[PATCH v2 7/7] mm/vmalloc: Stop scanning for compound pages after encountering small pages in vmap

[Wen Jiang]

From: "Barry Song (Xiaomi)" <baohua at kernel.org>

Users typically allocate memory in descending orders, e.g.
8 → 4 → 0. Once an order-0 page is encountered, subsequent
pages are likely to also be order-0, so we stop scanning
for compound pages at that point.

Signed-off-by: Barry Song (Xiaomi) <baohua at kernel.org>
Signed-off-by: Wen Jiang <jiangwen6 at xiaomi.com>
Tested-by: Xueyuan Chen <xueyuan.chen21 at gmail.com>
---
 mm/vmalloc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index b3389c8f1..60579bfbf 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3576,6 +3576,12 @@ static int __vmap_huge(unsigned long addr, unsigned long end,
 			map_addr = addr;
 			idx = i;
 		}
+		/*
+		 * Once small pages are encountered, the remaining pages
+		 * are likely small as well
+		 */
+		if (shift == PAGE_SHIFT)
+			break;
 
 		addr += 1UL << shift;
 		i += 1U << (shift - PAGE_SHIFT);
-- 
2.34.1