Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965937AbXFGC3I (ORCPT ); Wed, 6 Jun 2007 22:29:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S935753AbXFGC2z (ORCPT ); Wed, 6 Jun 2007 22:28:55 -0400 Received: from saraswathi.solana.com ([198.99.130.12]:58638 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935757AbXFGC2z (ORCPT ); Wed, 6 Jun 2007 22:28:55 -0400 Date: Wed, 6 Jun 2007 22:20:02 -0400 From: Jeff Dike To: Paul Mackerras Cc: Benjamin Herrenschmidt , Nicholas Miell , Davide Libenzi , Linus Torvalds , Linux Kernel list , Andrew Morton Subject: Re: signalfd API issues (was Re: [PATCH/RFC] signal races/bugs, losing TIF_SIGPENDING and other woes) Message-ID: <20070607022002.GA11977@c2.user-mode-linux.org> References: <1181023787.2785.14.camel@entropy> <1181028453.31677.127.camel@localhost.localdomain> <1181087462.2788.8.camel@entropy> <1181088936.2788.10.camel@entropy> <1181091523.2788.28.camel@entropy> <1181098204.31677.158.camel@localhost.localdomain> <20070606125259.GA5491@c2.user-mode-linux.org> <18023.14494.889739.567439@cargo.ozlabs.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <18023.14494.889739.567439@cargo.ozlabs.ibm.com> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 958 Lines: 21 On Thu, Jun 07, 2007 at 08:43:42AM +1000, Paul Mackerras wrote: > What Ben was talking about was stealing a synchronous SEGV from a task > without stopping it, and as Ben says that makes no sense. > Intercepting a signal and stopping the task is reasonable, and that is > what ptrace does, and I assume also UML. It is, but I can also see UML stealing the SEGV from the child. The UML skas does this - a ptrace extension, PTRACE_FAULTINFO, is used to extract page fault information from the child, and other pieces of the patch are used to fix the fault without the child continuing until it's fixed. So, in this case, the child never sees the SEGV. Jeff -- Work email - jdike at linux dot intel dot com - 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/