From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cyrill Gorcunov <gorcunov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>
Subject: Re: [Announce] Checkpoint-restore tool v0.1
Date: Tue, 31 Jul 2012 14:16:03 +0400
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To: richard -rw- weinberger <richard.weinberger-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Pavel Emelyanov <xemul-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>, Linux Kernel Mailing List <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "lwn-T1hC0tSOHrs@public.gmane.org" <lwn-T1hC0tSOHrs@public.gmane.org>, "criu-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org" <criu-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>, "users-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org" <users-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>, Containers <containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>, cgroups mailinglist <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>

On Tue, Jul 31, 2012 at 12:08:22PM +0200, richard -rw- weinberger wrote:
> On Tue, Jul 31, 2012 at 11:54 AM, Pavel Emelyanov <xemul-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org> wrote:
> >> Yeah, but I fear it's not that easy.
> >> We'd have to change crtools to work without ptrace().
> >
> > Well, this is hard. Using ptrace saved us from having many special-purpose
> > APIs for dumping various stuff (there will be an article about it). Thus I
> > don't know which way is simpler -- stop using ptrace or teach ptrece to allow
> > several tracers to attach to one task %)
> 
> Allowing multiple tracers in a safe way is IMHO even more harder.
> 
> BTW:  While reading prctl_set_mm() I noticed two things.
> 1.  Why isn't the return value of find_vma() verified?

prctl_set_mm
	vma = find_vma(mm, addr);
	...
	if (!vma) {
		error = -EFAULT;
		goto out;
	}

these values are used in procfs statistics only. So I don't get
which verify you mean here.

> It looks like one can set an addr which does not belong to any vma.
> 2. What will happen if addr is not page aligned?

you'll have a bit weird output in procfs stat (probably I should add
page alignment check here).

	Cyrill