From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx197.postini.com [74.125.245.197]) by kanga.kvack.org (Postfix) with SMTP id B0F126B0096 for ; Mon, 12 Nov 2012 11:43:00 -0500 (EST) Received: by mail-wi0-f179.google.com with SMTP id hm6so2005558wib.8 for ; Mon, 12 Nov 2012 08:42:59 -0800 (PST) From: Michal Nazarewicz 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> References: <1352718446-32313-1-git-send-email-m.szyprowski@samsung.com> Date: Mon, 12 Nov 2012 17:42:50 +0100 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="=-=-=" Sender: owner-linux-mm@kvack.org List-ID: To: Marek Szyprowski , linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Cc: Kyungmin Park , Andrew Morton , Mel Gorman , Minchan Kim , Bartlomiej Zolnierkiewicz --=-=-= 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, 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