Changes since v1 [1]: - Clarify the failing condition in patch 3 (Michal) - Clarify how subsection collisions manifest in shipping systems (Michal) - Use zone_idx() (Michal) - Move section_taint_zone_device() conditions to move_pfn_range_to_zone() (Michal) - Fix pfn_to_online_page() to account for pfn_valid() vs pfn_section_valid() confusion (David)
[1]: http://lore.kernel.org/r/160990599013.2430134.11556277600719835946.stgit@dwi...
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Michal reminds that the discussion about how to ensure pfn-walkers do not get confused by ZONE_DEVICE pages never resolved. A pfn-walker that uses pfn_to_online_page() may inadvertently translate a pfn as online and in the page allocator, when it is offline managed by a ZONE_DEVICE mapping (details in Patch 3: ("mm: Teach pfn_to_online_page() about ZONE_DEVICE section collisions")).
The 2 proposals under consideration are teach pfn_to_online_page() to be precise in the presence of mixed-zone sections, or teach the memory-add code to drop the System RAM associated with ZONE_DEVICE collisions. In order to not regress memory capacity by a few 10s to 100s of MiB the approach taken in this set is to add precision to pfn_to_online_page().
In the course of validating pfn_to_online_page() a couple other fixes fell out:
1/ soft_offline_page() fails to drop the reference taken in the madvise(..., MADV_SOFT_OFFLINE) case.
2/ The libnvdimm sysfs attribute visibility code was failing to publish the resource base for memmap=ss!nn defined namespaces. This is needed for the regression test for soft_offline_page().
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Dan Williams (5): mm: Move pfn_to_online_page() out of line mm: Teach pfn_to_online_page() to consider subsection validity mm: Teach pfn_to_online_page() about ZONE_DEVICE section collisions mm: Fix page reference leak in soft_offline_page() libnvdimm/namespace: Fix visibility of namespace resource attribute
drivers/nvdimm/namespace_devs.c | 10 +++--- include/linux/memory_hotplug.h | 17 +---------- include/linux/mmzone.h | 22 +++++++++----- mm/memory-failure.c | 20 ++++++++++--- mm/memory_hotplug.c | 62 +++++++++++++++++++++++++++++++++++++++ 5 files changed, 99 insertions(+), 32 deletions(-)