From a888fea6bd0a798c9db8693ef66169354bc6b9d3 Mon Sep 17 00:00:00 2001 From: Roger Pau Monne Date: Mon, 27 Jul 2020 11:13:39 +0200 Subject: [PATCH] xen/balloon: fix accounting in alloc_xenballooned_pages error path MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 1951fa33ec259abdf3497bfee7b63e7ddbb1a394 upstream. 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 Reviewed-by: Juergen Gross Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200727091342.52325-2-roger.pau@citrix.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman --- drivers/xen/balloon.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 05f9f5983ee1..e8976b51c42b 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -694,6 +694,12 @@ 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);