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[2620:137:e000::1:20]) by mx.google.com with ESMTP id jt24-20020a170906dfd800b008c85af719fasi14265330ejc.435.2023.03.08.05.28.53; Wed, 08 Mar 2023 05:29:17 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=eTJmEafz; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231192AbjCHNTL (ORCPT + 99 others); Wed, 8 Mar 2023 08:19:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231521AbjCHNSc (ORCPT ); Wed, 8 Mar 2023 08:18:32 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1EE52CB644 for ; Wed, 8 Mar 2023 05:15:12 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id x64-20020a25ce43000000b00ae6d5855d78so17677021ybe.12 for ; Wed, 08 Mar 2023 05:15:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1678281310; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=V2OWyyThXDzCsX5dfUI5J1YeLCRnmlzAhR0ONAX2q6c=; b=eTJmEafz02AisZ86AJ7inkOANlOT7YZR4TTp+I8VfysjvCRHGV5+hEnzifTlMdyGnd 1OkVVwur8jZvZfVKIvD9VHxyoxfNZEWw1qiuj//mPyrwtI323ZqXudRxscC6NcGUtt9b GDzRFPzvXF0f2MuhwNCeMubC3iMwCqqYks0OA45nqs6alr9+UIhzN7PqRl0AuWDC1kxp ycCyhtGuklso+a7joCnePh3oGkgMoZo6lWkkVwoITX1ged6hCbxieBiPNl5k6yU0jsIk rlMQrW3UihIYZXRc4Z8pIymKbVqitmmzsBaf730S9iTB6LkkSdR2FLCe2X0Blqklm6FH oy+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678281310; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=V2OWyyThXDzCsX5dfUI5J1YeLCRnmlzAhR0ONAX2q6c=; b=7Kn2Qwpg9p6KvdDXS482GVbWPHPRDZ+iS8Q/hiK0PWPO4xX0WheQ68z5RoQIQ1cH32 Wr4nnDCYKzmqA4ThW05BEHg7TThiXFdm9ObvMrCZVYA6gQDRgtTlyVpAt3mRTp4Vf7sA 1Lxnxa4w+ikqNNEr7vCscJZLKSaF2hnSYVBhbIfe47vdnUgzpbL6b/6/Qym6sPjWqmtq ygZKIMVhGN4OYxdzqMcPwNrAh/thKUwWh5AqR90ISFdtKkFWAjgl7a6chO+ERceDP4th Km1FgKdnd4JoM4bDR22OaCUKwouvUjOqUwYWanJj77JbCteby8N7w8jTxgoXl+S3lqIS waZw== X-Gm-Message-State: AO0yUKWNwUJ5gnHrPdxuOfkp8WJwNOa4UMuEVelM9+O3m+8RroRFhPud SMIXYbdgJoRobkKF4QkKRh9SOsmyXRKKM4AqLQ== X-Received: from peternewman-vh.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:30cc]) (user=peternewman job=sendgmr) by 2002:a05:6902:10e:b0:98e:6280:74ca with SMTP id o14-20020a056902010e00b0098e628074camr8955336ybh.1.1678281310581; Wed, 08 Mar 2023 05:15:10 -0800 (PST) Date: Wed, 8 Mar 2023 14:14:52 +0100 In-Reply-To: <20230308131452.383914-1-peternewman@google.com> Mime-Version: 1.0 References: <20230308131452.383914-1-peternewman@google.com> X-Mailer: git-send-email 2.40.0.rc0.216.gc4246ad0f0-goog Message-ID: <20230308131452.383914-4-peternewman@google.com> Subject: [PATCH v4 3/3] x86/resctrl: Implement rename op for mon groups From: Peter Newman To: reinette.chatre@intel.com, fenghua.yu@intel.com Cc: Babu.Moger@amd.com, bp@alien8.de, dave.hansen@linux.intel.com, eranian@google.com, gupasani@google.com, hpa@zytor.com, james.morse@arm.com, linux-kernel@vger.kernel.org, mingo@redhat.com, skodak@google.com, tglx@linutronix.de, tony.luck@intel.com, x86@kernel.org, Peter Newman X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1759806391069898286?= X-GMAIL-MSGID: =?utf-8?q?1759806391069898286?= To change the class of service for a large group of tasks, such as an application container, a container manager must write all of the tasks' IDs into the tasks file interface of the new control group. If a container manager is tracking containers' bandwidth usage by placing tasks from each into their own monitoring group, it must first move the tasks to the default monitoring group of the new control group before it can move the tasks into their new monitoring groups. This is undesirable because it makes bandwidth usage during the move unattributable to the correct tasks and resets monitoring event counters and cache usage information for the group. To address this, implement the rename operation for resctrlfs mon groups to effect a change in CLOSID for a MON group while otherwise leaving the monitoring group intact. Signed-off-by: Peter Newman --- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 127 +++++++++++++++++++++++++ 1 file changed, 127 insertions(+) diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 84af23a29612..6d576013fc16 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -3256,6 +3256,132 @@ static int rdtgroup_rmdir(struct kernfs_node *kn) return ret; } +static bool mongrp_reparent_match(struct task_struct *t, struct rdtgroup *from) +{ + WARN_ON(from->type != RDTMON_GROUP); + + /* RMID match implies CLOSID match. */ + return is_rmid_match(t, from); +} + +/** + * mongrp_reparent() - replace parent CTRL_MON group of a MON group + * @rdtgrp: the MON group whose parent should be replaced + * @new_prdtgrp: replacement parent CTRL_MON group for @rdtgrp + * @cpus: cpumask provided by the caller for use during this call + * + * Replaces the parent CTRL_MON group for a MON group, resulting in all member + * tasks' CLOSID immediately changing to that of the new parent group. + * Monitoring data for the group is unaffected by this operation. + */ +static void mongrp_reparent(struct rdtgroup *rdtgrp, + struct rdtgroup *new_prdtgrp, + cpumask_var_t cpus) +{ + struct rdtgroup *prdtgrp = rdtgrp->mon.parent; + + WARN_ON(rdtgrp->type != RDTMON_GROUP); + WARN_ON(new_prdtgrp->type != RDTCTRL_GROUP); + + /* Nothing to do when simply renaming a MON group. */ + if (prdtgrp == new_prdtgrp) + return; + + WARN_ON(list_empty(&prdtgrp->mon.crdtgrp_list)); + list_del(&rdtgrp->mon.crdtgrp_list); + + list_add_tail(&rdtgrp->mon.crdtgrp_list, + &new_prdtgrp->mon.crdtgrp_list); + rdtgrp->mon.parent = new_prdtgrp; + rdtgrp->closid = new_prdtgrp->closid; + + /* Propagate updated closid to all tasks in this group. */ + rdt_move_group_tasks(rdtgrp, rdtgrp, cpus, mongrp_reparent_match); + + update_closid_rmid(cpus, NULL); +} + +static int rdtgroup_rename(struct kernfs_node *kn, + struct kernfs_node *new_parent, const char *new_name) +{ + struct rdtgroup *new_prdtgrp; + struct rdtgroup *rdtgrp; + cpumask_var_t tmpmask; + int ret; + + /* + * Don't allow kernfs_to_rdtgroup() to return a parent rdtgroup if + * either kernfs_node is a file. + */ + if (kernfs_type(kn) != KERNFS_DIR || + kernfs_type(new_parent) != KERNFS_DIR) + return -EPERM; + + rdtgrp = kernfs_to_rdtgroup(kn); + new_prdtgrp = kernfs_to_rdtgroup(new_parent); + if (!rdtgrp || !new_prdtgrp) + return -EPERM; + + if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL)) + return -ENOMEM; + + /* Release both kernfs active_refs before obtaining rdtgroup mutex. */ + rdtgroup_kn_get(rdtgrp, kn); + rdtgroup_kn_get(new_prdtgrp, new_parent); + + mutex_lock(&rdtgroup_mutex); + + rdt_last_cmd_clear(); + + if ((rdtgrp->flags & RDT_DELETED) || (new_prdtgrp->flags & RDT_DELETED)) { + ret = -ESRCH; + goto out; + } + + if (rdtgrp->type != RDTMON_GROUP || !kn->parent || + !is_mon_groups(kn->parent, kn->name)) { + rdt_last_cmd_puts("source must be a MON group\n"); + ret = -EPERM; + goto out; + } + + if (!is_mon_groups(new_parent, new_name)) { + rdt_last_cmd_puts("destination must be a mon_groups subdirectory\n"); + ret = -EPERM; + goto out; + } + + /* + * If the MON group is monitoring CPUs, they must be assigned to the + * current parent CTRL_MON group and therefore cannot be assigned to + * the new parent, making the move illegal. + */ + if (!cpumask_empty(&rdtgrp->cpu_mask) && + (rdtgrp->mon.parent != new_prdtgrp)) { + rdt_last_cmd_puts("cannot move a MON group that monitors CPUs\n"); + ret = -EPERM; + goto out; + } + + /* + * Perform all input validation needed to ensure mongrp_reparent() will + * succeed before calling kernfs_rename(), otherwise it would be + * necessary to revert this call if mongrp_reparent() failed. + */ + ret = kernfs_rename(kn, new_parent, new_name); + if (ret) + goto out; + + mongrp_reparent(rdtgrp, new_prdtgrp, tmpmask); + +out: + mutex_unlock(&rdtgroup_mutex); + rdtgroup_kn_put(rdtgrp, kn); + rdtgroup_kn_put(new_prdtgrp, new_parent); + free_cpumask_var(tmpmask); + return ret; +} + static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf) { if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L3)) @@ -3273,6 +3399,7 @@ static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf) static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = { .mkdir = rdtgroup_mkdir, .rmdir = rdtgroup_rmdir, + .rename = rdtgroup_rename, .show_options = rdtgroup_show_options, };