# \[PATCH 6/9\] vdso: Only use MAP\_DROPPABLE when VM\_DROPPABLE exists

- From: Christophe Leroy \<hidden\>
- Date: 2024-08-16 14:37:31 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2024/08/2710858
- Thread: https://ratatoskr.run/linuxppc-dev/2024/08/2710852/t.md

```text
Commit 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always
lazily freeable mappings") only adds MAP_DROPPABLE for 64 bits
architectures, so don't use it on 32 bits as it leads to ENOTSUPP
on mmap().

Signed-off-by: Christophe Leroy <redacted>
---
 lib/vdso/getrandom.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c
index 425a422651de..11ba6dbf3b5e 100644
--- a/lib/vdso/getrandom.c
+++ b/lib/vdso/getrandom.c
@@ -78,7 +78,11 @@ __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_
 
 		params->size_of_opaque_state = sizeof(*state);
 		params->mmap_prot = PROT_READ | PROT_WRITE;
-		params->mmap_flags = MAP_DROPPABLE | MAP_ANONYMOUS;
+		if (IS_ENABLED(CONFIG_64BIT))
+			params->mmap_flags = MAP_DROPPABLE | MAP_ANONYMOUS;
+		else
+			params->mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS;
+
 		for (i = 0; i < ARRAY_SIZE(params->reserved); i++)
 			params->reserved[i] = 0;
 
-- 
2.44.0


```