From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Mackall Subject: Re: [Bug #15041] Pagemap endless read loop with LTP Date: Wed, 13 Jan 2010 18:15:36 -0600 Message-ID: <1263428136.29868.5058.camel@calx> References: <2375c9f91001121904h2857760akbf2dd2c9f7441fc5@mail.gmail.com> <201001132257.34123.rjw@sisk.pl> <20100113235010.GF24818@basil.fritz.box> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20100113235010.GF24818-u0/ZJuX+froe6aEkudXLsA@public.gmane.org> Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="iso-8859-1" To: Andi Kleen Cc: "Rafael J. Wysocki" , =?ISO-8859-1?Q?Am=E9rico?= Wang , Linux Kernel Mailing List , Kernel Testers List On Thu, 2010-01-14 at 00:50 +0100, Andi Kleen wrote: > On Wed, Jan 13, 2010 at 10:57:34PM +0100, Rafael J. Wysocki wrote: > > On Wednesday 13 January 2010, Am=C3=A9rico Wang wrote: > > > On Mon, Jan 11, 2010 at 6:32 AM, Rafael J. Wysocki = wrote: > > > > This message has been generated automatically as a part of a re= port > > > > of recent regressions. > > > > > > > > The following bug entry is on the current list of known regress= ions > > > > from 2.6.32. Please verify if it still should be listed and le= t me know > > > > (either way). > > > > > > > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=3D= 15041 > > > > Subject : Pagemap endless read loop with LTP > > > > Submitter : Andi Kleen > > > > Date : 2010-01-10 2:09 (1 days old) > > > > References : http://marc.info/?l=3Dlinux-kernel&m=3D126308= 941423848&w=3D4 > > > > > > >=20 > > > According to Andi's later reply, it shoud not be an endless loop, > > > it just takes a rather long time. > >=20 > > Andi? >=20 > It'll try to read 47 bits worth of 0s on 64bit x86-64.=20 >=20 > I haven't tried to wait until that finishes, but I estimate a few mon= ths of=20 > CPU time at least. >=20 > The interface is just misdesigned, but I guess we cannot do > anything about that for now. It's perfectly sensible. What's not sensible is reading the entirety of everything you find in /proc, something that just about every Linux admin figures out moments after running their first recursive grep. > LTP will just need to do a workaround. Or they could actually, you know, add a test of pagemap. Not much chanc= e of that, though - CVS reports it took them until 2005 to figure out tha= t skipping /proc/kcore was a good idea. --=20 http://selenic.com : development and support for Mercurial and Linux