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 9FE85C77B76 for ; Tue, 18 Apr 2023 12:36:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231733AbjDRMgm (ORCPT ); Tue, 18 Apr 2023 08:36:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231723AbjDRMgl (ORCPT ); Tue, 18 Apr 2023 08:36:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8634F12C93 for ; Tue, 18 Apr 2023 05:36:39 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 123F66329D for ; Tue, 18 Apr 2023 12:36:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25A4EC4339B; Tue, 18 Apr 2023 12:36:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681821398; bh=Q8RWFHbSW+5hPnOz1GH2LlvuuSmZsbpztsw5AK906Uw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gq1xg55K8IgXE6V9RmZ+6H8a5KQnv0ma9X0Bcv5FuL/164wGecm2zYybuTXM6CsjY YLfHdaaEQoo2dL3L973LmixNBylHgNURHUOorzOn7h1oTJsVRRtOk5LpjLQjDo12w6 oWSJxs9F7v5SMCfQUhXCPxBzQA9Ev04fb6PudhXI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Waiman Long , Tejun Heo Subject: [PATCH 5.10 111/124] cgroup/cpuset: Change references of cpuset_mutex to cpuset_rwsem Date: Tue, 18 Apr 2023 14:22:10 +0200 Message-Id: <20230418120313.827182358@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230418120309.539243408@linuxfoundation.org> References: <20230418120309.539243408@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Waiman Long Commit b94f9ac79a7395c2d6171cc753cc27942df0be73 upstream. Since commit 1243dc518c9d ("cgroup/cpuset: Convert cpuset_mutex to percpu_rwsem"), cpuset_mutex has been replaced by cpuset_rwsem which is a percpu rwsem. However, the comments in kernel/cgroup/cpuset.c still reference cpuset_mutex which are now incorrect. Change all the references of cpuset_mutex to cpuset_rwsem. Fixes: 1243dc518c9d ("cgroup/cpuset: Convert cpuset_mutex to percpu_rwsem") Signed-off-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/cpuset.c | 56 +++++++++++++++++++++++++------------------------ 1 file changed, 29 insertions(+), 27 deletions(-) --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -299,17 +299,19 @@ static struct cpuset top_cpuset = { if (is_cpuset_online(((des_cs) = css_cs((pos_css))))) /* - * There are two global locks guarding cpuset structures - cpuset_mutex and + * There are two global locks guarding cpuset structures - cpuset_rwsem and * callback_lock. We also require taking task_lock() when dereferencing a * task's cpuset pointer. See "The task_lock() exception", at the end of this - * comment. + * comment. The cpuset code uses only cpuset_rwsem write lock. Other + * kernel subsystems can use cpuset_read_lock()/cpuset_read_unlock() to + * prevent change to cpuset structures. * * A task must hold both locks to modify cpusets. If a task holds - * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it + * cpuset_rwsem, it blocks others wanting that rwsem, ensuring that it * is the only task able to also acquire callback_lock and be able to * modify cpusets. It can perform various checks on the cpuset structure * first, knowing nothing will change. It can also allocate memory while - * just holding cpuset_mutex. While it is performing these checks, various + * just holding cpuset_rwsem. While it is performing these checks, various * callback routines can briefly acquire callback_lock to query cpusets. * Once it is ready to make the changes, it takes callback_lock, blocking * everyone else. @@ -380,7 +382,7 @@ static inline bool is_in_v2_mode(void) * One way or another, we guarantee to return some non-empty subset * of cpu_online_mask. * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) { @@ -410,7 +412,7 @@ static void guarantee_online_cpus(struct * One way or another, we guarantee to return some non-empty subset * of node_states[N_MEMORY]. * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask) { @@ -422,7 +424,7 @@ static void guarantee_online_mems(struct /* * update task's spread flag if cpuset's page/slab spread flag is set * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ static void cpuset_update_task_spread_flag(struct cpuset *cs, struct task_struct *tsk) @@ -443,7 +445,7 @@ static void cpuset_update_task_spread_fl * * One cpuset is a subset of another if all its allowed CPUs and * Memory Nodes are a subset of the other, and its exclusive flags - * are only set if the other's are set. Call holding cpuset_mutex. + * are only set if the other's are set. Call holding cpuset_rwsem. */ static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) @@ -552,7 +554,7 @@ static inline void free_cpuset(struct cp * If we replaced the flag and mask values of the current cpuset * (cur) with those values in the trial cpuset (trial), would * our various subset and exclusive rules still be valid? Presumes - * cpuset_mutex held. + * cpuset_rwsem held. * * 'cur' is the address of an actual, in-use cpuset. Operations * such as list traversal that depend on the actual address of the @@ -675,7 +677,7 @@ static void update_domain_attr_tree(stru rcu_read_unlock(); } -/* Must be called with cpuset_mutex held. */ +/* Must be called with cpuset_rwsem held. */ static inline int nr_cpusets(void) { /* jump label reference count + the top-level cpuset */ @@ -701,7 +703,7 @@ static inline int nr_cpusets(void) * domains when operating in the severe memory shortage situations * that could cause allocation failures below. * - * Must be called with cpuset_mutex held. + * Must be called with cpuset_rwsem held. * * The three key local variables below are: * cp - cpuset pointer, used (together with pos_css) to perform a @@ -980,7 +982,7 @@ partition_and_rebuild_sched_domains(int * 