s390/pfault: add sanity check
If the task that was found on an initial interrupt doesn't match the
current task execute a WARN_ON_ONCE() and don't put the task to sleep.
When this happened something went wrong between the interface of the
hypervisor and the kernel. In such a case keep the tasks alive to
avoid a hanging system.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index a9c11aa..72cec9e 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -584,6 +584,8 @@
}
} else {
/* signal bit not set -> a real page is missing. */
+ 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);
@@ -606,6 +608,7 @@
set_tsk_need_resched(tsk);
}
}
+out:
spin_unlock(&pfault_lock);
put_task_struct(tsk);
}
