The patch titled
cpu hotplug: fix CPU_UP_CANCEL handling
has been added to the -mm tree. Its filename is
cpu-hotplug-fix-cpu_up_cancel-handling.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: cpu hotplug: fix CPU_UP_CANCEL handling
From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
If a cpu hotplug callback fails on CPU_UP_PREPARE, all callbacks will be
called with CPU_UP_CANCELED. A few of these callbacks assume that on
CPU_UP_PREPARE a pointer to task has been stored in a percpu array. This
assumption is not true if CPU_UP_PREPARE fails and the following calls to
kthread_bind() in CPU_UP_CANCELED will cause an addressing exception
because of passing a NULL pointer.
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/sched.c | 2 ++
kernel/softirq.c | 2 ++
kernel/softlockup.c | 2 ++
kernel/workqueue.c | 2 ++
4 files changed, 8 insertions(+)
diff -puN kernel/sched.c~cpu-hotplug-fix-cpu_up_cancel-handling kernel/sched.c
--- a/kernel/sched.c~cpu-hotplug-fix-cpu_up_cancel-handling
+++ a/kernel/sched.c
@@ -4754,6 +4754,8 @@ static int migration_call(struct notifie
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
+ if (!cpu_rq(cpu)->migration_thread)
+ break;
/* Unbind it from offline cpu so it can run. Fall thru. */
kthread_bind(cpu_rq(cpu)->migration_thread,
any_online_cpu(cpu_online_map));
diff -puN kernel/softirq.c~cpu-hotplug-fix-cpu_up_cancel-handling kernel/softirq.c
--- a/kernel/softirq.c~cpu-hotplug-fix-cpu_up_cancel-handling
+++ a/kernel/softirq.c
@@ -470,6 +470,8 @@ static int cpu_callback(struct notifier_
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
+ if (!per_cpu(ksoftirqd, hotcpu))
+ break;
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(ksoftirqd, hotcpu),
any_online_cpu(cpu_online_map));
diff -puN kernel/softlockup.c~cpu-hotplug-fix-cpu_up_cancel-handling kernel/softlockup.c
--- a/kernel/softlockup.c~cpu-hotplug-fix-cpu_up_cancel-handling
+++ a/kernel/softlockup.c
@@ -127,6 +127,8 @@ cpu_callback(struct notifier_block *nfb,
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
+ if (!per_cpu(watchdog_task, hotcpu))
+ break;
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(watchdog_task, hotcpu),
any_online_cpu(cpu_online_map));
diff -puN kernel/workqueue.c~cpu-hotplug-fix-cpu_up_cancel-handling kernel/workqueue.c
--- a/kernel/workqueue.c~cpu-hotplug-fix-cpu_up_cancel-handling
+++ a/kernel/workqueue.c
@@ -590,6 +590,8 @@ static int workqueue_cpu_callback(struct
case CPU_UP_CANCELED:
list_for_each_entry(wq, &workqueues, list) {
+ if (!per_cpu_ptr(wq->cpu_wq, hotcpu)->thread)
+ continue;
/* Unbind so it can run. */
kthread_bind(per_cpu_ptr(wq->cpu_wq, hotcpu)->thread,
any_online_cpu(cpu_online_map));
_
Patches currently in -mm which might be from heiko.carstens@xxxxxxxxxx are
git-klibc.patch
s390-move-var-declarations-behind-ifdef.patch
adjust-handle_irr_event-return-type.patch
add-__iowrite64_copy-s390-fix.patch
kthread-convert-s390machc-from-kernel_thread.patch
cpu-hotplug-fix-cpu_up_cancel-handling.patch
lock-validator-s390-stacktrace-interface.patch
lock-validator-s390-config_frame_pointer-support.patch
lock-validator-s390-rwsem-semaphore-changes.patch
lock-validator-early_init_irq_lock_type--console_init.patch
lock-validator-s390-irqtrace-support.patch
lock-validator-__local_bh_enable-_local_bh_enable.patch
lock-validator-s390-use-raw_spinlock-in-mcck-handler.patch
lock-validator-add-s390-to-supported-options.patch
lockdep-avoid-false-positive-illegal-lock-usage-message-in-qeth-driver.patch
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