From: Baoquan He <bhe@xxxxxxxxxx> Subject: mm/sparse.c: introduce a new function clear_subsection_map() Factor out the code which clear subsection map of one memory region from section_deactivate() into clear_subsection_map(). And also add helper function is_subsection_map_empty() to check if the current subsection map is empty or not. Link: http://lkml.kernel.org/r/20200312124414.439-3-bhe@xxxxxxxxxx Signed-off-by: Baoquan He <bhe@xxxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Acked-by: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Wei Yang <richard.weiyang@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/sparse.c | 31 +++++++++++++++++++++++-------- 1 file changed, 23 insertions(+), 8 deletions(-) --- a/mm/sparse.c~mm-sparsec-introduce-a-new-function-clear_subsection_map +++ a/mm/sparse.c @@ -705,15 +705,11 @@ static void free_map_bootmem(struct page } #endif /* CONFIG_SPARSEMEM_VMEMMAP */ -static void section_deactivate(unsigned long pfn, unsigned long nr_pages, - struct vmem_altmap *altmap) +static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages) { DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 }; DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 }; struct mem_section *ms = __pfn_to_section(pfn); - bool section_is_early = early_section(ms); - struct page *memmap = NULL; - bool empty; unsigned long *subsection_map = ms->usage ? &ms->usage->subsection_map[0] : NULL; @@ -724,8 +720,28 @@ static void section_deactivate(unsigned if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION), "section already deactivated (%#lx + %ld)\n", pfn, nr_pages)) - return; + return -EINVAL; + + bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION); + return 0; +} + +static bool is_subsection_map_empty(struct mem_section *ms) +{ + return bitmap_empty(&ms->usage->subsection_map[0], + SUBSECTIONS_PER_SECTION); +} +static void section_deactivate(unsigned long pfn, unsigned long nr_pages, + struct vmem_altmap *altmap) +{ + struct mem_section *ms = __pfn_to_section(pfn); + bool section_is_early = early_section(ms); + struct page *memmap = NULL; + bool empty; + + if (clear_subsection_map(pfn, nr_pages)) + return; /* * There are 3 cases to handle across two configurations * (SPARSEMEM_VMEMMAP={y,n}): @@ -743,8 +759,7 @@ static void section_deactivate(unsigned * * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified */ - bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION); - empty = bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION); + empty = is_subsection_map_empty(ms); if (empty) { unsigned long section_nr = pfn_to_section_nr(pfn); _
