Re: vmalloc comments patch

[Anton Blanchard]

Hi,

> + * To give a safety margin, the linear address starts about 8MB after the end
> + * of physical memory at VMALLOC_START. This is to try and catch memory
> + * overruns.

Thats architecture dependent. On ppc64 for example the kernel text
starts at 0xC000000000000000 and the vmalloc region starts at
0xD000000000000000, 2^60 bits apart.

> +		/* The page table is unlocked because we don't need to traverse
> +		 * the page tables while a page is been allocated. As
> +		 * alloc_page could block for a long time, let go the lock
> +		 */
>  		spin_unlock(&init_mm.page_table_lock);
>  		page = alloc_page(gfp_mask);
>  		spin_lock(&init_mm.page_table_lock);

Since alloc_page can sleep we must drop the spinlock.

Anton