From ad820c5dd47dff9397ef1e94388bc6577983f68b Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Mon, 6 Mar 2006 15:42:58 -0800 Subject: [PATCH] [PATCH] smaps: shared fix The point of the smaps "shared" is to count the number of pages that are mapped by more than one process, according to Mauricio Lin. However, smaps uses page_count for this, so it will return a false positive for every page that is mapped by just that one process, which is also in pagecache or swapcache. There are false positive situations for anonymous pages not in swapcache as well: - page reclaim, migration - get_user_pages (eg. direct-io, ptrace) Use page_mapcount instead, to count the number of mappings to the page. Use vm_normal_page so that weird things like /dev/mem aren't counted either. Signed-off-by: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/task_mmu.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 35787f907f12..91b7c15ab373 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -204,7 +204,6 @@ static void smaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd, { pte_t *pte, ptent; spinlock_t *ptl; - unsigned long pfn; struct page *page; pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); @@ -214,12 +213,12 @@ static void smaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd, continue; mss->resident += PAGE_SIZE; - pfn = pte_pfn(ptent); - if (!pfn_valid(pfn)) + + page = vm_normal_page(vma, addr, ptent); + if (!page) continue; - page = pfn_to_page(pfn); - if (page_count(page) >= 2) { + if (page_mapcount(page) >= 2) { if (pte_dirty(ptent)) mss->shared_dirty += PAGE_SIZE; else -- 2.20.1