X-Git-Url: http://git.cascardo.info/?a=blobdiff_plain;f=mm%2Fdebug.c;h=9feb699c5d257795ebf26533732a2578b826a6a6;hb=9099daed9c6991a512c1f74b92ec49daf9408cda;hp=74c7cae4f6837dcb5a599df800e7300ff851519c;hpb=e55f1d1d13e7f1c364672d667d78fd1f640ab9f9;p=cascardo%2Flinux.git

diff --git a/mm/debug.c b/mm/debug.c
index 74c7cae4f683..9feb699c5d25 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -42,6 +42,11 @@ const struct trace_print_flags vmaflag_names[] = {
 
 void __dump_page(struct page *page, const char *reason)
 {
+	/*
+	 * Avoid VM_BUG_ON() in page_mapcount().
+	 * page->_mapcount space in struct page is used by sl[aou]b pages to
+	 * encode own info.
+	 */
 	int mapcount = PageSlab(page) ? 0 : page_mapcount(page);
 
 	pr_emerg("page:%p count:%d mapcount:%d mapping:%p index:%#lx",