On Tue, May 19, 2015 at 11:38 PM, Andrew Morton
[off-list ref] wrote:

On Thu, 14 May 2015 19:30:57 +0200 Andrea Arcangeli [off-list ref] wrote:

quoted

This is the latest userfaultfd patchset against mm-v4.1-rc3
2015-05-14-10:04.

It would be useful to have some userfaultfd testcases in
tools/testing/selftests/.  Partly as an aid to arch maintainers when
enabling this.  And also as a standalone thing to give people a
practical way of exercising this interface.

What are your thoughts on enabling userfaultfd for other architectures,
btw?  Are there good use cases, are people working on it, etc?

UML is using SIGSEGV for page faults.
i.e. the UML processes receives a SIGSEGV, learns the faulting address
from the mcontext
and resolves the fault by installing a new mapping.

If userfaultfd is faster that the SIGSEGV notification it could speed
up UML a bit.
For UML I'm only interested in the notification, not the resolving
part. The "missing"
data is present, only a new mapping is needed. No copy of data.

Andrea, what do you think?

-- 
Thanks,
//richard