From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f54.google.com (mail-la0-f54.google.com [209.85.215.54]) by kanga.kvack.org (Postfix) with ESMTP id A318E900021 for ; Tue, 28 Oct 2014 12:57:51 -0400 (EDT) Received: by mail-la0-f54.google.com with SMTP id gm9so979898lab.41 for ; Tue, 28 Oct 2014 09:57:50 -0700 (PDT) Received: from mail-la0-x231.google.com (mail-la0-x231.google.com. [2a00:1450:4010:c03::231]) by mx.google.com with ESMTPS id ri5si3359614lbb.115.2014.10.28.09.57.49 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 28 Oct 2014 09:57:49 -0700 (PDT) Received: by mail-la0-f49.google.com with SMTP id ge10so984032lab.8 for ; Tue, 28 Oct 2014 09:57:49 -0700 (PDT) From: Michal Nazarewicz Subject: Re: CMA: test_pages_isolated failures in alloc_contig_range In-Reply-To: <544F9EAA.5010404@hurleysoftware.com> References: <2457604.k03RC2Mv4q@avalon> <544F9EAA.5010404@hurleysoftware.com> Date: Tue, 28 Oct 2014 17:57:45 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Peter Hurley , Laurent Pinchart , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org, Bartlomiej Zolnierkiewicz , Minchan Kim , Andrew Morton > On 10/28/2014 08:38 AM, Michal Nazarewicz wrote: >> Like Laura wrote, the message is not (should not be) a problem in >> itself: > > [...] > >> So as you can see cma_alloc will try another part of the cma region if >> test_pages_isolated fails. >>=20 >> Obviously, if CMA region is fragmented or there's enough space for only >> one allocation of required size isolation failures will cause allocation >> failures, so it's best to avoid them, but they are not always avoidable. >>=20 >> To debug you would probably want to add more debug information about the >> page (i.e. data from struct page) that failed isolation after the >> pr_warn in alloc_contig_range. On Tue, Oct 28 2014, Peter Hurley wrote: > If the message does not indicate an actual problem, then its printk level= is > too high. These messages have been reported when using 3.16+ distro kerne= ls. I think it could be argued both ways. The condition is not an error, since in many cases cma_alloc will be able to continue, but it *is* an undesired state. As such it's not an error but feels to me a bit more then just information, hence a warning. I don't care either way, though. --=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-- -- 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