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authorDan Williams <dan.j.williams@intel.com>2019-07-18 15:58:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-18 17:08:07 -0700
commitba72b4c8cf60e452cf6f0258ed9ee697957b7dfd (patch)
tree4e95f72f4fc87e8d8bd69fcf5998e4bb821775ba /include
parent7ea6216049ff9cf250a6722cd766d99c8d1424e5 (diff)
mm/sparsemem: support sub-section hotplug
The libnvdimm sub-system has suffered a series of hacks and broken workarounds for the memory-hotplug implementation's awkward section-aligned (128MB) granularity. For example the following backtrace is emitted when attempting arch_add_memory() with physical address ranges that intersect 'System RAM' (RAM) with 'Persistent Memory' (PMEM) within a given section: # cat /proc/iomem | grep -A1 -B1 Persistent\ Memory 100000000-1ffffffff : System RAM 200000000-303ffffff : Persistent Memory (legacy) 304000000-43fffffff : System RAM 440000000-23ffffffff : Persistent Memory 2400000000-43bfffffff : Persistent Memory 2400000000-43bfffffff : namespace2.0 WARNING: CPU: 38 PID: 928 at arch/x86/mm/init_64.c:850 add_pages+0x5c/0x60 [..] RIP: 0010:add_pages+0x5c/0x60 [..] Call Trace: devm_memremap_pages+0x460/0x6e0 pmem_attach_disk+0x29e/0x680 [nd_pmem] ? nd_dax_probe+0xfc/0x120 [libnvdimm] nvdimm_bus_probe+0x66/0x160 [libnvdimm] It was discovered that the problem goes beyond RAM vs PMEM collisions as some platform produce PMEM vs PMEM collisions within a given section. The libnvdimm workaround for that case revealed that the libnvdimm section-alignment-padding implementation has been broken for a long while. A fix for that long-standing breakage introduces as many problems as it solves as it would require a backward-incompatible change to the namespace metadata interpretation. Instead of that dubious route [1], address the root problem in the memory-hotplug implementation. Note that EEXIST is no longer treated as success as that is how sparse_add_section() reports subsection collisions, it was also obviated by recent changes to perform the request_region() for 'System RAM' before arch_add_memory() in the add_memory() sequence. [1] https://lore.kernel.org/r/155000671719.348031.2347363160141119237.stgit@dwillia2-desk3.amr.corp.intel.com [osalvador@suse.de: fix deactivate_section for early sections] Link: http://lkml.kernel.org/r/20190715081549.32577-2-osalvador@suse.de Link: http://lkml.kernel.org/r/156092354368.979959.6232443923440952359.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Oscar Salvador <osalvador@suse.de> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> [ppc64] Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Logan Gunthorpe <logang@deltatee.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: David Hildenbrand <david@redhat.com> Cc: Jane Chu <jane.chu@oracle.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: Wei Yang <richardw.yang@linux.intel.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/memory_hotplug.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 2d636a7491a4..f46ea71b4ffd 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -348,7 +348,7 @@ extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
extern bool is_memblock_offlined(struct memory_block *mem);
extern int sparse_add_section(int nid, unsigned long pfn,
unsigned long nr_pages, struct vmem_altmap *altmap);
-extern void sparse_remove_one_section(struct mem_section *ms,
+extern void sparse_remove_section(struct mem_section *ms,
unsigned long pfn, unsigned long nr_pages,
unsigned long map_offset, struct vmem_altmap *altmap);
extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,