Re: ioremap()/iounmap() problem

["Matt Gerassimoff" <mgeras@gmail.com>]

On Mon, 19 Jan 2009 09:13:58 -0700, Russell King - ARM Linux  
<linux@arm.linux.org.uk> wrote:

> diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
> index 18373f7..9f88dd3 100644
> --- a/arch/arm/mm/ioremap.c
> +++ b/arch/arm/mm/ioremap.c
> @@ -138,7 +138,7 @@ void __check_kvm_seq(struct mm_struct *mm)
>   */
>  static void unmap_area_sections(unsigned long virt, unsigned long size)
>  {
> -	unsigned long addr = virt, end = virt + (size & ~SZ_1M);
> +	unsigned long addr = virt, end = virt + (size & ~(SZ_1M - 1));
>  	pgd_t *pgd;
> 	flush_cache_vunmap(addr, end);
> @@ -337,10 +337,7 @@ void __iounmap(volatile void __iomem *io_addr)
>  	void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
>  #ifndef CONFIG_SMP
>  	struct vm_struct **p, *tmp;
> -#endif
> -	unsigned int section_mapping = 0;
> -#ifndef CONFIG_SMP
>  	/*
>  	 * If this is a section based mapping we need to handle it
>  	 * specially as the VM subsystem does not know how to handle
> @@ -352,11 +349,8 @@ void __iounmap(volatile void __iomem *io_addr)
>  	for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
>  		if ((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
>  			if (tmp->flags & VM_ARM_SECTION_MAPPING) {
> -				*p = tmp->next;
>  				unmap_area_sections((unsigned long)tmp->addr,
>  						    tmp->size);
> -				kfree(tmp);
> -				section_mapping = 1;
>  			}
>  			break;
>  		}
> @@ -364,7 +358,6 @@ void __iounmap(volatile void __iomem *io_addr)
>  	write_unlock(&vmlist_lock);
>  #endif
> -	if (!section_mapping)
> -		vunmap(addr);
> +	vunmap(addr);
>  }
>  EXPORT_SYMBOL(__iounmap);

Before this is even tested.  I've went down this path.  You will receive a  
ton
of Bad PMD errors.  unmap_area_sections() and vunmap() don't play nice  
together.
This type of solution will require changes to unmap_area_sections().

-- 
Matt