From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: [PATCH v3 49/52] mm, vmstat: Fix CPU hotplug callback registration Date: Tue, 11 Mar 2014 02:12:27 +0530 Message-ID: <20140310204226.10746.64059.stgit@srivatsabhat.in.ibm.com> References: <20140310203312.10746.310.stgit@srivatsabhat.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140310203312.10746.310.stgit@srivatsabhat.in.ibm.com> Sender: owner-linux-mm@kvack.org To: paulus@samba.org, oleg@redhat.com, rjw@rjwysocki.net, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de Cc: paulmck@linux.vnet.ibm.com, tj@kernel.org, walken@google.com, ego@linux.vnet.ibm.com, linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-pm@vger.kernel.org, linuxppc-dev@ozlabs.org, srivatsa.bhat@linux.vnet.ibm.com, Andrew Morton , Johannes Weiner , Cody P Schafer , Toshi Kani , Dave Hansen , Ingo Molnar , linux-mm@kvack.org, Christoph Lameter , Rik van Riel "Srivatsa S. Bhat" List-Id: linux-arch.vger.kernel.org Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_notifier_register_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_notifier_register_done(); Fix the vmstat code in the MM subsystem by using this latter form of callback registration. Cc: Andrew Morton Cc: Johannes Weiner Cc: Cody P Schafer Cc: Toshi Kani Cc: Dave Hansen Cc: Ingo Molnar Cc: linux-mm@kvack.org Acked-by: Christoph Lameter Acked-by: Rik van Riel Reviewed-by: Yasuaki Ishimatsu Signed-off-by: Srivatsa S. Bhat --- mm/vmstat.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/vmstat.c b/mm/vmstat.c index def5dd2..58c6f3d 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1292,14 +1292,14 @@ static int __init setup_vmstat(void) #ifdef CONFIG_SMP int cpu; - register_cpu_notifier(&vmstat_notifier); + cpu_notifier_register_begin(); + __register_cpu_notifier(&vmstat_notifier); - get_online_cpus(); for_each_online_cpu(cpu) { start_cpu_timer(cpu); node_set_state(cpu_to_node(cpu), N_CPU); } - put_online_cpus(); + cpu_notifier_register_done(); #endif #ifdef CONFIG_PROC_FS proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp04.au.ibm.com ([202.81.31.146]:49967 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754197AbaCJUmr (ORCPT ); Mon, 10 Mar 2014 16:42:47 -0400 Received: from /spool/local by e23smtp04.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 11 Mar 2014 06:42:45 +1000 From: "Srivatsa S. Bhat" Subject: [PATCH v3 49/52] mm, vmstat: Fix CPU hotplug callback registration Date: Tue, 11 Mar 2014 02:12:27 +0530 Message-ID: <20140310204226.10746.64059.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140310203312.10746.310.stgit@srivatsabhat.in.ibm.com> References: <20140310203312.10746.310.stgit@srivatsabhat.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: paulus@samba.org, oleg@redhat.com, mingo@kernel.org, rjw@rjwysocki.net, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Cc: paulmck@linux.vnet.ibm.com, tj@kernel.org, walken@google.com, ego@linux.vnet.ibm.com, linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-pm@vger.kernel.org, linuxppc-dev@ozlabs.org, srivatsa.bhat@linux.vnet.ibm.com, Johannes Weiner , Cody P Schafer , Toshi Kani , Dave Hansen , linux-mm@kvack.org, Christoph Lameter , Rik van Riel "Srivatsa S. Bhat" Message-ID: <20140310204227.GWxKmCpZJAW5ipRq9GksnOuGH6QbhWg3j-CQ-aLuso4@z> Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_notifier_register_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_notifier_register_done(); Fix the vmstat code in the MM subsystem by using this latter form of callback registration. Cc: Andrew Morton Cc: Johannes Weiner Cc: Cody P Schafer Cc: Toshi Kani Cc: Dave Hansen Cc: Ingo Molnar Cc: linux-mm@kvack.org Acked-by: Christoph Lameter Acked-by: Rik van Riel Reviewed-by: Yasuaki Ishimatsu Signed-off-by: Srivatsa S. Bhat --- mm/vmstat.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/vmstat.c b/mm/vmstat.c index def5dd2..58c6f3d 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1292,14 +1292,14 @@ static int __init setup_vmstat(void) #ifdef CONFIG_SMP int cpu; - register_cpu_notifier(&vmstat_notifier); + cpu_notifier_register_begin(); + __register_cpu_notifier(&vmstat_notifier); - get_online_cpus(); for_each_online_cpu(cpu) { start_cpu_timer(cpu); node_set_state(cpu_to_node(cpu), N_CPU); } - put_online_cpus(); + cpu_notifier_register_done(); #endif #ifdef CONFIG_PROC_FS proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);