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Date: Tue, 29 Sep 2015 10:44:22 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>, Andy Lutomirski <luto@amacapital.net>,
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        "H. Peter Anvin" <hpa@zytor.com>, Oleg Nesterov <oleg@redhat.com>,
        Waiman Long <waiman.long@hp.com>, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 06/11] x86/virt/guest/xen: Remove use of pgd_list from
 the Xen guest code
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, Sep 21, 2015 at 11:23 PM, Ingo Molnar <mingo@kernel.org> wrote:
> > xen_mm_pin_all()/unpin_all() are used to implement full guest instance
> > suspend/restore. It's a stop-all method that needs to iterate through
> > all allocated pgds in the system to fix them up for Xen's use.
> 
> And _this_ is why I'd reall ylike that "for_each_mm()" helper.
> 
> Yeah, yeah, maybe it would require syntax like
> 
>     for_each_mm (tsk, mm) {
>         ...
>     } end_for_each_mm(mm);
> 
> to do variable allocation things or cleanups (ie "end_for_each_mm()" might drop 
> the task lock etc), but wouldn't that still be better than this complex 
> boilerplate thing?

Yeah, agreed absolutely.

Thanks,

	Ingo