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/huge_memory.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'mm/huge_memory.c') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 08a943b9cf95..3a8d6b7d95db 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -971,11 +971,12 @@ out_unlock: return ret; } -struct page *follow_trans_huge_pmd(struct mm_struct *mm, +struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, unsigned int flags) { + struct mm_struct *mm = vma->vm_mm; struct page *page = NULL; assert_spin_locked(&mm->page_table_lock); @@ -998,6 +999,14 @@ struct page *follow_trans_huge_pmd(struct mm_struct *mm, _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd); } + if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { + if (page->mapping && trylock_page(page)) { + lru_add_drain(); + if (page->mapping) + mlock_vma_page(page); + unlock_page(page); + } + } page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; VM_BUG_ON(!PageCompound(page)); if (flags & FOLL_GET) -- cgit v1.2.3