Re: [PATCH v9 11/12] mm/vmalloc: Hugepage vmalloc mappings

[Ding Tianhong]

> +again:
> +	size = PAGE_ALIGN(size);
> +	area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNINITIALIZED |
>  				vm_flags, start, end, node, gfp_mask, caller);
>  	if (!area)
>  		goto fail;
>  
> -	addr = __vmalloc_area_node(area, gfp_mask, prot, node);
> +	addr = __vmalloc_area_node(area, gfp_mask, prot, shift, node);
>  	if (!addr)
> -		return NULL;
> +		goto fail;
>  
>  	/*
>  	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
> @@ -2788,8 +2878,19 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
>  	return addr;
>  
>  fail:
> -	warn_alloc(gfp_mask, NULL,
> +	if (shift > PAGE_SHIFT) {
> +		free_vm_area(area);
> +		shift = PAGE_SHIFT;
> +		align = real_align;
> +		size = real_size;
> +		goto again;
> +	}
> +
Hi, Nicholas:

I met a problem like this:

[   67.103584] ------------[ cut here ]------------
[   67.103884] kernel BUG at vmalloc.c:2892!
[   67.104387] Internal error: Oops - BUG: 0 [#1] SMP
[   67.104942] Process insmod (pid: 1161, stack limit = 0x(____ptrval____))
[   67.105356] CPU: 2 PID: 1161 Comm: insmod Tainted: G           O      4.19.95+ #9
[   67.105702] Hardware name: linux,dummy-virt (DT)
[   67.106006] pstate: a0000005 (NzCv daif -PAN -UAO)
[   67.106285] pc : free_vm_area+0x78/0x80
[   67.106549] lr : free_vm_area+0x58/0x80

it looks like when __vmalloc_area_node failed, the area is already released, and the free_vm_area
will release the vm area again, so trigger the problem.

3405         ret = remove_vm_area(area->addr);
3406         BUG_ON(ret != area);
3407         kfree(area);


Ding
> +	if (!area) {
> +		/* Warn for area allocation, page allocations already warn */
> +		warn_alloc(gfp_mask, NULL,
>  			  "vmalloc: allocation failure: %lu bytes", real_size);
> +	}
>  	return NULL;
>  }
>  
>