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Diffstat (limited to 'arch/s390/mm/fault.c')
-rw-r--r--arch/s390/mm/fault.c45
1 files changed, 27 insertions, 18 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 46ef3fd0663..72cec9ecd96 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -294,7 +294,7 @@ static inline int do_exception(struct pt_regs *regs, int access)
down_read(&mm->mmap_sem);
#ifdef CONFIG_PGSTE
- if (test_tsk_thread_flag(current, TIF_SIE) && S390_lowcore.gmap) {
+ if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
address = __gmap_fault(address,
(struct gmap *) S390_lowcore.gmap);
if (address == -EFAULT) {
@@ -549,19 +549,15 @@ static void pfault_interrupt(struct ext_code ext_code,
if ((subcode & 0xff00) != __SUBCODE_MASK)
return;
kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++;
- if (subcode & 0x0080) {
- /* Get the token (= pid of the affected task). */
- pid = sizeof(void *) == 4 ? param32 : param64;
- rcu_read_lock();
- tsk = find_task_by_pid_ns(pid, &init_pid_ns);
- if (tsk)
- get_task_struct(tsk);
- rcu_read_unlock();
- if (!tsk)
- return;
- } else {
- tsk = current;
- }
+ /* Get the token (= pid of the affected task). */
+ pid = sizeof(void *) == 4 ? param32 : param64;
+ rcu_read_lock();
+ tsk = find_task_by_pid_ns(pid, &init_pid_ns);
+ if (tsk)
+ get_task_struct(tsk);
+ rcu_read_unlock();
+ if (!tsk)
+ return;
spin_lock(&pfault_lock);
if (subcode & 0x0080) {
/* signal bit is set -> a page has been swapped in by VM */
@@ -574,6 +570,7 @@ static void pfault_interrupt(struct ext_code ext_code,
tsk->thread.pfault_wait = 0;
list_del(&tsk->thread.list);
wake_up_process(tsk);
+ put_task_struct(tsk);
} else {
/* Completion interrupt was faster than initial
* interrupt. Set pfault_wait to -1 so the initial
@@ -585,24 +582,35 @@ static void pfault_interrupt(struct ext_code ext_code,
if (tsk->state == TASK_RUNNING)
tsk->thread.pfault_wait = -1;
}
- put_task_struct(tsk);
} else {
/* signal bit not set -> a real page is missing. */
- if (tsk->thread.pfault_wait == -1) {
+ if (WARN_ON_ONCE(tsk != current))
+ goto out;
+ if (tsk->thread.pfault_wait == 1) {
+ /* Already on the list with a reference: put to sleep */
+ __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+ set_tsk_need_resched(tsk);
+ } else if (tsk->thread.pfault_wait == -1) {
/* Completion interrupt was faster than the initial
* interrupt (pfault_wait == -1). Set pfault_wait
* back to zero and exit. */
tsk->thread.pfault_wait = 0;
} else {
/* Initial interrupt arrived before completion
- * interrupt. Let the task sleep. */
+ * interrupt. Let the task sleep.
+ * An extra task reference is needed since a different
+ * cpu may set the task state to TASK_RUNNING again
+ * before the scheduler is reached. */
+ get_task_struct(tsk);
tsk->thread.pfault_wait = 1;
list_add(&tsk->thread.list, &pfault_list);
- set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+ __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
set_tsk_need_resched(tsk);
}
}
+out:
spin_unlock(&pfault_lock);
+ put_task_struct(tsk);
}
static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
@@ -620,6 +628,7 @@ static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
list_del(&thread->list);
tsk = container_of(thread, struct task_struct, thread);
wake_up_process(tsk);
+ put_task_struct(tsk);
}
spin_unlock_irq(&pfault_lock);
break;