Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone

From: Andrea Arcangeli
Date: Wed Aug 02 2017 - 12:40:13 EST

On Wed, Aug 02, 2017 at 06:22:49PM +0200, Michal Hocko wrote:
> ESRCH refers to "no such process". Strictly speaking userfaultfd code is
> about a mm which is gone but that is a mere detail. In fact the owner of

Well this whole issue about which retval, is about a mere detail in
the first place, so I don't think you can discount all other mere
details as irrelevant in the evaluation of a change to solve a mere

> But as I've said, this might be really risky to change. My impression
> was that userfaultfd is not widely used yet and those can be fixed
> easily but if that is not the case then we have to live with the current

The only change would be for userfaultfd non cooperative mode, and
CRIU is the main user of that. So I think it is up to Mike to decide,
I'm fine either ways. I certainly agree ESRCH could be a slightly
better fit, I only wanted to clarify it's not a 100% match either.