[PATCH] arm64: pageattr: Explicitly bail out when changing permissions for vmalloc_huge mappings

[Dev Jain]

arm64 uses apply_to_page_range to change permissions for kernel VA mappings,
which does not support changing permissions for leaf mappings. This function
will change permissions until it encounters a leaf mapping, and will bail
out. To avoid this partial change, explicitly disallow changing permissions
for VM_ALLOW_HUGE_VMAP mappings.

Signed-off-by: Dev Jain <dev.jain at arm.com>
---
 arch/arm64/mm/pageattr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 39fd1f7ff02a..8337c88eec69 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -96,7 +96,7 @@ static int change_memory_common(unsigned long addr, int numpages,
 	 * we are operating on does not result in such splitting.
 	 *
 	 * Let's restrict ourselves to mappings created by vmalloc (or vmap).
-	 * Those are guaranteed to consist entirely of page mappings, and
+	 * Disallow VM_ALLOW_HUGE_VMAP vmalloc mappings so that
 	 * splitting is never needed.
 	 *
 	 * So check whether the [addr, addr + size) interval is entirely
@@ -105,7 +105,7 @@ static int change_memory_common(unsigned long addr, int numpages,
 	area = find_vm_area((void *)addr);
 	if (!area ||
 	    end > (unsigned long)kasan_reset_tag(area->addr) + area->size ||
-	    !(area->flags & VM_ALLOC))
+	    ((area->flags & (VM_ALLOC | VM_ALLOW_HUGE_VMAP)) != VM_ALLOC))
 		return -EINVAL;
 
 	if (!numpages)
-- 
2.30.2