Index: sys/kern/vfs_bio.c
===================================================================
--- sys/kern/vfs_bio.c	(revision 250750)
+++ sys/kern/vfs_bio.c	(working copy)
@@ -2772,7 +2772,7 @@ inmem(struct vnode * vp, daddr_t blkno)
 		size = vp->v_mount->mnt_stat.f_iosize;
 	off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
 
-	VM_OBJECT_WLOCK(obj);
+	VM_OBJECT_RLOCK(obj);
 	for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
 		m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
 		if (!m)
@@ -2784,11 +2784,11 @@ inmem(struct vnode * vp, daddr_t blkno)
 		    (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
 			goto notinmem;
 	}
-	VM_OBJECT_WUNLOCK(obj);
+	VM_OBJECT_RUNLOCK(obj);
 	return 1;
 
 notinmem:
-	VM_OBJECT_WUNLOCK(obj);
+	VM_OBJECT_RUNLOCK(obj);
 	return (0);
 }