From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oren Laadan Subject: Re: [Devel] Re: [PATCH 08/10] Introduce functions to restart a process Date: Wed, 22 Oct 2008 11:25:03 -0400 Message-ID: <48FF45CF.5000306@cs.columbia.edu> References: <1224285098-573-1-git-send-email-major@openvz.org> <200810221249.55600.major@openvz.org> <20081022092502.GW15171@hawkmoon.kerlabs.com> <200810221412.14174.major@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200810221412.14174.major-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Andrey Mirkin Cc: Louis.Rilling-aw0BnHfMbSpBDgjK7y7TUQ@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Cedric Le Goater , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Pavel Emelyanov List-Id: containers.vger.kernel.org Andrey Mirkin wrote: > On Wednesday 22 October 2008 13:25 Louis Rilling wrote: >> On Wed, Oct 22, 2008 at 12:49:54PM +0400, Andrey Mirkin wrote: >>> On Monday 20 October 2008 13:23 Cedric Le Goater wrote: >>>> Hello Andrey ! >>>> >>>>> diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S >>>>> index 109792b..a4848a3 100644 >>>>> --- a/arch/x86/kernel/entry_32.S >>>>> +++ b/arch/x86/kernel/entry_32.S >>>>> @@ -225,6 +225,7 @@ ENTRY(ret_from_fork) >>>>> GET_THREAD_INFO(%ebp) >>>>> popl %eax >>>>> CFI_ADJUST_CFA_OFFSET -4 >>>>> +ret_from_fork_tail: >>>>> pushl $0x0202 # Reset kernel eflags >>>>> CFI_ADJUST_CFA_OFFSET 4 >>>>> popfl >>>>> @@ -233,6 +234,26 @@ ENTRY(ret_from_fork) >>>>> CFI_ENDPROC >>>>> END(ret_from_fork) >>>>> >>>>> +ENTRY(i386_ret_from_resume) >>>>> + CFI_STARTPROC >>>>> + pushl %eax >>>>> + CFI_ADJUST_CFA_OFFSET 4 >>>>> + call schedule_tail >>>>> + GET_THREAD_INFO(%ebp) >>>>> + popl %eax >>>>> + CFI_ADJUST_CFA_OFFSET -4 >>>>> + movl (%esp), %eax >>>>> + testl %eax, %eax >>>>> + jz 1f >>>>> + pushl %esp >>>>> + call *%eax >>>>> + addl $4, %esp >>>>> +1: >>>>> + addl $256, %esp >>>>> + jmp ret_from_fork_tail >>>>> + CFI_ENDPROC >>>>> +END(i386_ret_from_resume) >>>> Could you explain why you need to do this >>>> >>>> call *%eax >>>> >>>> is it related to the freezer code ? >>> It is not related to the freezer code actually. >>> That is needed to restart syscalls. Right now I don't have a code in my >>> patchset which restarts a syscall, but later I plan to add it. >>> In OpenVZ checkpointing we restart syscalls if process was caught in >>> syscall during checkpointing. >> Do you checkpoint uninterruptible syscalls as well? If only interruptible >> syscalls are checkpointed, I'd say that either this syscall uses >> ERESTARTSYS or ERESTART_RESTARTBLOCK, and then signal handling code already >> does the trick, or this syscall does not restart itself when interrupted, >> and well, this is life, userspace just sees -EINTR, which is allowed by the >> syscall spec. >> Actually this is how we checkpoint/migrate tasks in interruptible syscalls >> in Kerrighed and this works. > > We checkpoint only interruptible syscalls. Some syscalls do not restart > themself, that is why after restarting a process we restart syscall to > complete it. Can you please elaborate on this ? I don't recall having had issues with that. Thanks, Oren. > > Andrey > _______________________________________________ > Containers mailing list > Containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org > https://lists.linux-foundation.org/mailman/listinfo/containers From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754203AbYJVP1H (ORCPT ); Wed, 22 Oct 2008 11:27:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752552AbYJVP0x (ORCPT ); Wed, 22 Oct 2008 11:26:53 -0400 Received: from serrano.cc.columbia.edu ([128.59.29.6]:40282 "EHLO serrano.cc.columbia.