Hi Pavel

quoted

quoted

As user pages are always in highmem, this should be easy to decide:
only send SIGDANGER when highmem is full. (Yes, there are
inodes/dentries/file descriptors in lowmem, but I doubt apps will
respond to SIGDANGER by closing files).

Good point; for a system with at least (say) 2GB of memory, that
definitely makes sense.  For a system with less than 768 megs of
memory (how quaint, but it wasn't that long ago this was a lot of
memory :-), there wouldn't *be* any memory in highmem at all....

Ok, so it is 'send SIGDANGER when all zones are low', because user
allocations can go from all zones (unless you have something really
exotic, I'm not sure if that is true on huge NUMA  machines & similar).

thank you good point out.

to be honest, the zone awareness of current mem_notify is premature.
I think we need enhancement rss statistics to per zone rss.
but not implemented yet ;-)

and, unfortunately I have no highmem machine.
the mem_notify is not so tested on highmem machine.

if you help to test, I am very happy!
Thanks.