Commit dd0c17c6 authored by Michal Hocko's avatar Michal Hocko Committed by Jason Liu

mm: fix off-by-two in __zone_watermark_ok()

Commit 88f5acf8 ("mm: page allocator: adjust the per-cpu counter
threshold when memory is low") changed the form how free_pages is
calculated but it forgot that we used to do free_pages - ((1 << order) -
1) so we ended up with off-by-two when calculating free_pages.
Reported-by: default avatarWang Sheng-Hui <>
Signed-off-by: default avatarMichal Hocko <>
Acked-by: default avatarMel Gorman <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent f7df0060
......@@ -1474,7 +1474,7 @@ static bool __zone_watermark_ok(struct zone *z, int order, unsigned long mark,
long min = mark;
int o;
free_pages -= (1 << order) + 1;
free_pages -= (1 << order) - 1;
if (alloc_flags & ALLOC_HIGH)
min -= min / 2;
if (alloc_flags & ALLOC_HARDER)
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