Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753128Ab2KLQnD (ORCPT ); Mon, 12 Nov 2012 11:43:03 -0500 Received: from mail-wg0-f42.google.com ([74.125.82.42]:50298 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751292Ab2KLQnA (ORCPT ); Mon, 12 Nov 2012 11:43:00 -0500 From: Michal Nazarewicz To: Marek Szyprowski , linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Cc: Marek Szyprowski , Kyungmin Park , Andrew Morton , Mel Gorman , Minchan Kim , Bartlomiej Zolnierkiewicz Subject: Re: [PATCH] mm: cma: WARN if freed memory is still in use In-Reply-To: <1352718446-32313-1-git-send-email-m.szyprowski@samsung.com> Organization: http://mina86.com/ References: <1352718446-32313-1-git-send-email-m.szyprowski@samsung.com> User-Agent: Notmuch/ (http://notmuchmail.org) Emacs/24.2.50.1 (x86_64-unknown-linux-gnu) X-Face: PbkBB1w#)bOqd`iCe"Ds{e+!C7`pkC9a|f)Qo^BMQvy\q5x3?vDQJeN(DS?|-^$uMti[3D*#^_Ts"pU$jBQLq~Ud6iNwAw_r_o_4]|JO?]}P_}Nc&"p#D(ZgUb4uCNPe7~a[DbPG0T~!&c.y$Ur,=N4RT>]dNpd;KFrfMCylc}gc??'U2j,!8%xdD Face: 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 X-PGP: 50751FF4 X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 Date: Mon, 12 Nov 2012 17:42:50 +0100 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="=-=-=" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2719 Lines: 81 --=-=-= Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Mon, Nov 12 2012, Marek Szyprowski wrote: > Memory return to free_contig_range() must have no other references. Let > kernel to complain loudly if page reference count is not equal to 1. > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 022e4ed..290c2eb 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5888,8 +5888,13 @@ done: >=20=20 > void free_contig_range(unsigned long pfn, unsigned nr_pages) > { > - for (; nr_pages--; ++pfn) > - __free_page(pfn_to_page(pfn)); > + struct page *page =3D pfn_to_page(pfn); > + int refcount =3D nr_pages; > + for (; nr_pages--; page++) { > + refcount -=3D page_count(page) =3D=3D 1; > + __free_page(page); > + } > + WARN(refcount !=3D 0, "some pages are still in use!\n"); This decrementing logic seem backward to me. Why not: struct page *page =3D pfn_to_page(pfn); unsigned int refcount =3D 0; for (; nr_pages--; page++) { refcount +=3D page_count(page) !=3D 1; __free_page(page); } WARN(refcount !=3D 0, "some pages are still in use!\n"); > } > #endif --=20 Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=3D./ `o ..o | Computer Science, Micha=C5=82 =E2=80=9Cmina86=E2=80=9D Nazarewicz = (o o) ooo +------------------ooO--(_)--Ooo-- --=-=-= Content-Type: multipart/signed; boundary="==-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" --==-=-= Content-Type: text/plain --==-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJQoScKAAoJECBgQBJQdR/0sNQQAIxdNyaczFaJA055aFVoZCoG 6w4IxqtMZeD96Vk0XD1msOH8wzmBknWEsknqKcRVEIp1Q05stiVlpn3Ny+1sUl6i SjdUcVcyGJESvtQEA+af5M/PnOxXLj7kuFUGZ/knTOgN79V7cnR/3NvGpP8IBBJ4 xZeI/+PgxKXRIB07UqNeLnX6bQrwubxPPTOAZa9WzqajrtcT9RBD5qQRT4wzxzGb +5MCVCa0GhhIfOXr7qsdMETIA+kJXycm9SMfVmJw3yoNt+GwLDKltQBRWMzH8xkN 404/qPkikDuNBdSRVRPhohQQ0JaOGOVk6r1pfGS8EDjEjGX0T8/r/OvihChdZ5fI yxi0pMY9qBX2ExVkIwzbQ7no/vpFs1e/OmvpU4TCA/sBvxSAqn6n4slhJKAzHJai emW78Y/j+obR5q8VdQaYPMgmI8ZW8y9GhhGIh8/COa6/wu+Gw2PJLTHLjRYQKe5D 90bTDChvuLc0ZNw0dTZ0GTvmMHqiGmpQnh/gMJAOuIYKHgyBWuDmqisnq+/M3HDz MVIozN8sWLNn0+nbVt+CjfroQC42rcKhUP9AOwBqyUfC6o1gFFR4EBJFj7FLP/fM zR15WXlKy5gkLLEAeLNca6Uy7ihoPTSn4Evhcpw7qYNVB2WjdsqQNyUrP7RmsPVy LU7Y37q/6j/xF1gDrWgF =4w/2 -----END PGP SIGNATURE----- --==-=-=-- --=-=-=-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/