Re: [PATCH] gpu: drm: etnaviv: Change return type to vm_fault_t

[Souptick Joarder]

> A non-fatal signal being delivered to a task which is
> in the middle of a page fault may well end up in an
> infinite loop, attempting to handle the page fault and
> failing forever.
>
> On seeing NOPAGE, the fault handler believes the PTE
> is in the page table, so does nothing before it returns
> to arch code. It will end up returning to userspace if
> the signal is non-fatal, at which point it'll go right
> back into the page fault handler, and mutex_lock_interruptible()
> will immediately fail.  So we've converted a sleeping lock
> into the most expensive spinlock.
>
> I don't think the graphics drivers really want to be
> interrupted by any signal.  I think they want to be
> interruptible by fatal signals and should use the
> mutex_lock_killable / fatal_signal_pending family of
> functions. So mutex_lock_interruptible() is replaced
> by mutex_lock_killable()
>

Matthew, are we going to fix similar issues in all drivers
as part of this clean up ?