Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751495Ab0AJGby (ORCPT ); Sun, 10 Jan 2010 01:31:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751264Ab0AJGbw (ORCPT ); Sun, 10 Jan 2010 01:31:52 -0500 Received: from mail-px0-f174.google.com ([209.85.216.174]:52308 "EHLO mail-px0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750983Ab0AJGbv (ORCPT ); Sun, 10 Jan 2010 01:31:51 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=Hi9bizQSR8ncy542cm6ZFPa0f+4VM/QPew8fnkr/B1scXsbSp0Sy4NbQ6414NtEga0 ceT7GQHRSM27O3dBFzL88lV6+bWlk4RTSa5OIlkistY34QfSewr8ZRyGPtIxtg+RHK2f lHITHr6StG3DyvkD8lCo/tHen4LdS2GmTTVNg= Date: Sun, 10 Jan 2010 14:33:35 +0800 From: =?utf-8?Q?Am=C3=A9rico?= Wang To: Andi Kleen Cc: linux-kernel@vger.kernel.org Subject: Re: 2.6.33 pagemap endless read loop Message-ID: <20100110063335.GA3005@hack> References: <20100110020955.GB25323@basil.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100110020955.GB25323@basil.fritz.box> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1563 Lines: 35 On Sun, Jan 10, 2010 at 03:09:55AM +0100, Andi Kleen wrote: > >An LTP run on x86-64/2.6.33-rc3 run right now results in "proc01" hanging > >lr-x------ 1 root root 64 2010-01-10 02:28 7 -> /proc/2679/task/2679/pagemap > >strace shows an endless loop of > >read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024 >read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024 >read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024 >read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024 >read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024 >read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024 >read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 10 > >cat of that file hangs in the same way so it seems like a kernel bug. >A cat of /proc/2679/pagemap also hangs, in fact any pagemap cat seems to. > Are you sure? On my 32bit machine, it runs for a long time, but finally exits. >From the document of pagemap, it is the mapping of all the virtual pages of a process, on x86-32, it should be 4G/4K = 1024*1024 pages, also that when you 'cat' it, tty layer is involved to display it too. -- Live like a child, think like the god. -- 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/