On Fri, 10 Jul 2015, Jonathan Corbet wrote:

On Thu, 9 Jul 2015 14:46:35 -0400
Eric B Munson [off-list ref] wrote:

quoted

quoted

One other question...if I call mlock2(MLOCK_ONFAULT) on a range that
already has resident pages, I believe that those pages will not be locked
until they are reclaimed and faulted back in again, right?  I suspect that
could be surprising to users.  

That is the case.  I am looking into what it would take to find only the
present pages in a range and lock them, if that is the behavior that is
preferred I can include it in the updated series.

For whatever my $0.02 is worth, I think that should be done.  Otherwise
the mlock2() interface is essentially nondeterministic; you'll never
really know if a specific page is locked or not.

Thanks,

jon

Okay, I likely won't have the new set out today then.  This change is
more invasive.  IIUC, I need an equivalent to __get_user_page() skips
pages which are not present instead of faulting in and the call chain to
get to it.  Unless there is an easier way that I am missing.

Eric