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From: Andy Lutomirski <luto@amacapital.net>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>,
	Pavel Emelyanov <xemul@parallels.com>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Borislav Petkov <bp@alien8.de>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	X86 ML <x86@kernel.org>,
	Ruslan Kabatsayev <b7.10110111@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Getting rid of dynamic TASK_SIZE (on x86, at least)
Date: Tue, 10 May 2016 13:29:50 -0700	[thread overview]
Message-ID: <CALCETrU4me1X7oTriLgFQpTqwaebMsT5sdYZzjC=_EERXNbqzA@mail.gmail.com> (raw)
In-Reply-To: <20160510182055.GA24868@redhat.com>

On May 10, 2016 11:21 AM, "Oleg Nesterov" <oleg@redhat.com> wrote:
>
> On 05/10, Andy Lutomirski wrote:
> >
> >  - xol_add_vma: This one is weird: uprobes really is doing something
> > behind the task's back, and the addresses need to be consistent with
> > the address width.  I'm not quite sure what to do here.
>
> It can use mm->task_size instead, plus this is just a hint. And perhaps
> mm->task_size should have more users, say get_unmapped_area...

Ick.  I hadn't noticed mm->task_size.  We have a *lot* of different
indicators of task size.  mm->task_size appears to have basically no
useful uses except maybe for ppc.

On x86, bitness can change without telling the kernel, and tasks
running in 64-bit mode can do 32-bit syscalls.

So maybe I should add mm->task_size to my list of things that would be
nice to remove.  Or maybe I'm just tilting at windmills.

>
> Not sure we should really get rid of dynamic TASK_SIZE completely, but
> personally I agree it looks a bit ugly.
>
> Oleg.
>

WARNING: multiple messages have this Message-ID (diff)
From: Andy Lutomirski <luto@amacapital.net>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>,
	Pavel Emelyanov <xemul@parallels.com>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Borislav Petkov <bp@alien8.de>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	X86 ML <x86@kernel.org>,
	Ruslan Kabatsayev <b7.10110111@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Getting rid of dynamic TASK_SIZE (on x86, at least)
Date: Tue, 10 May 2016 13:29:50 -0700	[thread overview]
Message-ID: <CALCETrU4me1X7oTriLgFQpTqwaebMsT5sdYZzjC=_EERXNbqzA@mail.gmail.com> (raw)
In-Reply-To: <20160510182055.GA24868@redhat.com>

On May 10, 2016 11:21 AM, "Oleg Nesterov" <oleg@redhat.com> wrote:
>
> On 05/10, Andy Lutomirski wrote:
> >
> >  - xol_add_vma: This one is weird: uprobes really is doing something
> > behind the task's back, and the addresses need to be consistent with
> > the address width.  I'm not quite sure what to do here.
>
> It can use mm->task_size instead, plus this is just a hint. And perhaps
> mm->task_size should have more users, say get_unmapped_area...

Ick.  I hadn't noticed mm->task_size.  We have a *lot* of different
indicators of task size.  mm->task_size appears to have basically no
useful uses except maybe for ppc.

On x86, bitness can change without telling the kernel, and tasks
running in 64-bit mode can do 32-bit syscalls.

So maybe I should add mm->task_size to my list of things that would be
nice to remove.  Or maybe I'm just tilting at windmills.

>
> Not sure we should really get rid of dynamic TASK_SIZE completely, but
> personally I agree it looks a bit ugly.
>
> Oleg.
>

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  reply	other threads:[~2016-05-10 20:30 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-10 16:07 Getting rid of dynamic TASK_SIZE (on x86, at least) Andy Lutomirski
2016-05-10 16:07 ` Andy Lutomirski
2016-05-10 16:30 ` Cyrill Gorcunov
2016-05-10 16:30   ` Cyrill Gorcunov
2016-05-10 16:45   ` Andy Lutomirski
2016-05-10 16:45     ` Andy Lutomirski
2016-05-10 17:05     ` Cyrill Gorcunov
2016-05-10 17:05       ` Cyrill Gorcunov
2016-05-10 17:26       ` Andy Lutomirski
2016-05-10 17:26         ` Andy Lutomirski
2016-05-10 17:49         ` Cyrill Gorcunov
2016-05-10 17:49           ` Cyrill Gorcunov
2016-05-10 21:11           ` Andy Lutomirski
2016-05-10 21:11             ` Andy Lutomirski
2016-05-11  5:59             ` Cyrill Gorcunov
2016-05-11  5:59               ` Cyrill Gorcunov
2016-05-10 18:20 ` Oleg Nesterov
2016-05-10 18:20   ` Oleg Nesterov
2016-05-10 20:29   ` Andy Lutomirski [this message]
2016-05-10 20:29     ` Andy Lutomirski
2016-05-11 18:08     ` Oleg Nesterov
2016-05-11 18:08       ` Oleg Nesterov

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