From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4884 invoked by alias); 27 Oct 2007 01:40:41 -0000 Received: (qmail 4875 invoked by uid 22791); 27 Oct 2007 01:40:41 -0000 X-Spam-Check-By: sourceware.org Received: from e1.ny.us.ibm.com (HELO e1.ny.us.ibm.com) (32.97.182.141) by sourceware.org (qpsmtpd/0.31) with ESMTP; Sat, 27 Oct 2007 01:40:39 +0000 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e1.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id l9R1eXop009546 for ; Fri, 26 Oct 2007 21:40:33 -0400 Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id l9R1eXcm140170 for ; Fri, 26 Oct 2007 21:40:33 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l9R1eWKJ029263 for ; Fri, 26 Oct 2007 21:40:32 -0400 Received: from [9.67.179.224] (wecm-9-67-179-224.wecm.ibm.com [9.67.179.224]) by d01av01.pok.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id l9R1eVcx029252; Fri, 26 Oct 2007 21:40:31 -0400 Subject: Re: Apparent kernel bug with GDB on ppc405 From: Josh Boyer To: benh@kernel.crashing.org Cc: Daniel Jacobowitz , gdb@sourceware.org, linuxppc-embedded@ozlabs.org, Matt Mackall In-Reply-To: <1193448983.18243.16.camel@pasglop> References: <20071024194640.GB19691@waste.org> <20071024204215.GC19691@waste.org> <20071024215421.GF19691@waste.org> <20071024223250.GI19691@waste.org> <20071024224130.GA30819@caradoc.them.org> <1193363482.7018.41.camel@pasglop> <20071026154126.28082129@weaponx.rchland.ibm.com> <1193448983.18243.16.camel@pasglop> Content-Type: text/plain Date: Sat, 27 Oct 2007 01:40:00 -0000 Message-Id: <1193448456.25515.63.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.8.0 (2.8.0-33.0.1.el5) Content-Transfer-Encoding: 7bit Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2007-10/txt/msg00283.txt.bz2 On Sat, 2007-10-27 at 11:36 +1000, Benjamin Herrenschmidt wrote: > On Fri, 2007-10-26 at 15:41 -0500, Josh Boyer wrote: > > On Fri, 26 Oct 2007 11:51:22 +1000 > > Benjamin Herrenschmidt wrote: > > > > > > > > On Wed, 2007-10-24 at 18:41 -0400, Daniel Jacobowitz wrote: > > > > On Wed, Oct 24, 2007 at 05:32:50PM -0500, Matt Mackall wrote: > > > > > Not completely implausible, but a) why isn't this seen on basically > > > > > every machine with software TLB? b) why does -local- GDB, which is > > > > > presumably doing much less work than gdbserver + network stack, not fail? > > > > > > > > You said it yourself. Local gdb does more work -> blows through more > > > > TLB entries. > > > > > > > > I can't answer you about the other half, but I'm pretty sure TLB > > > > invalidation is already supposed to be happening... somewhere. > > > > > > Yes. do_wp_page() -> ptep_clear_flush() -> flush_tlb_page() > > > > Aren't there cases in do_wp_page that don't call ptep_clear_flush? > > Seems anonymous pages, and possibly shared writeable pages skip that > > step if reuse is true. > > Nah, if that was broken, everybody would be in bad shape. I think I know > what's up, see my other email. Yeah, I figured that out after I sent this anyway. In those cases it should likely get flushed from ptep_set_access_flags. josh