[0/5] libnvdimm: Cross-arch compatible namespace alignment

Message

Dan Williams Jan. 30, 2020, 8:05 p.m. UTC

Aneesh reports that PowerPC requires 16MiB alignment for the address
range passed to devm_memremap_pages(), and Jeff reports that it is
possible to create a misaligned namespace which blocks future namespace
creation in that region. Both of these issues require namespace
alignment to be managed at the region level rather than padding at the
namespace level which has been a broken approach to date.

Introduce memremap_compat_align() to indicate the hard requirements of
an arch's memremap_pages() implementation. Use the maximum known
memremap_compat_align() to set the default namespace alignment for
libnvdimm. Consult that alignment when allocating free space. Finally,
allow the default region alignment to be overridden to maintain the same
namespace creation capability as previous kernels.

The ndctl unit tests, which have some misaligned namespace assumptions,
are updated to use the alignment override where necessary.

Thanks to Aneesh for early feedback and testing on this improved
alignment handling.

---

Dan Williams (5):
      mm/memremap_pages: Kill unused __devm_memremap_pages()
      mm/memremap_pages: Introduce memremap_compat_align()
      libnvdimm/namespace: Enforce memremap_compat_align()
      libnvdimm/region: Introduce NDD_LABELING
      libnvdimm/region: Introduce an 'align' attribute


 arch/powerpc/include/asm/io.h             |   10 ++
 arch/powerpc/platforms/pseries/papr_scm.c |    2 
 drivers/acpi/nfit/core.c                  |    4 +
 drivers/nvdimm/dimm.c                     |    2 
 drivers/nvdimm/dimm_devs.c                |   95 +++++++++++++++++----
 drivers/nvdimm/namespace_devs.c           |   21 ++++-
 drivers/nvdimm/nd.h                       |    3 -
 drivers/nvdimm/pfn_devs.c                 |    2 
 drivers/nvdimm/region_devs.c              |  132 ++++++++++++++++++++++++++---
 include/linux/io.h                        |   23 +++++
 include/linux/libnvdimm.h                 |    2 
 include/linux/mmzone.h                    |    1 
 12 files changed, 255 insertions(+), 42 deletions(-)