From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Fri, 17 Aug 2012 13:27:35 +0000 (-0400)
Subject: xen/p2m: Reuse existing P2M leafs if they are filled with 1:1 PFNs or INVALID.
X-Git-Tag: v3.6-rc4~12^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=250a41e0ecc433cdd553a364d0fc74c766425209;p=pandora-kernel.git

xen/p2m: Reuse existing P2M leafs if they are filled with 1:1 PFNs or INVALID.

If P2M leaf is completly packed with INVALID_P2M_ENTRY or with
1:1 PFNs (so IDENTITY_FRAME type PFNs), we can swap the P2M leaf
with either a p2m_missing or p2m_identity respectively. The old
page (which was created via extend_brk or was grafted on from the
mfn_list) can be re-used for setting new PFNs.

This also means we can remove git commit:
5bc6f9888db5739abfa0cae279b4b442e4db8049
xen/p2m: Reserve 8MB of _brk space for P2M leafs when populating back
which tried to fix this.

and make the amount that is required to be reserved much smaller.

CC: stable@vger.kernel.org # for 3.5 only.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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