[PATCH v2 1/2] mm: fix mmap errno value when MAP_DROPPABLE is not supported

Anthony Yznaga
2026-04-02T23:59:48Z

On configs where MAP_DROPPABLE is not supported (currently any 32-bit
config except for PPC32), mmap fails with errno set to ENOTSUPP.
However, ENOTSUPP is not a standard error value that userspace knows
about. The acceptable userspace-visible errno to use is EOPNOTSUPP.
checkpatch.pl has a warning to this effect.

Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings")
Cc: <stable@vger.kernel.org>
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
mm/mmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 5754d1c36462..2311ae7c2ff4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -504,7 +504,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
break;
case MAP_DROPPABLE:
if (VM_DROPPABLE == VM_NONE)
- return -ENOTSUPP;
+ return -EOPNOTSUPP;
/*
* A locked or stack area makes no sense to be droppable.
*
--
2.47.3