On Fri, 15 Jul 2011 15:37:43 -0700
Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, 8 Jul 2011 18:06:07 +0930
> Christopher Yeoh <cyeoh@xxxxxxxxxxx> wrote:
>
> > +static ssize_t process_vm_rw(pid_t pid, const struct iovec *lvec,
> > + unsigned long liovcnt,
> > + const struct iovec *rvec,
> > + unsigned long riovcnt,
> > + unsigned long flags, int vm_write)
> > +{
> >
> > ...
> >
> > + if (!mm || (task->flags & PF_KTHREAD)) {
>
> Can a PF_KTHREAD thread have a non-zero ->mm?
> > + task_unlock(task);
> > + rc = -EINVAL;
> > + goto put_task_struct;
> > + }
According to get_task_mm it can:
/**
* get_task_mm - acquire a reference to the task's mm
*
* Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
* this kernel workthread has transiently adopted a user mm with use_mm,
* to do its AIO) is not set and if so returns a reference to it, after
* bumping up the use count. User must release the mm via mmput()
* after use. Typically used by /proc and ptrace.
*/
> anyway, grumble.
>
> Please resend, cc'ing linux-kernel.
Am doing the CC resends in a separate email...
Chris
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