The patch titled
Subject: mm/sparsemem: introduce a SECTION_IS_EARLY flag
has been added to the -mm tree. Its filename is
mm-sparsemem-introduce-a-section_is_early-flag.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-sparsemem-introduce-a-section_is_early-flag.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-sparsemem-introduce-a-section_is_early-flag.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: mm/sparsemem: introduce a SECTION_IS_EARLY flag
In preparation for sub-section hotplug, track whether a given section was
created during early memory initialization, or later via memory hotplug.
This distinction is needed to maintain the coarse expectation that
pfn_valid() returns true for any pfn within a given section even if that
section has pages that are reserved from the page allocator.
For example one of the of goals of subsection hotplug is to support cases
where the system physical memory layout collides System RAM and PMEM
within a section. Several pfn_valid() users expect to just check if a
section is valid, but they are not careful to check if the given pfn is
within a "System RAM" boundary and instead expect pgdat information to
further validate the pfn.
Rather than unwind those paths to make their pfn_valid() queries more
precise a follow on patch uses the SECTION_IS_EARLY flag to maintain the
traditional expectation that pfn_valid() returns true for all early
sections.
Link: https://lore.kernel.org/lkml/1560366952-10660-1-git-send-email-cai@xxxxxx/
Link: http://lkml.kernel.org/r/156092350358.979959.5817209875548072819.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Reported-by: Qian Cai <cai@xxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Jane Chu <jane.chu@xxxxxxxxxx>
Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 8 +++++++-
mm/sparse.c | 20 +++++++++-----------
2 files changed, 16 insertions(+), 12 deletions(-)
--- a/include/linux/mmzone.h~mm-sparsemem-introduce-a-section_is_early-flag
+++ a/include/linux/mmzone.h
@@ -1261,7 +1261,8 @@ extern size_t mem_section_usage_size(voi
#define SECTION_MARKED_PRESENT (1UL<<0)
#define SECTION_HAS_MEM_MAP (1UL<<1)
#define SECTION_IS_ONLINE (1UL<<2)
-#define SECTION_MAP_LAST_BIT (1UL<<3)
+#define SECTION_IS_EARLY (1UL<<3)
+#define SECTION_MAP_LAST_BIT (1UL<<4)
#define SECTION_MAP_MASK (~(SECTION_MAP_LAST_BIT-1))
#define SECTION_NID_SHIFT 3
@@ -1287,6 +1288,11 @@ static inline int valid_section(struct m
return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
}
+static inline int early_section(struct mem_section *section)
+{
+ return (section && (section->section_mem_map & SECTION_IS_EARLY));
+}
+
static inline int valid_section_nr(unsigned long nr)
{
return valid_section(__nr_to_section(nr));
--- a/mm/sparse.c~mm-sparsemem-introduce-a-section_is_early-flag
+++ a/mm/sparse.c
@@ -288,11 +288,11 @@ struct page *sparse_decode_mem_map(unsig
static void __meminit sparse_init_one_section(struct mem_section *ms,
unsigned long pnum, struct page *mem_map,
- struct mem_section_usage *usage)
+ struct mem_section_usage *usage, unsigned long flags)
{
ms->section_mem_map &= ~SECTION_MAP_MASK;
- ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
- SECTION_HAS_MEM_MAP;
+ ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
+ | SECTION_HAS_MEM_MAP | flags;
ms->usage = usage;
}
@@ -497,7 +497,8 @@ static void __init sparse_init_nid(int n
goto failed;
}
check_usemap_section_nr(nid, usage);
- sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage);
+ sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
+ SECTION_IS_EARLY);
usage = (void *) usage + mem_section_usage_size();
}
sparse_buffer_fini();
@@ -732,7 +733,7 @@ int __meminit sparse_add_one_section(int
set_section_nid(section_nr, nid);
section_mark_present(ms);
- sparse_init_one_section(ms, section_nr, memmap, usage);
+ sparse_init_one_section(ms, section_nr, memmap, usage, 0);
out:
if (ret < 0) {
@@ -772,19 +773,16 @@ static inline void clear_hwpoisoned_page
}
#endif
-static void free_section_usage(struct page *memmap,
+static void free_section_usage(struct mem_section *ms, struct page *memmap,
struct mem_section_usage *usage, struct vmem_altmap *altmap)
{
- struct page *usage_page;
-
if (!usage)
return;
- usage_page = virt_to_page(usage);
/*
* Check to see if allocation came from hot-plug-add
*/
- if (PageSlab(usage_page) || PageCompound(usage_page)) {
+ if (!early_section(ms)) {
kfree(usage);
if (memmap)
__kfree_section_memmap(memmap, altmap);
@@ -816,6 +814,6 @@ void sparse_remove_one_section(struct me
clear_hwpoisoned_pages(memmap + map_offset,
PAGES_PER_SECTION - map_offset);
- free_section_usage(memmap, usage, altmap);
+ free_section_usage(ms, memmap, usage, altmap);
}
#endif /* CONFIG_MEMORY_HOTPLUG */
_
Patches currently in -mm which might be from dan.j.williams@xxxxxxxxx are
mm-sparsemem-introduce-struct-mem_section_usage.patch
mm-sparsemem-introduce-a-section_is_early-flag.patch
mm-sparsemem-add-helpers-track-active-portions-of-a-section-at-boot.patch
mm-hotplug-prepare-shrink_zone-pgdat_span-for-sub-section-removal.patch
mm-sparsemem-convert-kmalloc_section_memmap-to-populate_section_memmap.patch
mm-hotplug-kill-is_dev_zone-usage-in-__remove_pages.patch
mm-kill-is_dev_zone-helper.patch
mm-sparsemem-prepare-for-sub-section-ranges.patch
mm-sparsemem-support-sub-section-hotplug.patch
mm-document-zone_device-memory-model-implications.patch
mm-devm_memremap_pages-enable-sub-section-remap.patch
libnvdimm-pfn-fix-fsdax-mode-namespace-info-block-zero-fields.patch
libnvdimm-pfn-stop-padding-pmem-namespaces-to-section-alignment.patch