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752294AbYJVP0w (ORCPT ); Wed, 22 Oct 2008 11:26:52 -0400 Message-ID: <48FF45CF.5000306@cs.columbia.edu> Date: Wed, 22 Oct 2008 11:25:03 -0400 From: Oren Laadan Organization: Columbia University User-Agent: Thunderbird 2.0.0.16 (X11/20080707) MIME-Version: 1.0 To: Andrey Mirkin CC: Louis.Rilling@kerlabs.com, containers@lists.linux-foundation.org, Cedric Le Goater , linux-kernel@vger.kernel.org, Pavel Emelyanov Subject: Re: [Devel] Re: [PATCH 08/10] Introduce functions to restart a process References: <1224285098-573-1-git-send-email-major@openvz.org> <200810221249.55600.major@openvz.org> <20081022092502.GW15171@hawkmoon.kerlabs.com> <200810221412.14174.major@openvz.org> In-Reply-To: <200810221412.14174.major@openvz.org> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-No-Spam-Score: Local Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrey Mirkin wrote: > On Wednesday 22 October 2008 13:25 Louis Rilling wrote: >> On Wed, Oct 22, 2008 at 12:49:54PM +0400, Andrey Mirkin wrote: >>> On Monday 20 October 2008 13:23 Cedric Le Goater wrote: >>>> Hello Andrey ! >>>> >>>>> diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S >>>>> index 109792b..a4848a3 100644 >>>>> --- a/arch/x86/kernel/entry_32.S >>>>> +++ b/arch/x86/kernel/entry_32.S >>>>> @@ -225,6 +225,7 @@ ENTRY(ret_from_fork) >>>>> GET_THREAD_INFO(%ebp) >>>>> popl %eax >>>>> CFI_ADJUST_CFA_OFFSET -4 >>>>> +ret_from_fork_tail: >>>>> pushl $0x0202 # Reset kernel eflags >>>>> CFI_ADJUST_CFA_OFFSET 4 >>>>> popfl >>>>> @@ -233,6 +234,26 @@ ENTRY(ret_from_fork) >>>>> CFI_ENDPROC >>>>> END(ret_from_fork) >>>>> >>>>> +ENTRY(i386_ret_from_resume) >>>>> + CFI_STARTPROC >>>>> + pushl %eax >>>>> + CFI_ADJUST_CFA_OFFSET 4 >>>>> + call schedule_tail >>>>> + GET_THREAD_INFO(%ebp) >>>>> + popl %eax >>>>> + CFI_ADJUST_CFA_OFFSET -4 >>>>> + movl (%esp), %eax >>>>> + testl %eax, %eax >>>>> + jz 1f >>>>> + pushl %esp >>>>> + call *%eax >>>>> + addl $4, %esp >>>>> +1: >>>>> + addl $256, %esp >>>>> + jmp ret_from_fork_tail >>>>> + CFI_ENDPROC >>>>> +END(i386_ret_from_resume) >>>> Could you explain why you need to do this >>>> >>>> call *%eax >>>> >>>> is it related to the freezer code ? >>> It is not related to the freezer code actually. >>> That is needed to restart syscalls. Right now I don't have a code in my >>> patchset which restarts a syscall, but later I plan to add it. >>> In OpenVZ checkpointing we restart syscalls if process was caught in >>> syscall during checkpointing. >> Do you checkpoint uninterruptible syscalls as well? If only interruptible >> syscalls are checkpointed, I'd say that either this syscall uses >> ERESTARTSYS or ERESTART_RESTARTBLOCK, and then signal handling code already >> does the trick, or this syscall does not restart itself when interrupted, >> and well, this is life, userspace just sees -EINTR, which is allowed by the >> syscall spec. >> Actually this is how we checkpoint/migrate tasks in interruptible syscalls >> in Kerrighed and this works. > > We checkpoint only interruptible syscalls. Some syscalls do not restart > themself, that is why after restarting a process we restart syscall to > complete it. Can you please elaborate on this ? I don't recall having had issues with that. Thanks, Oren. > > Andrey > _______________________________________________ > Containers mailing list > Containers@lists.linux-foundation.org > https://lists.linux-foundation.org/mailman/listinfo/containers