Re: [Xen-devel] [PATCH 4/5] mm: Don't request scrubbing until dom0 is running

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Aug 29, 2017 at 01:09:16PM -0400, Boris Ostrovsky wrote:
> There is no need to scrub pages freed during dom0 construction
> since heap will be scrubbed once dom0 is ready (by scrub_heap_pages()).
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
> Changes in v2:
> * Removed '#ifdef CONFIG_SCRUB_DEBUG'
> 
>  xen/common/page_alloc.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
> index 3db77c5..6c08983 100644
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -2247,16 +2247,12 @@ void free_domheap_pages(struct page_info *pg, 
> unsigned int order)
>  
>              spin_unlock_recursive(&d->page_alloc_lock);
>  
> -#ifndef CONFIG_SCRUB_DEBUG
>              /*
>               * Normally we expect a domain to clear pages before freeing 
> them,
>               * if it cares about the secrecy of their contents. However, 
> after
>               * a domain has died we assume responsibility for erasure.
>               */
> -            scrub = !!d->is_dying;
> -#else
> -            scrub = true;
> -#endif
> +            scrub = !!d->is_dying | scrub_debug;

Use logical or here please. And the !! for is_dying is not necessary.

Also please expand the comment to say why scrub_debug is also checked.

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