mm/hugetlb: use EOPNOTSUPP in hugetlb sysctl handlers

Replace ENOTSUPP with EOPNOTSUPP.  If hugepages are not supported, this
value is propagated to userspace.  EOPNOTSUPP is part of uapi and is
widely supported by libc libraries.

It gives nicer message to user, rather than:

  # cat /proc/sys/vm/nr_hugepages
  cat: /proc/sys/vm/nr_hugepages: Unknown error 524

And also LTP's proc01 test was failing because this ret code (524)
was unexpected:

  proc01      1  TFAIL  :  proc01.c:396: read failed: /proc/sys/vm/nr_hugepages: errno=???(524): Unknown error 524
  proc01      2  TFAIL  :  proc01.c:396: read failed: /proc/sys/vm/nr_hugepages_mempolicy: errno=???(524): Unknown error 524
  proc01      3  TFAIL  :  proc01.c:396: read failed: /proc/sys/vm/nr_overcommit_hugepages: errno=???(524): Unknown error 524

Signed-off-by: Jan Stancek <[email protected]>
Acked-by: Naoya Horiguchi <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Acked-by: David Rientjes <[email protected]>
Acked-by: Hillf Danton <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0e27a9db6eb9..aefba5a9cc47 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2751,7 +2751,7 @@ static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
 	int ret;
 
 	if (!hugepages_supported())
-		return -ENOTSUPP;
+		return -EOPNOTSUPP;
 
 	table->data = &tmp;
 	table->maxlen = sizeof(unsigned long);
@@ -2792,7 +2792,7 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write,
 	int ret;
 
 	if (!hugepages_supported())
-		return -ENOTSUPP;
+		return -EOPNOTSUPP;
 
 	tmp = h->nr_overcommit_huge_pages;