Re: [PATCH] Fix check after use in kernel/exit.c

From: Ingo Molnar
Date: Sat Mar 08 2008 - 03:54:24 EST



* Ingo Molnar <mingo@xxxxxxx> wrote:

> > @@ -582,9 +582,9 @@ static void exit_mm(struct task_struct * tsk)
> > {
> > struct mm_struct *mm = tsk->mm;
> >
> > - mm_release(tsk, mm);
> > if (!mm)
> > return;
> > + mm_release(tsk, mm);
>
> thanks, applied. I'm wondering why this never seems to hit in
> practice.

actually, i unapplied it again because the patch is wrong: mm_release()
has side-effects for kernel threads such as the deactivate_mm() [which
is important even if the user-mm is NULL]. If the NULL mm dereference
can really trigger then it should be avoided within mm_release().

Ingo
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