From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 8 Sep 2001 19:11:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 8 Sep 2001 19:11:29 -0400 Received: from colorfullife.com ([216.156.138.34]:59146 "EHLO colorfullife.com") by vger.kernel.org with ESMTP id ; Sat, 8 Sep 2001 19:11:21 -0400 Message-ID: <000901c138bb$8e151270$010411ac@local> From: "Manfred Spraul" To: "Roger Larsson" Cc: , "Robert Love" , Subject: Re: [SMP lock BUG?] Re: Feedback on preemptible kernel patch Date: Sun, 9 Sep 2001 01:11:05 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > This is interesting. [Assumes UP Athlon - correct] > Note that all BUGs out in highmem.h:95 (kmap_atomic) > and that test is only on if you have enabled HIGHMEM_DEBUG > [my analyze is done with a 2.4.10-pre2 kernel, but I checked with > later patches and I do not think they fix it either...] > > The preemptive kernel puts more SMP stress on the kernel than > running with multiple CPUs. > > So this might be a potential bug in the kernel proper, running with > a SMP computer. No. It seems to be a missing ctx_sw_off() in highmem.h: kmap_atomic uses a per-cpu variable, thus ctx_sw_off() is needed in kmap_atomic, and ctx_sw_on() in kunmap_atomic(). -- Manfred