From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
David Vrabel <david.vrabel@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [Xen-devel] Re: [PATCH 0/6] xen: don't call vmalloc_sync_all() when mapping foreign pages
Date: Thu, 22 Sep 2011 12:06:58 +0100 [thread overview]
Message-ID: <alpine.DEB.2.00.1109221131390.8700@kaball-desktop> (raw)
In-Reply-To: <4E7A3394.3090806@goop.org>
On Wed, 21 Sep 2011, Jeremy Fitzhardinge wrote:
> On 09/21/2011 03:42 AM, Stefano Stabellini wrote:
> > On Thu, 15 Sep 2011, Jeremy Fitzhardinge wrote:
> >> This series is relying on regular ram mappings are already synced to all
> >> tasks, but I'm not sure that's necessarily guaranteed (for example, if
> >> you hotplug new memory into the domain, the new pages won't be mapped
> >> into every mm unless they're synced).
> > the series is using GFP_KERNEL, so this problem shouldn't occur, right?
>
> What properties do you think GFP_KERNEL guarantees?
That the memory is below 4G and always mapped in the kernel 1:1 region.
Regarding memory hotplug it looks like that x86_32 is mapping new memory
ZONE_HIGHMEM, therefore avoiding any problems with GFP_KERNEL allocations.
On the other hand x86_64 is mapping the memory ZONE_NORMAL and calling
init_memory_mapping on the new range right away. AFAICT changes to
the 1:1 mapping in init_mm are automatically synced across all mm's
because the pgd is shared?
next prev parent reply other threads:[~2011-09-22 11:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-15 12:40 David Vrabel
2011-09-15 12:40 ` [PATCH 1/6] xen: add functions for mapping foreign pages over pages David Vrabel
2011-09-15 12:40 ` [PATCH 2/6] block: xen-blkback: use API provided by xenbus module to map rings David Vrabel
2011-09-15 12:40 ` [PATCH 3/6] net: xen-netback: " David Vrabel
2011-09-15 12:40 ` [PATCH 4/6] xen: xen-pciback: use xenbus_map_ring_page() " David Vrabel
2011-09-15 12:40 ` [PATCH 5/6] xen: xenbus: remove xenbus_map_ring_valloc() and xenbus_map_ring_vfree() David Vrabel
2011-09-15 12:40 ` [PATCH 6/6] mm: remove vmalloc_sync_all() from alloc_vm_area() David Vrabel
2011-09-15 21:37 ` [PATCH 0/6] xen: don't call vmalloc_sync_all() when mapping foreign pages Jeremy Fitzhardinge
2011-09-21 10:42 ` Stefano Stabellini
2011-09-21 18:57 ` [Xen-devel] " Jeremy Fitzhardinge
2011-09-22 11:06 ` Stefano Stabellini [this message]
2011-09-22 21:19 ` Jeremy Fitzhardinge
2011-09-23 10:53 ` Stefano Stabellini
2011-09-23 11:18 ` David Vrabel
2011-09-21 14:44 ` David Vrabel
2011-09-23 15:11 ` David Vrabel
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