From: Nick Piggin Date: Mon, 6 Mar 2006 23:42:58 +0000 (-0800) Subject: [PATCH] smaps: shared fix X-Git-Tag: v2.6.16-rc6~90 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ad820c5dd47dff9397ef1e94388bc6577983f68b;p=linux-2.6 [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 --- diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 35787f907f..91b7c15ab3 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