Re: [PATCH] IB/hfi1: Avoid hardlockup with flushlist_lock

On Mon, Jun 24, 2019 at 12:14:29PM -0400, Mike Marciniszyn wrote:

commit cf131a81967583ae737df6383a0893b9fee75b4e upstream.

Heavy contention of the sde flushlist_lock can cause hard lockups at extreme scale when the flushing logic is under stress.

Mitigate by replacing the item at a time copy to the local list with an O(1) list_splice_init() and using the high priority work queue to do the flushes.

Ported to linux-4.14.y.

I've queued this one for 4.19 and 4.14, thank you.

-- Thanks, Sasha