From b676b293fb48672904ee1b9828cb50b4eed01717 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 8 Oct 2012 16:34:03 -0700 Subject: mm, thp: fix mapped pages avoiding unevictable list on mlock When a transparent hugepage is mapped and it is included in an mlock() range, follow_page() incorrectly avoids setting the page's mlock bit and moving it to the unevictable lru. This is evident if you try to mlock(), munlock(), and then mlock() a range again. Currently: #define MAP_SIZE (4 << 30) /* 4GB */ void *ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0); mlock(ptr, MAP_SIZE); $ grep -E "Unevictable|Inactive\(anon" /proc/meminfo Inactive(anon): 6304 kB Unevictable: 4213924 kB munlock(ptr, MAP_SIZE); Inactive(anon): 4186252 kB Unevictable: 19652 kB mlock(ptr, MAP_SIZE); Inactive(anon): 4198556 kB Unevictable: 21684 kB Notice that less than 2MB was added to the unevictable list; this is because these pages in the range are not transparent hugepages since the 4GB range was allocated with mmap() and has no specific alignment. If posix_memalign() were used instead, unevictable would not have grown at all on the second mlock(). The fix is to call mlock_vma_page() so that the mlock bit is set and the page is added to the unevictable list. With this patch: mlock(ptr, MAP_SIZE); Inactive(anon): 4056 kB Unevictable: 4213940 kB munlock(ptr, MAP_SIZE); Inactive(anon): 4198268 kB Unevictable: 19636 kB mlock(ptr, MAP_SIZE); Inactive(anon): 4008 kB Unevictable: 4213940 kB Signed-off-by: David Rientjes Acked-by: Hugh Dickins Reviewed-by: Andrea Arcangeli Cc: Naoya Horiguchi Cc: KAMEZAWA Hiroyuki Cc: Johannes Weiner Cc: Michel Lespinasse Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index 45bb6d296b6..fb135ba4aba 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1528,7 +1528,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, spin_unlock(&mm->page_table_lock); wait_split_huge_page(vma->anon_vma, pmd); } else { - page = follow_trans_huge_pmd(mm, address, + page = follow_trans_huge_pmd(vma, address, pmd, flags); spin_unlock(&mm->page_table_lock); goto out; -- cgit v1.2.3-18-g5258