linux-kernel - [PATCH v4 0/5] libnvdimm: Cross-arch compatible namespace alignment

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Date:   Tue, 03 Mar 2020 18:08:03 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-nvdimm@...ts.01.org
Cc:     Oliver O'Halloran <oohall@...il.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Jeff Moyer <jmoyer@...hat.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v4 0/5] libnvdimm: Cross-arch compatible namespace alignment

Changes since v3 [1]:
- Collect Aneesh's Reviewed-by for Patch1-Patch3

- Add commentary to "libnvdimm/namespace: Enforce
  memremap_compat_align()" to clarify alignment validation and why
  start_pad is deprecated (Aneesh)

[1]: http://lore.kernel.org/r/158291746615.1609624.7591692546429050845.stgit@dwillia2-desk3.amr.corp.intel.com

---

Patch "mm/memremap_pages: Introduce memremap_compat_align()" still
needs a PowerPC maintainer ack for the touches to
arch/powerpc/mm/ioremap.c.

---

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 (modulo dax operation
not being supported with a non-zero start_pad).

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 change to
alignment handling.

---

Dan Williams (5):
      mm/memremap_pages: Introduce memremap_compat_align()
      libnvdimm/pfn: Prevent raw mode fallback if pfn-infoblock valid
      libnvdimm/namespace: Enforce memremap_compat_align()
      libnvdimm/region: Introduce NDD_LABELING
      libnvdimm/region: Introduce an 'align' attribute

 arch/powerpc/Kconfig                      |    1 
 arch/powerpc/mm/ioremap.c                 |   21 +++++
 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           |   28 +++++-
 drivers/nvdimm/nd.h                       |    3 -
 drivers/nvdimm/pfn.h                      |   12 +++
 drivers/nvdimm/pfn_devs.c                 |   40 +++++++--
 drivers/nvdimm/region_devs.c              |  132 ++++++++++++++++++++++++++---
 include/linux/libnvdimm.h                 |    2 
 include/linux/memremap.h                  |    8 ++
 include/linux/mmzone.h                    |    1 
 lib/Kconfig                               |    3 +
 mm/memremap.c                             |   23 +++++
 16 files changed, 330 insertions(+), 47 deletions(-)

base-commit: 1d0827b75ee7df497f611a2ac412a88135fb0ef5