path: root/mm/memory_hotplug.c
diff options
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 /mm/memory_hotplug.c
parentmm/sparsemem: prepare for sub-section ranges (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 '')
1 files changed, 4 insertions, 23 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3fbb2cfab126..aafb71594ee3 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -252,18 +252,6 @@ void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
-static int __meminit __add_section(int nid, unsigned long pfn,
- unsigned long nr_pages, struct vmem_altmap *altmap)
- int ret;
- if (pfn_valid(pfn))
- return -EEXIST;
- ret = sparse_add_section(nid, pfn, nr_pages, altmap);
- return ret < 0 ? ret : 0;
static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
const char *reason)
@@ -327,18 +315,11 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
pfns = min(nr_pages, PAGES_PER_SECTION
- (pfn & ~PAGE_SECTION_MASK));
- err = __add_section(nid, pfn, pfns, altmap);
+ err = sparse_add_section(nid, pfn, pfns, altmap);
+ if (err)
+ break;
pfn += pfns;
nr_pages -= pfns;
- /*
- * EEXIST is finally dealt with by ioresource collision
- * check. see add_memory() => register_memory_resource()
- * Warning will be printed if there is collision.
- */
- if (err && (err != -EEXIST))
- break;
- err = 0;
@@ -541,7 +522,7 @@ static void __remove_section(struct zone *zone, unsigned long pfn,
__remove_zone(zone, pfn, nr_pages);
- sparse_remove_one_section(ms, pfn, nr_pages, map_offset, altmap);
+ sparse_remove_section(ms, pfn, nr_pages, map_offset, altmap);