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s390/pfault: add sanity check

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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>
This commit is contained in:
Heiko Carstens 2012-05-10 10:47:21 +02:00 committed by Martin Schwidefsky
parent 0a16ba7866
commit d49f47f83d
1 changed files with 3 additions and 0 deletions
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3
arch/s390/mm/fault.c
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@ -584,6 +584,8 @@ static void pfault_interrupt(struct ext_code ext_code,
} }
} else { } else {
/* signal bit not set -> a real page is missing. */ /* signal bit not set -> a real page is missing. */
if (WARN_ON_ONCE(tsk != current))
goto out;
if (tsk->thread.pfault_wait == 1) { if (tsk->thread.pfault_wait == 1) {
/* Already on the list with a reference: put to sleep */ /* Already on the list with a reference: put to sleep */
__set_task_state(tsk, TASK_UNINTERRUPTIBLE); __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
@ -606,6 +608,7 @@ static void pfault_interrupt(struct ext_code ext_code,
set_tsk_need_resched(tsk); set_tsk_need_resched(tsk);
} }
} }
out:
spin_unlock(&pfault_lock); spin_unlock(&pfault_lock);
put_task_struct(tsk); put_task_struct(tsk);
} }