Patch-mainline: v5.9-rc1
Git-commit: 1951fa33ec259abdf3497bfee7b63e7ddbb1a394
References: bsc#1065600
From: Roger Pau Monne <roger.pau@citrix.com>
Date: Mon, 27 Jul 2020 11:13:39 +0200
Subject: [PATCH] xen/balloon: fix accounting in alloc_xenballooned_pages error
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target_unpopulated is incremented with nr_pages at the start of the
function, but the call to free_xenballooned_pages will only subtract
pgno number of pages, and thus the rest need to be subtracted before
returning or else accounting will be skewed.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200727091342.52325-2-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
---
drivers/xen/balloon.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 77c57568e5d7..3cb10ed32557 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -630,6 +630,12 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages)
out_undo:
mutex_unlock(&balloon_mutex);
free_xenballooned_pages(pgno, pages);
+ /*
+ * NB: free_xenballooned_pages will only subtract pgno pages, but since
+ * target_unpopulated is incremented with nr_pages at the start we need
+ * to remove the remaining ones also, or accounting will be screwed.
+ */
+ balloon_stats.target_unpopulated -= nr_pages - pgno;
return ret;
}
EXPORT_SYMBOL(alloc_xenballooned_pages);
--
2.26.2