From 144552ff8995dd34d049a203d636b259ab751137 Mon Sep 17 00:00:00 2001 From: Anthony Yznaga Date: Fri, 28 Dec 2018 00:37:31 -0800 Subject: /proc/kpagecount: return 0 for special pages that are never mapped Certain pages that are never mapped to userspace have a type indicated in the page_type field of their struct pages (e.g. PG_buddy). page_type overlaps with _mapcount so set the count to 0 and avoid calling page_mapcount() for these pages. [anthony.yznaga@oracle.com: incorporate feedback from Matthew Wilcox] Link: http://lkml.kernel.org/r/1544481313-27318-1-git-send-email-anthony.yznaga@oracle.com Link: http://lkml.kernel.org/r/1543963526-27917-1-git-send-email-anthony.yznaga@oracle.com Signed-off-by: Anthony Yznaga Reviewed-by: Andrew Morton Acked-by: Matthew Wilcox Reviewed-by: Naoya Horiguchi Cc: Vlastimil Babka Cc: David Rientjes Cc: Alexey Dobriyan Cc: Kirill A. Shutemov Cc: Mike Rapoport Cc: Michal Hocko Cc: Alexander Duyck Cc: Johannes Weiner Cc: Miles Chen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/page.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/proc/page.c b/fs/proc/page.c index 6c517b11acf8..40b05e0d4274 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -46,7 +46,7 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf, ppage = pfn_to_page(pfn); else ppage = NULL; - if (!ppage || PageSlab(ppage)) + if (!ppage || PageSlab(ppage) || page_has_type(ppage)) pcount = 0; else pcount = page_mapcount(ppage); -- cgit v1.2.3-70-g09d2