From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linux-foundation.org ([65.172.181.25]:45932 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161532AbXDXKKb (ORCPT ); Tue, 24 Apr 2007 06:10:31 -0400 Date: Tue, 24 Apr 2007 03:09:24 -0700 From: Andrew Morton Subject: Re: [PATCH] kthread: Enhance kthread_stop to abort interruptible sleeps Message-Id: <20070424030924.be44ebfa.akpm@linux-foundation.org> In-Reply-To: References: <20070413130236.GA173@tv-sign.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org To: "Eric W. Biederman" Cc: Oleg Nesterov , Davide Libenzi , Ingo Molnar , Linus Torvalds , "Rafael J. Wysocki" , Roland McGrath , Rusty Russell , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org List-ID: On Fri, 13 Apr 2007 21:13:13 -0600 ebiederm@xmission.com (Eric W. Biederman) wrote: > This patch reworks kthread_stop so it is more flexible and it causes > the target kthread to abort interruptible sleeps. Allowing a larger > class of kernel threads to use to the kthread API. > > The changes start by defining TIF_KTHREAD_STOP on all architectures. > TIF_KTHREAD_STOP is a per process flag that I can set from another > process to indicate that a kernel thread should stop. > > wake_up_process in kthread_stop has been replaced by signal_wake_up > ensuring that the kernel thread if sleeping is woken up in a timely > manner and with TIF_SIGNAL_PENDING set, which causes us to break out > of interruptible sleeps. > > recalc_signal_pending was modified to keep TIF_SIGNAL_PENDING set for > as long as TIF_KTHREAD_STOP is set. > > Arbitrary paths to do_exit are now allowed. I have placed a > completion on the thread stack and pointed vfork_done at it, when the > mm_release is called from do_exit the completion will be called. > Since the completion is stored on the stack it is important that > kthread() now calls do_exit ensuring the stack frame that holds the > completion is never released, and so that our exit_code is certain to > make it unchanged all the way to do_exit. > > To allow kthread_stop to read the process exit code when exit_mm wakes > it up I have moved the setting of exit_code to the beginning of > do_exit. This patch causes this oops: http://userweb.kernel.org/~akpm/s5000508.jpg with this config: http://userweb.kernel.org/~akpm/config-x.txt