Re: [RFC PATCH v2 2/2] locking/percpu-rwsem: Mark rwsem as non-spinnable in percpu_rwsem_release()

[Peter Zijlstra]

On Mon, May 14, 2018 at 03:31:07PM -0400, Waiman Long wrote:
> The percpu_rwsem_release() is called when the ownership of the embedded
> rwsem is to be transferred to another task. The new owner, however, may
> take a while to get the ownership of the lock via percpu_rwsem_acquire().
> During that period, the rwsem is now marked as writer-owned with no
> optimistic spinning.

This does not explain the problem sufficiently to even begin considering
if the proposed solution is sensible.