[PATCH 4.9 202/240] mm/hugeltb: handle the error case in hugetlb_fix_reserve_counts()

Greg Kroah-Hartman
2021-05-20T11:22:00Z

From: Miaohe Lin <linmiaohe@huawei.com>

[ Upstream commit da56388c4397878a65b74f7fe97760f5aa7d316b ]

A rare out of memory error would prevent removal of the reserve map region
for a page. hugetlb_fix_reserve_counts() handles this rare case to avoid
dangling with incorrect counts. Unfortunately, hugepage_subpool_get_pages
and hugetlb_acct_memory could possibly fail too. We should correctly
handle these cases.

Link: https://lkml.kernel.org/r/20210410072348.20437-5-linmiaohe@huawei.com
Fixes: b5cec28d36f5 ("hugetlbfs: truncate_hugepages() takes a range of pages")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Feilong Lin <linfeilong@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/hugetlb.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e2b5e38e7a4b..9049e8613237 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -586,13 +586,20 @@ void hugetlb_fix_reserve_counts(struct inode *inode)
{
struct hugepage_subpool *spool = subpool_inode(inode);
long rsv_adjust;
+ bool reserved = false;

rsv_adjust = hugepage_subpool_get_pages(spool, 1);
- if (rsv_adjust) {
+ if (rsv_adjust > 0) {
struct hstate *h = hstate_inode(inode);

- hugetlb_acct_memory(h, 1);
+ if (!hugetlb_acct_memory(h, 1))
+ reserved = true;
+ } else if (!rsv_adjust) {
+ reserved = true;
}
+
+ if (!reserved)
+ pr_warn("hugetlb: Huge Page Reserved count may go negative.\n");
}

/*
--
2.30.2