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>
This commit is contained in:
Dan Williams
Linus Torvalds
parent
7ea6216049
commit
ba72b4c8cf
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@ -348,7 +348,7 @@ extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
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extern bool is_memblock_offlined(struct memory_block *mem);
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extern int sparse_add_section(int nid, unsigned long pfn,
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unsigned long nr_pages, struct vmem_altmap *altmap);
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extern void sparse_remove_one_section(struct mem_section *ms,
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extern void sparse_remove_section(struct mem_section *ms,
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unsigned long pfn, unsigned long nr_pages,
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unsigned long map_offset, struct vmem_altmap *altmap);
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extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
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@ -252,18 +252,6 @@ void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
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}
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#endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
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static int __meminit __add_section(int nid, unsigned long pfn,
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unsigned long nr_pages, struct vmem_altmap *altmap)
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{
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int ret;
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if (pfn_valid(pfn))
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return -EEXIST;
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ret = sparse_add_section(nid, pfn, nr_pages, altmap);
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return ret < 0 ? ret : 0;
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}
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static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
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const char *reason)
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{
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@ -327,18 +315,11 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
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pfns = min(nr_pages, PAGES_PER_SECTION
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- (pfn & ~PAGE_SECTION_MASK));
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err = __add_section(nid, pfn, pfns, altmap);
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err = sparse_add_section(nid, pfn, pfns, altmap);
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if (err)
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break;
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pfn += pfns;
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nr_pages -= pfns;
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/*
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* EEXIST is finally dealt with by ioresource collision
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* check. see add_memory() => register_memory_resource()
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* Warning will be printed if there is collision.
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*/
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if (err && (err != -EEXIST))
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break;
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err = 0;
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cond_resched();
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}
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vmemmap_populate_print_last();
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@ -541,7 +522,7 @@ static void __remove_section(struct zone *zone, unsigned long pfn,
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return;
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__remove_zone(zone, pfn, nr_pages);
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sparse_remove_one_section(ms, pfn, nr_pages, map_offset, altmap);
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sparse_remove_section(ms, pfn, nr_pages, map_offset, altmap);
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}
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/**
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@ -5974,7 +5974,7 @@ void __ref memmap_init_zone_device(struct zone *zone,
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* pfn out of zone.
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*
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* Please note that MEMMAP_HOTPLUG path doesn't clear memmap
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* because this is done early in sparse_add_one_section
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* because this is done early in section_activate()
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*/
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if (!(pfn & (pageblock_nr_pages - 1))) {
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set_pageblock_migratetype(page, MIGRATE_MOVABLE);
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206
mm/sparse.c
206
mm/sparse.c
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@ -83,8 +83,15 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
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unsigned long root = SECTION_NR_TO_ROOT(section_nr);
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struct mem_section *section;
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/*
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* An existing section is possible in the sub-section hotplug
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* case. First hot-add instantiates, follow-on hot-add reuses
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* the existing section.
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*
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* The mem_hotplug_lock resolves the apparent race below.
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*/
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if (mem_section[root])
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return -EEXIST;
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return 0;
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section = sparse_index_alloc(nid);
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if (!section)
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@ -715,10 +722,120 @@ static void free_map_bootmem(struct page *memmap)
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}
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#endif /* CONFIG_SPARSEMEM_VMEMMAP */
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static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
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struct vmem_altmap *altmap)
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{
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DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
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DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
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struct mem_section *ms = __pfn_to_section(pfn);
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bool section_is_early = early_section(ms);
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struct page *memmap = NULL;
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unsigned long *subsection_map = ms->usage
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? &ms->usage->subsection_map[0] : NULL;
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subsection_mask_set(map, pfn, nr_pages);
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if (subsection_map)
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bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
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if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
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"section already deactivated (%#lx + %ld)\n",
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pfn, nr_pages))
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return;
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/*
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* There are 3 cases to handle across two configurations
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* (SPARSEMEM_VMEMMAP={y,n}):
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*
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* 1/ deactivation of a partial hot-added section (only possible
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* in the SPARSEMEM_VMEMMAP=y case).
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* a/ section was present at memory init
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* b/ section was hot-added post memory init
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* 2/ deactivation of a complete hot-added section
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* 3/ deactivation of a complete section from memory init
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*
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* For 1/, when subsection_map does not empty we will not be
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* freeing the usage map, but still need to free the vmemmap
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* range.
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*
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* For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified
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*/
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bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
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if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION)) {
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unsigned long section_nr = pfn_to_section_nr(pfn);
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if (!section_is_early) {
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kfree(ms->usage);
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ms->usage = NULL;
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}
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memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
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ms->section_mem_map = sparse_encode_mem_map(NULL, section_nr);
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}
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if (section_is_early && memmap)
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free_map_bootmem(memmap);
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else
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depopulate_section_memmap(pfn, nr_pages, altmap);
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}
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static struct page * __meminit section_activate(int nid, unsigned long pfn,
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unsigned long nr_pages, struct vmem_altmap *altmap)
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{
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DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
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struct mem_section *ms = __pfn_to_section(pfn);
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struct mem_section_usage *usage = NULL;
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unsigned long *subsection_map;
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struct page *memmap;
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int rc = 0;
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subsection_mask_set(map, pfn, nr_pages);
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if (!ms->usage) {
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usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
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if (!usage)
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return ERR_PTR(-ENOMEM);
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ms->usage = usage;
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}
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subsection_map = &ms->usage->subsection_map[0];
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if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
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rc = -EINVAL;
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else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
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rc = -EEXIST;
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else
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bitmap_or(subsection_map, map, subsection_map,
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SUBSECTIONS_PER_SECTION);
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if (rc) {
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if (usage)
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ms->usage = NULL;
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kfree(usage);
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return ERR_PTR(rc);
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}
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/*
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* The early init code does not consider partially populated
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* initial sections, it simply assumes that memory will never be
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* referenced. If we hot-add memory into such a section then we
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* do not need to populate the memmap and can simply reuse what
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* is already there.
