Re: [Xen-devel] [PATCH v4 1/4] x86/mem_sharing: reorder when pages are unlocked and released

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 03.05.19 at 00:13, <tamas@xxxxxxxxxxxxx> wrote:
> @@ -1002,7 +989,10 @@ static int share_pages(struct domain *sd, gfn_t sgfn, 
> shr_handle_t sh,
>      /* Free the client page */
>      if(test_and_clear_bit(_PGC_allocated, &cpage->count_info))
>          put_page(cpage);
> -    put_page(cpage);
> +
> +    BUG_ON(!put_count);
> +    while ( put_count-- )
> +        put_page_and_type(cpage);

Strictly speaking I think the BUG_ON() should be moved ahead of the
if() in context, so that a problematic put_page() would not get
executed in the first place (even if the system is to die soon after).

Jan



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