1 files changed, 8 insertions, 0 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index fd4fed321c89..c6db00b45a30 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -3135,10 +3135,15 @@ pmap_mapdev(pa, size)
 {
 	vm_offset_t va, tmpva, offset;
 	unsigned *pte;
+	int hadvmlock;
 
 	offset = pa & PAGE_MASK;
 	size = roundup(offset + size, PAGE_SIZE);
 
+	hadvmlock = mtx_owned(&vm_mtx);
+	if (!hadvmlock)
+		mtx_lock(&vm_mtx);
+
 	va = kmem_alloc_pageable(kernel_map, size);
 	if (!va)
 		panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
@@ -3153,6 +3158,9 @@ pmap_mapdev(pa, size)
 	}
 	invltlb();
 
+	if (!hadvmlock)
+		mtx_unlock(&vm_mtx);
+
 	return ((void *)(va + offset));
 }