hugetlb: fix surplus pages accounting

Michal Hocko · torvalds · commit 4704dea36dd9 · 2018-03-09T16:40:01.000-08:00
Dan Rue has noticed that libhugetlbfs test suite fails counter test: # mount_point="/mnt/hugetlb/" # echo 200 > /proc/sys/vm/nr_hugepages # mkdir -p "${mount_point}" # mount -t hugetlbfs hugetlbfs "${mount_point}" # export LD_LIBRARY_PATH=/root/libhugetlbfs/libhugetlbfs-2.20/obj64 # /root/libhugetlbfs/libhugetlbfs-2.20/tests/obj64/counters Starting testcase "/root/libhugetlbfs/libhugetlbfs-2.20/tests/obj64/counters", pid 3319 Base pool size: 0 Clean... FAIL Line 326: Bad HugePages_Total: expected 0, actual 1 The bug was bisected to 0c397da ("mm, hugetlb: further simplify hugetlb allocation API"). The reason is that alloc_surplus_huge_page() misaccounts per node surplus pages. We should increase surplus_huge_pages_node rather than nr_huge_pages_node which is already handled by alloc_fresh_huge_page. Link: http://lkml.kernel.org/r/20180221191439.GM2231@dhcp22.suse.cz Fixes: 0c397da ("mm, hugetlb: further simplify hugetlb allocation API") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Dan Rue <dan.rue@linaro.org> Tested-by: Dan Rue <dan.rue@linaro.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
@@ -1583,7 +1583,7 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
 		page = NULL;
 	} else {
 		h->surplus_huge_pages++;
-		h->nr_huge_pages_node[page_to_nid(page)]++;
+		h->surplus_huge_pages_node[page_to_nid(page)]++;
 	}
 
 out_unlock:

Original file line number	Diff line number	Diff line change
`@@ -1583,7 +1583,7 @@ static struct page alloc_surplus_huge_page(struct hstate h, gfp_t gfp_mask,`
`1583`	`1583`	`page = NULL;`
`1584`	`1584`	`} else {`
`1585`	`1585`	`h->surplus_huge_pages++;`
`1586`		`- h->nr_huge_pages_node[page_to_nid(page)]++;`
	`1586`	`+ h->surplus_huge_pages_node[page_to_nid(page)]++;`
`1587`	`1587`	`}`
`1588`	`1588`
`1589`	`1589`	`out_unlock:`