On Thu, Aug 03, 2017 at 08:24:43PM +0300, Mike Rapoport wrote: > Now, seriously, I believe there are not many users of non-cooperative uffd > if at all and it is very unlikely anybody has it in production. > > I'll send a patch with s/ENOSPC/ESRCH in the next few days. Ok. Some more thought on this one, enterprise kernels have been shipped matching the v4.11-v4.12 upstream kernel ABI and I've no time machine to alter the kABI on those installs. If you go ahead with the change, the safest would be that you keep handling -ENOSPC and -ESRCH equally in CRIU code, so there will be no risk of regression in the short term if somebody is playing with an upstream CRIU. The alternative would be add uname -r knowledge. Once it's upstream, I can fixup so further kernel updates will go in sync. I obviously can't make changes that affects the kABI until it's upstream and shipped in a official release so things will be out of sync for a while (and the risk of somebody using ancient kernels will persist for the mid term).