Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261907AbUDSVxF (ORCPT ); Mon, 19 Apr 2004 17:53:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261915AbUDSVxF (ORCPT ); Mon, 19 Apr 2004 17:53:05 -0400 Received: from zero.aec.at ([193.170.194.10]:27915 "EHLO zero.aec.at") by vger.kernel.org with ESMTP id S261907AbUDSVxD (ORCPT ); Mon, 19 Apr 2004 17:53:03 -0400 To: Fabiano Ramos cc: linux-kernel@vger.kernel.org Subject: Re: task switching at Page Faults References: <1MN62-7wz-5@gated-at.bofh.it> <1MNpu-7QI-35@gated-at.bofh.it> From: Andi Kleen Date: Mon, 19 Apr 2004 23:52:48 +0200 In-Reply-To: <1MNpu-7QI-35@gated-at.bofh.it> (Fabiano Ramos's message of "Mon, 19 Apr 2004 22:20:16 +0200") Message-ID: User-Agent: Gnus/5.110002 (No Gnus v0.2) Emacs/21.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 974 Lines: 26 Fabiano Ramos writes: > kernel", about 2.4, and the authors: > 1)assure that there is no process switch during > the execution of an eception handler (aka syscall). > they emphasize it. They're wrong. First the system call or exception can block and then when kernel code returns to user space it always checks if the time slice hasn't expired. > 2) say that the execption handler may not generate > exceptions, except for page faults. That's also incorrect. e.g. it can generate GPFs (e.g. when trying to load a segment register supplied by the user and it is not correct) and a few other exceptions in extreme cases. Usually these exceptions are handled without sleeping though. -Andi - 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/