Re: [PATCH 4/4] mm, notifier: Catch sleeping/blocking for !blockable
From: Jason Gunthorpe
Date: Thu Aug 22 2019 - 10:24:16 EST
On Thu, Aug 22, 2019 at 10:42:39AM +0200, Daniel Vetter wrote:
> > RDMA has a mutex:
> > ib_umem_notifier_invalidate_range_end
> > rbt_ib_umem_for_each_in_range
> > invalidate_range_start_trampoline
> > ib_umem_notifier_end_account
> > mutex_lock(&umem_odp->umem_mutex);
> > I'm working to delete this path though!
> > nonblocking or not follows the start, the same flag gets placed into
> > the mmu_notifier_range struct passed to end.
> Ok, makes sense.
> I guess that also means the might_sleep (I started on that) in
> invalidate_range_end also needs to be conditional? Or not bother with
> a might_sleep in invalidate_range_end since you're working on removing
> the last sleep in there?
I might suggest the same pattern as used for locked, the might_sleep
unconditionally on the start, and a 2nd might sleep after the IF in
Observing that by audit all the callers already have the same locking
context for start/end