Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265577AbUABN40 (ORCPT ); Fri, 2 Jan 2004 08:56:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265578AbUABN4Z (ORCPT ); Fri, 2 Jan 2004 08:56:25 -0500 Received: from e1.ny.us.ibm.com ([32.97.182.101]:9112 "EHLO e1.ny.us.ibm.com") by vger.kernel.org with ESMTP id S265577AbUABNzj (ORCPT ); Fri, 2 Jan 2004 08:55:39 -0500 Date: Fri, 2 Jan 2004 19:30:26 +0530 From: Srivatsa Vaddagiri To: Manfred Spraul Cc: linux-kernel@vger.kernel.org, rusty@au1.ibm.com, lhcs-devel@lists.sourceforge.net, jun.nakajima@intel.com, asit.k.mallick@intel.com, sunil.saxena@intel.com, torvalds@osdl.org Subject: Re: [lhcs-devel] Re: in_atomic doesn't count local_irq_disable? Message-ID: <20040102193026.A19698@in.ibm.com> Reply-To: vatsa@in.ibm.com References: <3FF044A2.3050503@colorfullife.com> <20031230185615.A9292@in.ibm.com> <20031231190553.B9041@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20031231190553.B9041@in.ibm.com>; from vatsa@in.ibm.com on Wed, Dec 31, 2003 at 07:05:53PM +0530 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3556 Lines: 130 On Wed, Dec 31, 2003 at 07:05:53PM +0530, Srivatsa Vaddagiri wrote: > More debugging reveals that the page fault happens > always while doing a prefetch. The prefetch is > present inside list_for_each_entry macros. > > For now I have disabled the x86 prefetch function > to do nothing. > > The test seems to run fine so far w/o any of the > page faults I was experiencing. Will update > at the end of the overnight run if I hit the problem again. > > Wonder if prefetch has some issues on Intel x86 (P3) SMP systems? > Even after disabling prefetch, I continue to hit page-faults. With prefetch disabled, it _always_ traps because of trying to dereference a NULL pointer in a list-head. If I break-in into the debugger, the list-head is actually valid (no NULL pointer is present) and hence I don't understand why it read a NULL pointer value in a list head. With prefetch enabled it traps because of fetch from arbitrary (random) addresses. So I am no longer sure if this is a prefetch issue or/and a hotplug issue. I'm continuing to investigate and will post any new observation I make here. FYI, the /proc/cpuinfo output on my SMP system is as below: processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 10 model name : Pentium III (Cascades) stepping : 1 cpu MHz : 699.730 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse bogomips : 1376.25 processor : 1 vendor_id : GenuineIntel cpu family : 6 model : 10 model name : Pentium III (Cascades) stepping : 1 cpu MHz : 699.726 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse bogomips : 1396.73 processor : 2 vendor_id : GenuineIntel cpu family : 6 model : 10 model name : Pentium III (Cascades) stepping : 1 cpu MHz : 699.726 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse bogomips : 1396.73 processor : 3 vendor_id : GenuineIntel cpu family : 6 model : 10 model name : Pentium III (Cascades) stepping : 1 cpu MHz : 699.726 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse bogomips : 1396.73 -- Thanks and Regards, Srivatsa Vaddagiri, Linux Technology Center, IBM Software Labs, Bangalore, INDIA - 560017 - 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/