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From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Xenomai <xenomai@xenomai.org>
Subject: Re: [Xenomai] [PATCH v3] ipipe x86 mm: handle huge pages in memory pinning
Date: Wed, 3 Feb 2016 15:38:45 +0100	[thread overview]
Message-ID: <20160203143845.GC32138@hermes.click-hack.org> (raw)
In-Reply-To: <56B20F2E.2020404@siemens.com>

On Wed, Feb 03, 2016 at 03:31:10PM +0100, Jan Kiszka wrote:
> On 2016-02-03 15:24, Gilles Chanteperdrix wrote:
> > On Wed, Feb 03, 2016 at 01:59:25PM +0100, Henning Schild wrote:
> >> In 4.1 huge page mapping of io memory was introduced, enable ipipe to
> >> handle that when pinning kernel memory.
> >>
> >> change that introduced the feature
> >> 0f616be120c632c818faaea9adcb8f05a7a8601f
> > 
> > Could we have an assessment of whether avoiding the call to
> > __ipipe_pin_range_mapping in upper layers makes the patch simpler?
> 
> For that, we first of all need to recapitulate how
> __ipipe_pin_range_globally is/was supposed to work at all.
> 
> I tried to restore details but I'm specifically failing regarding that
> "globally". To my understanding, the vmalloc_sync_one of x86 transfers
> at best mappings from init_mm to the current mm one, but not to all mm
> in the systems.

__ipipe_pin_range_globally calls vmalloc_sync_one for all pgds in
the system. This is pretty ugly, not very scalable, but if you do
not do that, each access to an ioremap/vmalloc area in, say, an
interrupt handler, causes a fault for processes that do not have the
mapping in their page tables. Such processes exist if they were
created before the call to ioremap/vmalloc. Another possible fix to
this issue is to allow handling that kind of faults over the head
domain without switching to secondary domain.

-- 
					    Gilles.
https://click-hack.org


  reply	other threads:[~2016-02-03 14:38 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-14 17:34 [Xenomai] ipipe x86_64 huge page ioremap Henning Schild
2016-01-15  8:32 ` Philippe Gerum
2016-01-15 12:34   ` Jan Kiszka
2016-02-02 17:43   ` Henning Schild
2016-02-03 15:07     ` Philippe Gerum
2016-02-03 15:48       ` Philippe Gerum
2016-02-04 11:43       ` Henning Schild
2016-01-26 15:20 ` [Xenomai] [PATCH] ipipe x86 mm: handle huge pages in memory pinning Henning Schild
2016-01-26 20:18   ` Jan Kiszka
2016-01-27  9:54     ` Henning Schild
2016-01-27 10:31       ` Jan Kiszka
2016-01-27 10:44         ` Philippe Gerum
2016-01-27 10:46           ` Philippe Gerum
2016-01-27 13:41   ` [Xenomai] [PATCH v2] " Henning Schild
2016-01-28 10:53     ` Philippe Gerum
2016-01-28 20:53       ` Henning Schild
2016-01-29 17:11         ` Philippe Gerum
2016-01-29 18:39           ` Gilles Chanteperdrix
2016-02-02 12:08             ` Henning Schild
2016-02-02 13:58               ` Philippe Gerum
2016-02-02 16:38                 ` Henning Schild
2016-02-02 16:39                   ` Jan Kiszka
2016-02-02 19:26                   ` Gilles Chanteperdrix
2016-02-03 11:35                     ` Henning Schild
2016-02-02 14:18               ` Philippe Gerum
2016-02-02 16:30                 ` Henning Schild
2016-02-02 11:41           ` Henning Schild
2016-02-03 12:59     ` [Xenomai] [PATCH v3] " Henning Schild
2016-02-03 14:24       ` Gilles Chanteperdrix
2016-02-03 14:31         ` Jan Kiszka
2016-02-03 14:38           ` Gilles Chanteperdrix [this message]
2016-02-03 14:51             ` Jan Kiszka
2016-02-03 15:02               ` Gilles Chanteperdrix
2016-02-03 15:14                 ` Jan Kiszka
2016-02-04 11:53         ` Henning Schild
2016-02-08  8:44       ` Henning Schild
2016-03-07  7:58         ` Henning Schild

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