mm)) + return PTR_ERR(mm); + if (nodes) err = do_pages_move(mm, task_nodes, nr_pages, pages, nodes, status, flags); @@ -1929,10 +1948,6 @@ static int kernel_move_pages(pid_t pid, unsigned long nr_pages, mmput(mm); return err; - -out: - put_task_struct(task); - return err; } SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,