When moving a program from mmap'ing small pages to mmap'ing huge pages, a remarkable drop in rss ensues. For some reason hugepages were never accounted for in rss, which in my book is a clear bug. Sadly this bug has been present in hugetlbfs since it was merged back in 2002. There is every chance existing programs depend on hugepages not being counted as rss. I think the correct solution is to fix the bug and wait for someone to complain. It is just as likely that noone cares - as evidenced by the fact that noone seems to have noticed for ten years. Signed-off-by: Joern Engel <joern@xxxxxxxxx> --- mm/hugetlb.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 1a12f5b..705036c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1174,6 +1174,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, set_page_private(page, (unsigned long)spool); vma_commit_reservation(h, vma, addr); + add_mm_counter(vma->vm_mm, MM_ANONPAGES, pages_per_huge_page(h)); return page; } @@ -2406,6 +2407,9 @@ again: if (pte_dirty(pte)) set_page_dirty(page); + /* -pages_per_huge_page(h) wouldn't get sign-extended */ + add_mm_counter(vma->vm_mm, MM_ANONPAGES, -1 << h->order); + page_remove_rmap(page); force_flush = !__tlb_remove_page(tlb, page); if (force_flush) -- 1.7.10.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>