linux-kernel - Re: [PATCH] x86/xen: Free bootmem in free_p2m

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Date:	Wed, 07 Jan 2015 15:23:35 +0100
From:	Juergen Gross <jgross@...e.com>
To:	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	david.vrabel@...rix.com, konrad.wilk@...cle.com
CC:	xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/xen: Free bootmem in free_p2m_page() during early
 boot

On 01/07/2015 03:08 PM, Boris Ostrovsky wrote:
> With recent changes in p2m we now have legitimate cases when
> p2m memory needs to be freed during early boot (i.e. before
> slab is initialized).
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>

Reviewed-by: Juergen Gross <jgross@...e.com>

> ---
>   arch/x86/xen/p2m.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
> index edbc7a6..df8acb4 100644
> --- a/arch/x86/xen/p2m.c
> +++ b/arch/x86/xen/p2m.c
> @@ -167,10 +167,13 @@ static void * __ref alloc_p2m_page(void)
>   	return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
>   }
>
> -/* Only to be called in case of a race for a page just allocated! */
>   static void free_p2m_page(void *p)
>   {
> -	BUG_ON(!slab_is_available());
> +	if (unlikely(!slab_is_available())) {
> +		free_bootmem((unsigned long)p, PAGE_SIZE);
> +		return;
> +	}
> +
>   	free_page((unsigned long)p);
>   }
>
>

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