From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH] xmalloc: make whole pages xfree() clear the
 order field (ab)used by xmalloc()
Date: Mon, 09 Sep 2013 04:14:45 -0700
Message-ID: <CE52FBB5.5D128%keir.xen@gmail.com>
References: <521C75AB02000078000EEA15@nat28.tlf.novell.com>
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To: Jan Beulich <JBeulich@suse.com>, Tomasz Wroblewski <tomasz.wroblewski@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>, dgdegra@tycho.nsa.gov, xen-devel@lists.xenproject.org
List-Id: xen-devel@lists.xenproject.org

On 27/08/2013 08:47, "Jan Beulich" <JBeulich@suse.com> wrote:

> Not doing this was found to cause problems with sequences of allocation
> (multi-page), freeing, and then again allocation of the same page upon
> boot when interrupts are still disabled (causing the owner field to be
> non-zero, thus making the allocator attempt a TLB flush and, in its
> processing, triggering an assertion).
> 
> Reported-by: Tomasz Wroblewski <tomasz.wroblewski@citrix.com>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> Tested-by: Tomasz Wroblewski <tomasz.wroblewski@citrix.com>

Acked-by: Keir Fraser <keir@xen.org>

> --- a/xen/common/xmalloc_tlsf.c
> +++ b/xen/common/xmalloc_tlsf.c
> @@ -629,6 +629,7 @@ void xfree(void *p)
>          unsigned int i, order = get_order_from_pages(size);
>  
>          BUG_ON((unsigned long)p & ((PAGE_SIZE << order) - 1));
> +        PFN_ORDER(virt_to_page(p)) = 0;
>          for ( i = 0; ; ++i )
>          {
>              if ( !(size & (1 << i)) )
> 
> 
>