Re: [PATCH v2 2/7] mm/vmalloc.c: add flags to mark vm_map_ram area

[Lorenzo Stoakes]

On Sat, Dec 17, 2022 at 09:54:30AM +0800, Baoquan He wrote:
> @@ -2229,8 +2236,12 @@ void vm_unmap_ram(const void *mem, unsigned int count)
>  		return;
>  	}
>
> -	va = find_vmap_area(addr);
> +	spin_lock(&vmap_area_lock);
> +	va = __find_vmap_area((unsigned long)addr, &vmap_area_root);
>  	BUG_ON(!va);
> +	if (va)
> +		va->flags &= ~VMAP_RAM;
> +	spin_unlock(&vmap_area_lock);
>  	debug_check_no_locks_freed((void *)va->va_start,
>  				    (va->va_end - va->va_start));
>  	free_unmap_vmap_area(va);

Would it be better to perform the BUG_ON() after the lock is released? You
already check if va exists before unmasking so it's safe.

Also, do we want to clear VMAP_BLOCK here?