Commit 9996f05e authored Oct 07, 2016 by Kirill A. Shutemov Committed by Linus Torvalds Oct 07, 2016

mm: clarify why we avoid page_mapcount() for slab pages in dump_page()

Let's add comment on why we skip page_mapcount() for sl[aou]b pages.

Link: http://lkml.kernel.org/r/20160922105532.GB24593@node


Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 8f26e0b1

mm/debug.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -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",