Re: [PATCH] mm: vmalloc: annotate find_vmap_area_exceed_addr_lock() for lockdep

[Jens Axboe <axboe@kernel.dk>]

On 3/26/24 3:25 PM, Jens Axboe wrote:
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 22aa63f4ef63..26a69fa6809c 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1032,7 +1032,7 @@ find_vmap_area_exceed_addr_lock(unsigned long addr, struct vmap_area **va)
>  	for (i = 0; i < nr_vmap_nodes; i++) {
>  		vn = &vmap_nodes[i];
>  
> -		spin_lock(&vn->busy.lock);
> +		spin_lock_nested(&vn->busy.lock, i);
>  		va_lowest = __find_vmap_area_exceed_addr(addr, &vn->busy.root);
>  		if (va_lowest) {
>  			if (!va_node || va_lowest->va_start < (*va)->va_start) {

Omar said he tested this and ran into lockdep complaining as it only
supports 8 subclasses. So this patch can't work, but that still leaves
the current kernel code buggy...
	
-- 
Jens Axboe