On Tue, Feb 12, 2019 at 1:37 PM Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > > Lately Linux has encountered platforms that collide Persistent Memory > regions between each other, specifically cases where ->start_pad needed > to be non-zero. This lead to commit ae86cbfef381 "libnvdimm, pfn: Pad > pfn namespaces relative to other regions". That commit allowed > namespaces to be mapped with devm_memremap_pages(). However dax > operations on those configurations currently fail if attempted within the > ->start_pad range because pmem_device->data_offset was still relative to > raw resource base not relative to the section aligned resource range > mapped by devm_memremap_pages(). > > Luckily __bdev_dax_supported() caught these failures and simply disabled > dax. However, to fix this situation a non-backwards compatible change > needs to be made to the interpretation of the nd_pfn info-block. > ->start_pad needs to be accounted in ->map.map_offset (formerly > ->data_offset), and ->map.map_base (formerly ->phys_addr) needs to be > adjusted to the section aligned resource base used to establish > ->map.map formerly (formerly ->virt_addr). > > See patch 7 "libnvdimm/pfn: Fix 'start_pad' implementation" for more > details, and the ndctl patch series "Improve support + testing for > labels + info-blocks" for the corresponding regression test. Hello valued reviewers, can I plead for a sanity check of at least "libnvdimm/pfn: Introduce super-block minimum version requirements" and "libnvdimm/pfn: Fix 'start_pad' implementation"? In particular Jeff / Johannes this has end user / distro impact in that users may lose access to namespaces that are upgraded to v1.3 info-blocks and then boot an old kernel. I did not see a way around that sharp edge. > --- > > Dan Williams (7): > libnvdimm/pfn: Account for PAGE_SIZE > info-block-size in nd_pfn_init() > libnvdimm/pmem: Honor force_raw for legacy pmem regions > dax: Check the end of the block-device capacity with dax_direct_access() > libnvdimm/pfn: Introduce super-block minimum version requirements > libnvdimm/pfn: Remove dax_label_reserve > libnvdimm/pfn: Introduce 'struct pfn_map_info' > libnvdimm/pfn: Fix 'start_pad' implementation > > > drivers/dax/pmem.c | 9 +- > drivers/dax/super.c | 39 ++++++-- > drivers/nvdimm/namespace_devs.c | 4 + > drivers/nvdimm/nd.h | 15 +++ > drivers/nvdimm/pfn.h | 4 + > drivers/nvdimm/pfn_devs.c | 181 ++++++++++++++++++++++++++++----------- > drivers/nvdimm/pmem.c | 111 +++++++++++------------- > drivers/nvdimm/pmem.h | 12 --- > tools/testing/nvdimm/pmem-dax.c | 15 ++- > 9 files changed, 244 insertions(+), 146 deletions(-)
