From ca79b0c211af63fa3276f0e3fd7dd9ada2439839 Mon Sep 17 00:00:00 2001 From: Arun KS Date: Fri, 28 Dec 2018 00:34:29 -0800 Subject: mm: convert totalram_pages and totalhigh_pages variables to atomic totalram_pages and totalhigh_pages are made static inline function. Main motivation was that managed_page_count_lock handling was complicating things. It was discussed in length here, https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes better to remove the lock and convert variables to atomic, with preventing poteintial store-to-read tearing as a bonus. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org Signed-off-by: Arun KS Suggested-by: Michal Hocko Suggested-by: Vlastimil Babka Reviewed-by: Konstantin Khlebnikov Reviewed-by: Pavel Tatashin Acked-by: Michal Hocko Acked-by: Vlastimil Babka Cc: David Hildenbrand Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4b5c4ff68f18..eb2027892ef9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -16,6 +16,7 @@ #include #include +#include #include #include #include @@ -124,7 +125,8 @@ EXPORT_SYMBOL(node_states); /* Protect totalram_pages and zone->managed_pages */ static DEFINE_SPINLOCK(managed_page_count_lock); -unsigned long totalram_pages __read_mostly; +atomic_long_t _totalram_pages __read_mostly; +EXPORT_SYMBOL(_totalram_pages); unsigned long totalreserve_pages __read_mostly; unsigned long totalcma_pages __read_mostly; @@ -4747,11 +4749,11 @@ EXPORT_SYMBOL_GPL(si_mem_available); void si_meminfo(struct sysinfo *val) { - val->totalram = totalram_pages; + val->totalram = totalram_pages(); val->sharedram = global_node_page_state(NR_SHMEM); val->freeram = global_zone_page_state(NR_FREE_PAGES); val->bufferram = nr_blockdev_pages(); - val->totalhigh = totalhigh_pages; + val->totalhigh = totalhigh_pages(); val->freehigh = nr_free_highpages(); val->mem_unit = PAGE_SIZE; } @@ -7077,10 +7079,10 @@ void adjust_managed_page_count(struct page *page, long count) { spin_lock(&managed_page_count_lock); atomic_long_add(count, &page_zone(page)->managed_pages); - totalram_pages += count; + totalram_pages_add(count); #ifdef CONFIG_HIGHMEM if (PageHighMem(page)) - totalhigh_pages += count; + totalhigh_pages_add(count); #endif spin_unlock(&managed_page_count_lock); } @@ -7123,9 +7125,9 @@ EXPORT_SYMBOL(free_reserved_area); void free_highmem_page(struct page *page) { __free_reserved_page(page); - totalram_pages++; + totalram_pages_inc(); atomic_long_inc(&page_zone(page)->managed_pages); - totalhigh_pages++; + totalhigh_pages_inc(); } #endif @@ -7174,10 +7176,10 @@ void __init mem_init_print_info(const char *str) physpages << (PAGE_SHIFT - 10), codesize >> 10, datasize >> 10, rosize >> 10, (init_data_size + init_code_size) >> 10, bss_size >> 10, - (physpages - totalram_pages - totalcma_pages) << (PAGE_SHIFT - 10), + (physpages - totalram_pages() - totalcma_pages) << (PAGE_SHIFT - 10), totalcma_pages << (PAGE_SHIFT - 10), #ifdef CONFIG_HIGHMEM - totalhigh_pages << (PAGE_SHIFT - 10), + totalhigh_pages() << (PAGE_SHIFT - 10), #endif str ? ", " : "", str ? str : ""); } -- cgit v1.2.3