From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: Re: A regression in recent 3.2 kernel: bdi_dirty_limit() divide error Date: Tue, 10 Jan 2012 22:38:05 +0800 Message-ID: <20120110143805.GA8320@localhost> References: <20120109040445.GB31049@localhost> <1326205945.62365.YahooMailClassic@web161603.mail.bf1.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Peter Zijlstra , linux-fsdevel@vger.kernel.org, LKML To: =?utf-8?B?0JjQu9GM0Y8g0KLRg9C80LDQudC60LjQvQ==?= Return-path: Received: from mga03.intel.com ([143.182.124.21]:36261 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751111Ab2AJOij (ORCPT ); Tue, 10 Jan 2012 09:38:39 -0500 Content-Disposition: inline In-Reply-To: <1326205945.62365.YahooMailClassic@web161603.mail.bf1.yahoo.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Jan 10, 2012 at 06:32:25AM -0800, =D0=98=D0=BB=D1=8C=D1=8F =D0=A2= =D1=83=D0=BC=D0=B0=D0=B9=D0=BA=D0=B8=D0=BD wrote: > Hello, Mr. Fengguang. >=20 > This latter patch fixed the problem completely! I've tested vanilla 3= =2E2 with both patches applied and with only the latter one, results ar= e the same:=20 > - first of all the initial problem solved. I have no "divide error" (= not sure if this panic) now. > - doing daily desktop stuff (e.g. web browsing, movie playback, book = reading etc) also without any errors as well as compiling packages. >=20 > So, I can confirm the problem is solved completely.=20 > Thank you and your colleagues very much for you fast response and act= ive help! I am very grateful! =20 Ilya, thank you too for your report and testing! I'll submit the patch = right now. Thanks, =46engguang > --- =D0=9F=D0=BD, 9.1.12, Wu Fengguang =D0=BF=D0= =B8=D1=88=D0=B5=D1=82: >=20 > > =D0=9E=D1=82: Wu Fengguang > > =D0=A2=D0=B5=D0=BC=D0=B0: Re: A regression in recent 3.2 kernel: bd= i_dirty_limit() divide error > > =D0=9A=D0=BE=D0=BC=D1=83: "Peter Zijlstra" > > =D0=9A=D0=BE=D0=BF=D0=B8=D1=8F: "=D0=98=D0=BB=D1=8C=D1=8F =D0=A2=D1= =83=D0=BC=D0=B0=D0=B9=D0=BA=D0=B8=D0=BD" , "LK= ML" , linux-fsdevel@vger.kernel.org > > =D0=94=D0=B0=D1=82=D0=B0: =D0=9F=D0=BE=D0=BD=D0=B5=D0=B4=D0=B5=D0=BB= =D1=8C=D0=BD=D0=B8=D0=BA, 9 =D1=8F=D0=BD=D0=B2=D0=B0=D1=80=D1=8C 2012, = 7:04 > > On Sun, Jan 08, 2012 at 11:19:14AM > > +0100, Peter Zijlstra wrote: > >=20 > > > But even then, we limit PROP_MAX_SHIFT to > > 3*BITS_PER_LONG/4, I don't > > > think that could ever overflow. > >=20 > > do_div() only uses the lower 32 bit value of the 64 bit > > denominator, > > which may happen to be 0. > >=20 > > The denominator is not really 64 bit, but limited by > > PROP_MAX_SHIFT =3D > > 48 bit, however that upper limit looks not enough. > >=20 > > Ilya, would you help try the attached patch instead? > >=20 > > Thanks, > > Fengguang > > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html