From 326e1b8f83a4318b09033ef754f40c785aed5e68 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 18 Jul 2019 15:58:00 -0700 Subject: [PATCH] mm/sparsemem: introduce a SECTION_IS_EARLY flag MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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@lca.pw/ Link: http://lkml.kernel.org/r/156092350358.979959.5817209875548072819.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reported-by: Qian Cai Tested-by: Aneesh Kumar K.V [ppc64] Reviewed-by: Oscar Salvador Cc: Michal Hocko Cc: Logan Gunthorpe Cc: David Hildenbrand Cc: Pavel Tatashin Cc: Jane Chu Cc: Jeff Moyer Cc: Jérôme Glisse Cc: Jonathan Corbet Cc: Mike Rapoport Cc: Toshi Kani Cc: Vlastimil Babka Cc: Wei Yang Cc: Jason Gunthorpe Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 8 +++++++- mm/sparse.c | 20 +++++++++----------- 2 files changed, 16 insertions(+), 12 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 2520336bdfd1..4be40634238b 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1260,7 +1260,8 @@ extern size_t mem_section_usage_size(void); #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 @@ -1286,6 +1287,11 @@ static inline int valid_section(struct mem_section *section) 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)); diff --git a/mm/sparse.c b/mm/sparse.c index 41bef8e1f65c..6d23a526279a 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -288,11 +288,11 @@ struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pn 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 nid, unsigned long pnum_begin, 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 nid, unsigned long start_pfn, 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_pages(struct page *memmap, int nr_pages) } #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 mem_section *ms, unsigned long map_offset, 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 */