On 03/30/2011 05:52 PM, Benjamin Herrenschmidt wrote:

We deal with preemption already since the PTL turns into a mutex on -rt,
so we could bring that patch into mainline. The easiest approach however
for now would be to not do the kernel batched updates on kernel
(solution 4), and I can sort it out later if I want to enable it.

The problem is that it's hard for me to "fix" that with the current
accessors as arch_enter_lazy_mmu_mode() don't get any argument that
could point me to which mm is being operated on.

Jeremy, I haven't had a chance to look at your patches in detail, do
you just use those accessors or do you create new ones for batching
kernel updates in which case powerpc could just make them do nothing ?

Else, we could have one patch that adds an mm argument accross the tree,
it shouldn't be too hard.

No, its the same accessors for both, since the need to distinguish them
hasn't really come up.  Could you put a "if (preemptable()) return;"
guard in your implementations?

Otherwise I have no objections to passing the mm in (we'll probably just
continue to ignore the arg in x86-land).

Thanks,
    J