Qian Cai [off-list ref] writes:

On Thu, 2019-10-31 at 20:39 +1100, Daniel Axtens wrote:

quoted

 	/*
 	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
 	 * flag. It means that vm_struct is not fully initialized.

@@ -3377,6 +3411,9 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
 
 		setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
 				 pcpu_get_vm_areas);
+
+		/* assume success here */
+		kasan_populate_vmalloc(sizes[area], vms[area]);
 	}
 	spin_unlock(&vmap_area_lock);

Here it is all wrong. GFP_KERNEL with in_atomic().

I think this fix will work, I will do a v12 with it included.

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a4b950a02d0b..bf030516258c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c

@@ -3417,11 +3417,14 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
 
                setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
                                 pcpu_get_vm_areas);
+       }
+       spin_unlock(&vmap_area_lock);
 
+       /* populate the shadow space outside of the lock */
+       for (area = 0; area < nr_vms; area++) {
                /* assume success here */
                kasan_populate_vmalloc(sizes[area], vms[area]);
        }
-       spin_unlock(&vmap_area_lock);
 
        kfree(vas);
        return vms;