From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753689Ab2GPRlH (ORCPT ); Mon, 16 Jul 2012 13:41:07 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:61707 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753214Ab2GPRlD (ORCPT ); Mon, 16 Jul 2012 13:41:03 -0400 From: Michal Nazarewicz To: Joonsoo Kim Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Marek Szyprowski , Minchan Kim , Christoph Lameter Subject: Re: [PATCH 3/3] mm: fix return value in __alloc_contig_migrate_range() References: <1342455272-32703-1-git-send-email-js1304@gmail.com> <1342455272-32703-3-git-send-email-js1304@gmail.com> 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-Url: http://mina86.com/ X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 X-PGP: 50751FF4 Date: Mon, 16 Jul 2012 19:40:56 +0200 In-Reply-To: <1342455272-32703-3-git-send-email-js1304@gmail.com> (Joonsoo Kim's message of "Tue, 17 Jul 2012 01:14:32 +0900") Message-ID: <871ukbr4d3.fsf@erwin.mina86.com> User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/24.0 (Slckware Linux) MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Transfer-Encoding: quoted-printable Joonsoo Kim writes: > migrate_pages() would return positive value in some failure case, > so 'ret > 0 ? 0 : ret' may be wrong. > This fix it and remove one dead statement. > > Signed-off-by: Joonsoo Kim > Cc: Michal Nazarewicz > Cc: Marek Szyprowski > Cc: Minchan Kim > Cc: Christoph Lameter Have you actually encountered this problem? If migrate_pages() fails with a positive value, the code that you are removing kicks in and =2DEBUSY is assigned to ret (now that I look at it, I think that in the current code the "return ret > 0 ? 0 : ret;" statement could be reduced to "return ret;"). Your code seems to be cleaner, but the commit message does not look accurate to me. > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 4403009..02d4519 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5673,7 +5673,6 @@ static int __alloc_contig_migrate_range(unsigned lo= ng start, unsigned long end) > } > tries =3D 0; > } else if (++tries =3D=3D 5) { > - ret =3D ret < 0 ? ret : -EBUSY; > break; > } >=20=20 > @@ -5683,7 +5682,7 @@ static int __alloc_contig_migrate_range(unsigned lo= ng start, unsigned long end) > } >=20=20 > putback_lru_pages(&cc.migratepages); > - return ret > 0 ? 0 : ret; > + return ret <=3D 0 ? ret : -EBUSY; > } >=20=20 > /* =2D-=20 Best regards, _ _ .o. | Liege of Serenly Enlightened Majesty of o' \,=3D./ `o ..o | Computer Science, Michal "mina86" Nazarewicz (o o) ooo +----ooO--(_)--Ooo-- --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJQBFIpAAoJECBgQBJQdR/0Gn4P/0pr6sIB9P2fneQiC+7zj495 09WOd/w9J0HPOg9wAjtXD6+NEDGUq6GywUUXWddB1g6yBbJsvHl+CL4tFkgoCO3Y p/hwVAh/ouQA+Yhnqnv7E8UnAWgRjQlEB02p3DbNPwJ1kqtz/OhMDm0jNKOSL6rj TkSYPDtgHABo5UXPrC2LRl5JDfM3Xwnavfxs6c8Ze0hgddsJ/tr2NHRgELy4mS6X 9gj4e7W65L8KBPj2kACI54dm2vbKBZXbqKeJn0rfUCUHDvt7tWDrtXb58uvsNQTS whfp+TO5ysmk/zf4ENlokijQFs24rvTVk22vV4Joyu2NaelhGvsZ8GOjURyaDp0R hmBepZDFrGWe5nTu1e3iHIBpyd3CPQ+a2gIxUOZqBEX49+/6qs6WRgOYBeuLIJGB vveb+Tf52ph7Lx+EPuNHBSnY7dd5Ux+n64znL6wHK4Y8Qf2QMovhZcsq4ERY2xy7 3/KKiXCsKYKihrjIRtcKbYUS33NoGWLCu1+76+kD9zoYFpCHJyT9YmoSwwGAYHx1 A4BSKLiOYVASQWU+nuCunlDJDvzA+J4lsPO7mLXbqT8aeGkZpWmTdXWI+8jCJYDu Q6mKpzk5uf4mAdAtCd066j9rCYDSKHGYpaAtRlDwF/BxbiPu5r2uy2kUafqWgZDS xpyxqIZhkty7uZr2ZLxW =gy2Q -----END PGP SIGNATURE----- --=-=-=--