Messages in this thread | | | Date | Mon, 10 Mar 2008 10:13:21 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] Fix check after use in kernel/exit.c |
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* WANG Cong <xiyou.wangcong@gmail.com> wrote:
> --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -583,8 +583,6 @@ static void exit_mm(struct task_struct * tsk) > struct mm_struct *mm = tsk->mm; > > mm_release(tsk, mm); > - if (!mm) > - return;
> @@ -464,6 +464,8 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm) > { > struct completion *vfork_done = tsk->vfork_done; > > + if (!mm) > + return; > /* Get rid of any cached register state */ > deactivate_mm(tsk, mm);
no, this is buggy in the same way - we wont do a deactivate_mm() for kernel threads. The check should be left alone in exit_mm(), we should at most add a check for NULL mm to this place:
if (tsk->clear_child_tid && !(tsk->flags & PF_SIGNALED) && atomic_read(&mm->mm_users) > 1) {
but ... can mm in fact ever be NULL if tsk->clear_child_tid is set?
Ingo
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