X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=arch%2Fs390%2Fmm%2Ffault.c;h=6903d441068eaad2e012d94cb6eeffd32549cda6;hb=728ae3fd2cd7c9d07c08bb3cca1860df85e8dd77;hp=fe103e891e7a0eb32dc7c67fc0cea3217bd4b6e3;hpb=677ea8d595b6d546394b43a49794d6e9bca1f73d;p=firefly-linux-kernel-4.4.55.git

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index fe103e891e7a..6903d441068e 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -36,7 +36,6 @@
 #include <asm/pgtable.h>
 #include <asm/irq.h>
 #include <asm/mmu_context.h>
-#include <asm/compat.h>
 #include "../kernel/entry.h"
 
 #ifndef CONFIG_64BIT
@@ -568,6 +567,7 @@ static void pfault_interrupt(unsigned int ext_int_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
@@ -577,14 +577,22 @@ static void pfault_interrupt(unsigned int ext_int_code,
 		put_task_struct(tsk);
 	} else {
 		/* signal bit not set -> a real page is missing. */
-		if (tsk->thread.pfault_wait == -1) {
+		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);
@@ -609,6 +617,7 @@ 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;