linux-kernel - [PATCH 3.4 85/88] xen/balloon: Subtract from xen_released

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Message-Id: <20140610002427.299412134@linuxfoundation.org>
Date:	Mon,  9 Jun 2014 17:25:35 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, David Vrabel <david.vrabel@...rix.com>,
	Daniel Kiper <daniel.kiper@...cle.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH 3.4 85/88] xen/balloon: Subtract from xen_released_pages the count that is populated.

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

commit 58b7b53a36b0be8081fbfc91aeea24b83c20ca1b upstream.

We did not take into account that xen_released_pages would be
used outside the initial E820 parsing code. As such we would
did not subtract from xen_released_pages the count of pages
that we had populated back (instead we just did a simple
extra_pages = released - populated).

The balloon driver uses xen_released_pages to set the initial
current_pages count.  If this is wrong (too low) then when a new
(higher) target is set, the balloon driver will request too many pages
from Xen."

This fixes errors such as:

(XEN) memory.c:133:d0 Could not allocate order=0 extent: id=0 memflags=0 (51 of 512)
during bootup and
free_memory            : 0

where the free_memory should be 128.

Acked-by: David Vrabel <david.vrabel@...rix.com>
[v1: Per David's review made the git commit better]
Signed-off-by: Daniel Kiper <daniel.kiper@...cle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/xen/setup.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -399,7 +399,8 @@ char * __init xen_memory_setup(void)
 	populated = xen_populate_chunk(map, memmap.nr_entries,
 			max_pfn, &last_pfn, xen_released_pages);
 
-	extra_pages += (xen_released_pages - populated);
+	xen_released_pages -= populated;
+	extra_pages += xen_released_pages;
 
 	if (last_pfn > max_pfn) {
 		max_pfn = min(MAX_DOMAIN_PAGES, last_pfn);


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