[Utopic][PULL REQ] LP: #1309221

Dann Frazier dann.frazier at canonical.com
Wed Oct 8 15:32:41 UTC 2014


Transparent Huge Pages are currently broken on arm64 and armhf due to
the lack of support for __get_user_pages_fast():

  http://www.spinics.net/lists/linux-mm/msg77628.html

This is easily tickled by gccgo compiled applications, juju in
particularly is a very reliable test case. The fastgup patches were
still going through review during trusty, so we worked around this
issue by disabling THP. These patches have now made their way into
linux-next, and I've prepared a backport to utopic:

      git://kernel.ubuntu.com/dannf/ubuntu-utopic-hyperscale.git@arm-fast-gup

I've tested this on an X-Gene (arm64) board and on an ECX2000
(armhf/a15) board. Both see the hangs (infinite loops) w/o the patches
and both no longer see the problem after these patches are applied.




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