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*/
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if (nr_pages < PAGES_PER_SECTION && early_section(ms))
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return pfn_to_page(pfn);
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memmap = populate_section_memmap(pfn, nr_pages, nid, altmap);
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if (!memmap) {
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section_deactivate(pfn, nr_pages, altmap);
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return ERR_PTR(-ENOMEM);
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}
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return memmap;
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}
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/**
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* sparse_add_one_section - add a memory section
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* sparse_add_section - add a memory section, or populate an existing one
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* @nid: The node to add section on
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* @start_pfn: start pfn of the memory range
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* @nr_pages: number of pfns to add in the section
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* @altmap: device page map
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*
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* This is only intended for hotplug.
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@ -732,51 +849,34 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn,
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unsigned long nr_pages, struct vmem_altmap *altmap)
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{
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unsigned long section_nr = pfn_to_section_nr(start_pfn);
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struct mem_section_usage *usage;
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struct mem_section *ms;
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struct page *memmap;
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int ret;
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/*
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* no locking for this, because it does its own
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* plus, it does a kmalloc
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*/
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ret = sparse_index_init(section_nr, nid);
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if (ret < 0 && ret != -EEXIST)
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if (ret < 0)
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return ret;
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ret = 0;
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memmap = populate_section_memmap(start_pfn, PAGES_PER_SECTION, nid,
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altmap);
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if (!memmap)
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return -ENOMEM;
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usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
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if (!usage) {
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depopulate_section_memmap(start_pfn, PAGES_PER_SECTION, altmap);
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return -ENOMEM;
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}
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ms = __pfn_to_section(start_pfn);
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if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
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ret = -EEXIST;
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goto out;
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}
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memmap = section_activate(nid, start_pfn, nr_pages, altmap);
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if (IS_ERR(memmap))
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return PTR_ERR(memmap);
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/*
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* Poison uninitialized struct pages in order to catch invalid flags
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* combinations.
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*/
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page_init_poison(memmap, sizeof(struct page) * PAGES_PER_SECTION);
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page_init_poison(pfn_to_page(start_pfn), sizeof(struct page) * nr_pages);
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ms = __pfn_to_section(start_pfn);
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set_section_nid(section_nr, nid);
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section_mark_present(ms);
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sparse_init_one_section(ms, section_nr, memmap, usage, 0);
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out:
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if (ret < 0) {
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kfree(usage);
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depopulate_section_memmap(start_pfn, PAGES_PER_SECTION, altmap);
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}
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return ret;
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/* Align memmap to section boundary in the subsection case */
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if (section_nr_to_pfn(section_nr) != start_pfn)
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memmap = pfn_to_kaddr(section_nr_to_pfn(section_nr));
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sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0);
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return 0;
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}
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#ifdef CONFIG_MEMORY_FAILURE
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@ -809,48 +909,12 @@ static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
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}
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#endif
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static void free_section_usage(struct mem_section *ms, struct page *memmap,
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struct mem_section_usage *usage, unsigned long pfn,
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unsigned long nr_pages, struct vmem_altmap *altmap)
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{
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if (!usage)
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return;
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/*
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* Check to see if allocation came from hot-plug-add
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*/
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if (!early_section(ms)) {
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kfree(usage);
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if (memmap)
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depopulate_section_memmap(pfn, nr_pages, altmap);
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return;
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}
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/*
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* The usemap came from bootmem. This is packed with other usemaps
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* on the section which has pgdat at boot time. Just keep it as is now.
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*/
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if (memmap)
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free_map_bootmem(memmap);
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}
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void sparse_remove_one_section(struct mem_section *ms, unsigned long pfn,
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void sparse_remove_section(struct mem_section *ms, unsigned long pfn,
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unsigned long nr_pages, unsigned long map_offset,
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struct vmem_altmap *altmap)
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{
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struct page *memmap = NULL;
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struct mem_section_usage *usage = NULL;
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if (ms->section_mem_map) {
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usage = ms->usage;
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memmap = sparse_decode_mem_map(ms->section_mem_map,
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__section_nr(ms));
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ms->section_mem_map = 0;
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ms->usage = NULL;
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}
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clear_hwpoisoned_pages(memmap + map_offset, nr_pages - map_offset);
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free_section_usage(ms, memmap, usage, pfn, nr_pages, altmap);
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clear_hwpoisoned_pages(pfn_to_page(pfn) + map_offset,
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nr_pages - map_offset);
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section_deactivate(pfn, nr_pages, altmap);
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}
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#endif /* CONFIG_MEMORY_HOTPLUG */
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