[PATCH] ARM: LPAE: Invalidate the TLB for module addresses during translation fault

[Russell King - ARM Linux]

On Fri, Feb 24, 2012 at 09:58:06AM +0000, Catalin Marinas wrote:
> On Thu, Feb 23, 2012 at 10:13:43PM +0000, Catalin Marinas wrote:
> > On Thu, Feb 23, 2012 at 07:50:03PM +0000, Russell King - ARM Linux wrote:
> > > On Thu, Feb 23, 2012 at 05:59:41PM +0000, Catalin Marinas wrote:
> > > > During the free_pgtables() call all user and modules/pkmap entries are
> > > > removed.
> > > 
> > > Err, no.  free_pgtables() should only ever touch up to TASK_SIZE, which
> > > is the maximum size of userspace.  Moreover, because TASK_SIZE does not
> > > cover an entire pud, free_pgtables() should not be removing the pud
> > > table.
> > 
> > Are you sure? exit_mmap() calls free_pgtables() with ceiling == 0.  If
> > free_pmd_range() is called for a range in the top 1GB of the task
> > address space (which includes modules), it also calls pud_clear()
> > because ceiling is 0.
> 
> BTW, an alternative patch but which needs wider acknowledgement as it
> touches generic code (I can post it to linux-mm):

I think that's the right solution.

> diff --git a/mm/mmap.c b/mm/mmap.c
> index 3f758c7..5e5c8a8 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1866,7 +1866,7 @@ static void unmap_region(struct mm_struct *mm,
>  	unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
>  	vm_unacct_memory(nr_accounted);
>  	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
> -				 next ? next->vm_start : 0);
> +				 next ? next->vm_start : TASK_SIZE);
>  	tlb_finish_mmu(&tlb, start, end);
>  }
>  
> @@ -2241,7 +2241,7 @@ void exit_mmap(struct mm_struct *mm)
>  	end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
>  	vm_unacct_memory(nr_accounted);
>  
> -	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
> +	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, TASK_SIZE);
>  	tlb_finish_mmu(&tlb, 0, end);
>  
>  	/*
> 
> -- 
> Catalin