From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id B38926B0071 for ; Mon, 1 Feb 2010 16:47:30 -0500 (EST) Date: Mon, 1 Feb 2010 15:46:47 -0600 (CST) From: Christoph Lameter Subject: Re: [PATCH 28 of 32] pmd_trans_huge migrate bugcheck In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: linux-mm@kvack.org, Marcelo Tosatti , Adam Litke , Avi Kivity , Izik Eidus , Hugh Dickins , Nick Piggin , Rik van Riel , Mel Gorman , Dave Hansen , Benjamin Herrenschmidt , Ingo Molnar , Mike Travis , KAMEZAWA Hiroyuki , Chris Wright , Andrew Morton , bpicco@redhat.com, KOSAKI Motohiro , Balbir Singh , Arnd Bergmann List-ID: On Sun, 31 Jan 2010, Andrea Arcangeli wrote: > diff --git a/mm/migrate.c b/mm/migrate.c > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -819,6 +820,10 @@ static int do_move_page_to_node_array(st > if (PageReserved(page) || PageKsm(page)) > goto put_and_set; > > + if (unlikely(PageTransCompound(page))) > + if (unlikely(split_huge_page(page))) > + goto put_and_set; > + > pp->page = page; > err = page_to_nid(page); How does this work? do_move_page_to_node_array takes an array of page pointers in pp (struct page_to_node). Lets say one is a compound page. Now we split this into 512 4k pages? and pp only points to the first of them? The rest of the move_pages() logic will only see one 4k page and move it. The remaining 511 pages are left dangling? With an increased refcount? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org