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xen/balloon: fix accounting in alloc_xenballooned_pages error path

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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>
This commit is contained in:
Roger Pau Monne 2020-07-27 11:13:39 +02:00 committed by Juergen Gross
parent 4e722d4fe2
commit 1951fa33ec
1 changed files with 6 additions and 0 deletions
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6
drivers/xen/balloon.c
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@ -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);