'cpus' is removed, then call this routine to rebuild the * scheduler's dynamic sched domains. * - * Call with cpuset_mutex held. Takes get_online_cpus(). + * Call with cpuset_rwsem held. Takes get_online_cpus(). */ static void rebuild_sched_domains_locked(void) { @@ -1053,7 +1055,7 @@ void rebuild_sched_domains(void) * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed * * Iterate through each task of @cs updating its cpus_allowed to the - * effective cpuset's. As this function is called with cpuset_mutex held, + * effective cpuset's. As this function is called with cpuset_rwsem held, * cpuset membership stays stable. */ static void update_tasks_cpumask(struct cpuset *cs) @@ -1328,7 +1330,7 @@ static int update_parent_subparts_cpumas * * On legacy hierachy, effective_cpus will be the same with cpu_allowed. * - * Called with cpuset_mutex held + * Called with cpuset_rwsem held */ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) { @@ -1688,12 +1690,12 @@ static void *cpuset_being_rebound; * @cs: the cpuset in which each task's mems_allowed mask needs to be changed * * Iterate through each task of @cs updating its mems_allowed to the - * effective cpuset's. As this function is called with cpuset_mutex held, + * effective cpuset's. As this function is called with cpuset_rwsem held, * cpuset membership stays stable. */ static void update_tasks_nodemask(struct cpuset *cs) { - static nodemask_t newmems; /* protected by cpuset_mutex */ + static nodemask_t newmems; /* protected by cpuset_rwsem */ struct css_task_iter it; struct task_struct *task; @@ -1706,7 +1708,7 @@ static void update_tasks_nodemask(struct * take while holding tasklist_lock. Forks can happen - the * mpol_dup() cpuset_being_rebound check will catch such forks, * and rebind their vma mempolicies too. Because we still hold - * the global cpuset_mutex, we know that no other rebind effort + * the global cpuset_rwsem, we know that no other rebind effort * will be contending for the global variable cpuset_being_rebound. * It's ok if we rebind the same mm twice; mpol_rebind_mm() * is idempotent. Also migrate pages in each mm to new nodes. @@ -1752,7 +1754,7 @@ static void update_tasks_nodemask(struct * * On legacy hiearchy, effective_mems will be the same with mems_allowed. * - * Called with cpuset_mutex held + * Called with cpuset_rwsem held */ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) { @@ -1805,7 +1807,7 @@ static void update_nodemasks_hier(struct * mempolicies and if the cpuset is marked 'memory_migrate', * migrate the tasks pages to the new memory. * - * Call with cpuset_mutex held. May take callback_lock during call. + * Call with cpuset_rwsem held. May take callback_lock during call. * Will take tasklist_lock, scan tasklist for tasks in cpuset cs, * lock each such tasks mm->mmap_lock, scan its vma's and rebind * their mempolicies to the cpusets new mems_allowed. @@ -1895,7 +1897,7 @@ static int update_relax_domain_level(str * @cs: the cpuset in which each task's spread flags needs to be changed * * Iterate through each task of @cs updating its spread flags. As this - * function is called with cpuset_mutex held, cpuset membership stays + * function is called with cpuset_rwsem held, cpuset membership stays * stable. */ static void update_tasks_flags(struct cpuset *cs) @@ -1915,7 +1917,7 @@ static void update_tasks_flags(struct cp * cs: the cpuset to update * turning_on: whether the flag is being set or cleared * - * Call with cpuset_mutex held. + * Call with cpuset_rwsem held. */ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, @@ -1964,7 +1966,7 @@ out: * cs: the cpuset to update * new_prs: new partition root state * - * Call with cpuset_mutex held. + * Call with cpuset_rwsem held. */ static int update_prstate(struct cpuset *cs, int new_prs) { @@ -2145,7 +2147,7 @@ static int fmeter_getrate(struct fmeter static struct cpuset *cpuset_attach_old_cs; -/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */ +/* Called by cgroups to determine if a cpuset is usable; cpuset_rwsem held */ static int cpuset_can_attach(struct cgroup_taskset *tset) { struct cgroup_subsys_state *css; @@ -2201,7 +2203,7 @@ static void cpuset_cancel_attach(struct } /* - * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach() + * Protected by cpuset_rwsem. cpus_attach is used only by cpuset_attach() * but we can't allocate it dynamically there. Define it global and * allocate from cpuset_init(). */ @@ -2209,7 +2211,7 @@ static cpumask_var_t cpus_attach; static void cpuset_attach(struct cgroup_taskset *tset) { - /* static buf protected by cpuset_mutex */ + /* static buf protected by cpuset_rwsem */ static nodemask_t cpuset_attach_nodemask_to; struct task_struct *task; struct task_struct *leader; @@ -2402,7 +2404,7 @@ static ssize_t cpuset_write_resmask(stru * operation like this one can lead to a deadlock through kernfs * active_ref protection. Let's break the protection. Losing the * protection is okay as we check whether @cs is online after - * grabbing cpuset_mutex anyway. This only happens on the legacy + * grabbing cpuset_rwsem anyway. This only happens on the legacy * hierarchies. */ css_get(&cs->css); @@ -3641,7 +3643,7 @@ void __cpuset_memory_pressure_bump(void) * - Used for /proc//cpuset. * - No need to task_lock(tsk) on this tsk->cpuset reference, as it * doesn't really matter if tsk->cpuset changes after we read it, - * and we take cpuset_mutex, keeping cpuset_attach() from changing it + * and we take cpuset_rwsem, keeping cpuset_attach() from changing it * anyway. */ int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,