From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753085AbcBBWvD (ORCPT ); Tue, 2 Feb 2016 17:51:03 -0500 Received: from mail-wm0-f48.google.com ([74.125.82.48]:34660 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751158AbcBBWvB (ORCPT ); Tue, 2 Feb 2016 17:51:01 -0500 Date: Wed, 3 Feb 2016 00:50:58 +0200 From: "Kirill A. Shutemov" To: Mike Kravetz Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" , "Aneesh Kumar K.V" , Jerome Marchand , Naoya Horiguchi , Andrew Morton , Michal Hocko Subject: Re: [PATCH] mm/hugetlb: fix gigantic page initialization/allocation Message-ID: <20160202225058.GA8309@node.shutemov.name> References: <1454452420-25007-1-git-send-email-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1454452420-25007-1-git-send-email-mike.kravetz@oracle.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 02, 2016 at 02:33:40PM -0800, Mike Kravetz wrote: > Attempting to preallocate 1G gigantic huge pages at boot time with > "hugepagesz=1G hugepages=1" on the kernel command line will prevent > booting with the following: > > kernel BUG at mm/hugetlb.c:1218! > > When mapcount accounting was reworked, the setting of compound_mapcount_ptr > in prep_compound_gigantic_page was overlooked. As a result, the validation > of mapcount in free_huge_page fails. Oops. Soory for that. > > The "BUG_ON" checks in free_huge_page were also changed to "VM_BUG_ON_PAGE" > to assist with debugging. > > Fixes: af5642a8af ("mm: rework mapcount accounting to enable 4k mapping of THPs") > Suggested-by: Naoya Horiguchi > Signed-off-by: Mike Kravetz Acked-by: Kirill A. Shutemov > --- > mm/hugetlb.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 12908dc..d7a8024 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1214,8 +1214,8 @@ void free_huge_page(struct page *page) > > set_page_private(page, 0); > page->mapping = NULL; > - BUG_ON(page_count(page)); > - BUG_ON(page_mapcount(page)); > + VM_BUG_ON_PAGE(page_count(page), page); > + VM_BUG_ON_PAGE(page_mapcount(page), page); > restore_reserve = PagePrivate(page); > ClearPagePrivate(page); > > @@ -1286,6 +1286,7 @@ static void prep_compound_gigantic_page(struct page *page, unsigned int order) > set_page_count(p, 0); > set_compound_head(p, page); > } > + atomic_set(compound_mapcount_ptr(page), -1); > } > > /* > -- > 2.4.3 > > -- > 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 -- Kirill A. Shutemov