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author | Dan Williams <dan.j.williams@intel.com> | 2019-07-18 15:58:04 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-18 17:08:07 -0700 |
commit | f46edbd1b1516da1fb34c917775168d5df576f78 (patch) | |
tree | c65705ac536ff7532eff765c17ef61206d26db60 /include/linux/mmzone.h | |
parent | 326e1b8f83a4318b09033ef754f40c785aed5e68 (diff) | |
download | linux-f46edbd1b1516da1fb34c917775168d5df576f78.tar.gz linux-f46edbd1b1516da1fb34c917775168d5df576f78.tar.bz2 linux-f46edbd1b1516da1fb34c917775168d5df576f78.zip |
mm/sparsemem: add helpers track active portions of a section at boot
Prepare for hot{plug,remove} of sub-ranges of a section by tracking a
sub-section active bitmask, each bit representing a PMD_SIZE span of the
architecture's memory hotplug section size.
The implications of a partially populated section is that pfn_valid()
needs to go beyond a valid_section() check and either determine that the
section is an "early section", or read the sub-section active ranges
from the bitmask. The expectation is that the bitmask (subsection_map)
fits in the same cacheline as the valid_section() / early_section()
data, so the incremental performance overhead to pfn_valid() should be
negligible.
The rationale for using early_section() to short-ciruit the
subsection_map check is that there are legacy code paths that use
pfn_valid() at section granularity before validating the pfn against
pgdat data. So, the early_section() check allows those traditional
assumptions to persist while also permitting subsection_map to tell the
truth for purposes of populating the unused portions of early sections
with PMEM and other ZONE_DEVICE mappings.
Link: http://lkml.kernel.org/r/156092350874.979959.18185938451405518285.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Qian Cai <cai@lca.pw>
Tested-by: Jane Chu <jane.chu@oracle.com>
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: 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/linux/mmzone.h')
-rw-r--r-- | include/linux/mmzone.h | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 4be40634238b..7747ec9de588 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1178,6 +1178,8 @@ struct mem_section_usage { unsigned long pageblock_flags[0]; }; +void subsection_map_init(unsigned long pfn, unsigned long nr_pages); + struct page; struct page_ext; struct mem_section { @@ -1321,12 +1323,40 @@ static inline struct mem_section *__pfn_to_section(unsigned long pfn) extern unsigned long __highest_present_section_nr; +static inline int subsection_map_index(unsigned long pfn) +{ + return (pfn & ~(PAGE_SECTION_MASK)) / PAGES_PER_SUBSECTION; +} + +#ifdef CONFIG_SPARSEMEM_VMEMMAP +static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) +{ + int idx = subsection_map_index(pfn); + + return test_bit(idx, ms->usage->subsection_map); +} +#else +static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) +{ + return 1; +} +#endif + #ifndef CONFIG_HAVE_ARCH_PFN_VALID static inline int pfn_valid(unsigned long pfn) { + struct mem_section *ms; + if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) return 0; - return valid_section(__nr_to_section(pfn_to_section_nr(pfn))); + ms = __nr_to_section(pfn_to_section_nr(pfn)); + if (!valid_section(ms)) + return 0; + /* + * Traditionally early sections always returned pfn_valid() for + * the entire section-sized span. + */ + return early_section(ms) || pfn_section_valid(ms, pfn); } #endif @@ -1358,6 +1388,7 @@ void sparse_init(void); #define sparse_init() do {} while (0) #define sparse_index_init(_sec, _nid) do {} while (0) #define pfn_present pfn_valid +#define subsection_map_init(_pfn, _nr_pages) do {} while (0) #endif /* CONFIG_SPARSEMEM */ /* |