[PATCH v4 0/2] make ballooned out pages have a valid mapping at all times

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Hi all,
this patch series limits problems caused by tcp retransmits on NFS when
the original block pages were mapped from a foreign domain and now the
mapping is gone.

It accomplishes the goal by:

1) mapping all ballooned out pages to a per-cpu "balloon_scratch_page";
2) making sure that once a grant is unmapped, the original mapping to
the per-cpu balloon_scratch_page is restored atomically.

The first patch accomplishes (1), the second patch uses
GNTTABOP_unmap_and_replace to atomically unmap a grant and restore the
original mapping.



Changes in this version:
- add an early_initcall to clear all the possible per_cpu
  balloon_scratch_page.



Stefano Stabellini (2):
      xen/balloon: set a mapping for ballooned out pages
      xen/m2p: use GNTTABOP_unmap_and_replace to reinstate the original mapping

 arch/x86/xen/p2m.c    |   22 ++++++++++-----
 drivers/xen/balloon.c |   69 ++++++++++++++++++++++++++++++++++++++++++++++--
 drivers/xen/gntdev.c  |   11 +------
 include/xen/balloon.h |    3 ++
 4 files changed, 86 insertions(+), 19 deletions(-)

  git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git valid_mapping_4


Cheers,

Stefano