[PATCH 6/9] vdso: Only use MAP_DROPPABLE when VM_DROPPABLE exists

[Christophe Leroy]

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 <christophe.le...@csgroup.eu>
---
 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