From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f176.google.com (mail-we0-f176.google.com [74.125.82.176]) by kanga.kvack.org (Postfix) with ESMTP id 7898A6B0105 for ; Tue, 10 Jun 2014 18:05:02 -0400 (EDT) Received: by mail-we0-f176.google.com with SMTP id u56so3622887wes.21 for ; Tue, 10 Jun 2014 15:05:01 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id a10si18895363wiz.51.2014.06.10.15.05.00 for ; Tue, 10 Jun 2014 15:05:01 -0700 (PDT) Date: Wed, 11 Jun 2014 00:04:51 +0200 From: Andrea Arcangeli Subject: Re: [PATCH, RFC 00/10] THP refcounting redesign Message-ID: <20140610220451.GG19660@redhat.com> References: <1402329861-7037-1-git-send-email-kirill.shutemov@linux.intel.com> <20140610204640.GA9594@node.dhcp.inet.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140610204640.GA9594@node.dhcp.inet.fi> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Christoph Lameter , "Kirill A. Shutemov" , Andrew Morton , Dave Hansen , Hugh Dickins , Mel Gorman , Rik van Riel , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Tue, Jun 10, 2014 at 11:46:40PM +0300, Kirill A. Shutemov wrote: > Agreed. The patchset drops tail page refcounting. Very possibly I misread something or a later patch fixes this up, I just did a basic code review, but from the new code of split_huge_page it looks like it returns -EBUSY after checking the individual tail page refcounts, so it's not clear how that defines as "dropped". + for (i = 0; i < HPAGE_PMD_NR; i++) + tail_count += page_mapcount(page + i); + if (tail_count != page_count(page) - 1) { + BUG_ON(tail_count > page_count(page) - 1); + compound_unlock(page); + spin_unlock_irq(&zone->lru_lock); + return -EBUSY; -- 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