On Thu, Feb 04, 2016 at 04:08:01PM +0900, Naoya Horiguchi wrote: > Currently /proc/kpageflags returns nothing for "tail" buddy pages, which > is inconvenient when grasping how free pages are distributed. This patch > sets KPF_BUDDY for such pages.
Looks reasonable to me, Reviewed-by: Vladimir Davydov <[email protected]> > > With this patch: > > $ grep MemFree /proc/meminfo ; tools/vm/page-types -b buddy > MemFree: 3134992 kB > flags page-count MB symbolic-flags > long-symbolic-flags > 0x0000000000000400 779272 3044 > __________B_______________________________ buddy > 0x0000000000000c00 4385 17 > __________BM______________________________ buddy,mmap > total 783657 3061 Why are buddy pages reported as mmapped? That looks weird. Shouldn't we fix it? Something like this, may be? -- From: Vladimir Davydov <[email protected]> Subject: [PATCH] proc: kpageflags: do not report buddy and balloon pages as mapped PageBuddy and PageBalloon are not usual page flags - they are identified by a special negative (so as not to confuse with mapped pages) value of page->_mapcount. Since /proc/kpageflags uses page_mapcount helper to check if a page is mapped, it reports pages of these kinds as being mapped, which is confusing. Fix that by replacing page_mapcount with page_mapped. Signed-off-by: Vladimir Davydov <[email protected]> diff --git a/fs/proc/page.c b/fs/proc/page.c index b2855eea5405..332450d87ea4 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -105,7 +105,7 @@ u64 stable_page_flags(struct page *page) * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the * simple test in page_mapcount() is not enough. */ - if (!PageSlab(page) && page_mapcount(page)) + if (!PageSlab(page) && page_mapped(page)) u |= 1 << KPF_MMAP; if (PageAnon(page)) u |= 1 << KPF_ANON;
