linux-kernel - [PATCH] mm/hugetlbfs: fix for_each_hstate() loop in init_hugetlbfs

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Message-Id: <a14b944b6e5e207d2f84f43227c98ed1f68290a2.1578072927.git.jstancek@redhat.com>
Date:   Fri,  3 Jan 2020 18:37:18 +0100
From:   Jan Stancek <jstancek@...hat.com>
To:     mike.kravetz@...cle.com, akpm@...ux-foundation.org,
        linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, jstancek@...hat.com
Subject: [PATCH] mm/hugetlbfs: fix for_each_hstate() loop in init_hugetlbfs_fs()

LTP memfd_create04 started failing for some huge page sizes
after v5.4-10135-gc3bfc5dd73c6.

Problem is check introduced to for_each_hstate() loop that should
skip default_hstate_idx. Since it doesn't update 'i' counter, all
subsequent huge page sizes are skipped as well.

Fixes: 8fc312b32b25 ("mm/hugetlbfs: fix error handling when setting up mounts")
Signed-off-by: Jan Stancek <jstancek@...hat.com>
---
 fs/hugetlbfs/inode.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index d5c2a3158610..a66e425884d1 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -1498,8 +1498,10 @@ static int __init init_hugetlbfs_fs(void)
 	/* other hstates are optional */
 	i = 0;
 	for_each_hstate(h) {
-		if (i == default_hstate_idx)
+		if (i == default_hstate_idx) {
+			i++;
 			continue;
+		}
 
 		mnt = mount_one_hugetlbfs(h);
 		if (IS_ERR(mnt))
-- 
1.8.3.1