From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olaf Hering <olaf@aepfle.de>
Subject: Re: [PATCH 6 of 8] x86/mm: Properly account for paged
	out pages
Date: Thu, 26 Jan 2012 13:11:06 +0100
Message-ID: <20120126121105.GB545@aepfle.de>
References: <patchbomb.1327550004@xdev.gridcentric.ca>
	<d4336e35f0bcb4fcb060.1327550010@xdev.gridcentric.ca>
	<20120126095401.GC21629@aepfle.de>
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To: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Cc: andres@gridcentric.ca, xen-devel@lists.xensource.com, tim@xen.org, adin@gridcentric.ca
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On Thu, Jan 26, Andres Lagar-Cavilla wrote:

> there is a put_page in case things go wrong, after the alloc_domheap_page
> call. So doing the decrement at alloc is a bit too soon.

Thats probably true.

But in the case of failure the guest will likely hang soon. Is the
copy_from_user() (and p2m_mem_paging_prep itself) restartable? If not,
the guest should probably be crashed.  The way xenpaging_populate_page()
is written right now, it will just exit, EFAULT isnt caught.

Olaf