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Re: [Xen-devel] [PATCH][PVFB][LINUX] Fix possible sleep while holding sp

To: Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH][PVFB][LINUX] Fix possible sleep while holding spinlock
From: Markus Armbruster <armbru@xxxxxxxxxx>
Date: Fri, 15 Dec 2006 19:35:37 +0100
Cc: Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
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In-reply-to: <C1A89495.6290%keir@xxxxxxxxxxxxx> (Keir Fraser's message of "Fri, 15 Dec 2006 18:06:13 +0000")
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Keir Fraser <keir@xxxxxxxxxxxxx> writes:

> On 15/12/06 16:38, "Markus Armbruster" <armbru@xxxxxxxxxx> wrote:
>> This patch fixes the locking, but leaves open a race between
>> xenfb_update_screen() and do_no_page().  See the source code for a
>> detailed explanation of how it works, and where it fails.
> That's a bit of a shame. Is there any way we could use do_file_page() and
> have a populate hook (which gets to install the PTE itself)? Or are there
> lots of assumptions about VMAs that would take this path, assert
>  -- Keir

My colleages and I suspect we need a deep think about the problem.
But right now we can't spare the time for that.

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