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Subject: Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness
 tracking
References: <cover.1498022414.git.luto@kernel.org>
 <70f3a61658aa7c1c89f4db6a4f81d8df9e396ade.1498022414.git.luto@kernel.org>
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Message-ID: <cb8aad11-6e02-bc8e-8613-63f63a22bc77@oracle.com>
Date: Fri, 23 Jun 2017 09:34:42 -0400
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To: Andy Lutomirski <luto@kernel.org>, x86@kernel.org
Cc: linux-kernel@vger.kernel.org, Borislav Petkov <bp@alien8.de>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mgorman@suse.de>, "linux-mm@kvack.org" <linux-mm@kvack.org>, Nadav Amit <nadav.amit@gmail.com>, Rik van Riel <riel@redhat.com>, Dave Hansen <dave.hansen@intel.com>, Arjan van de Ven <arjan@linux.intel.com>, Peter Zijlstra <peterz@infradead.org>, Andrew Banman <abanman@sgi.com>, Mike Travis <travis@sgi.com>, Dimitri Sivanich <sivanich@sgi.com>, Juergen Gross <jgross@suse.com>


> diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
> index 1d7a7213a310..f5df56fb8b5c 100644
> --- a/arch/x86/xen/mmu_pv.c
> +++ b/arch/x86/xen/mmu_pv.c
> @@ -1005,8 +1005,7 @@ static void xen_drop_mm_ref(struct mm_struct *mm)
>   	/* Get the "official" set of cpus referring to our pagetable. */
>   	if (!alloc_cpumask_var(&mask, GFP_ATOMIC)) {
>   		for_each_online_cpu(cpu) {
> -			if (!cpumask_test_cpu(cpu, mm_cpumask(mm))
> -			    && per_cpu(xen_current_cr3, cpu) != __pa(mm->pgd))
> +			if (per_cpu(xen_current_cr3, cpu) != __pa(mm->pgd))
>   				continue;
>   			smp_call_function_single(cpu, drop_mm_ref_this_cpu, mm, 1);
>   		}
> 


I wonder then whether
	cpumask_copy(mask, mm_cpumask(mm));
immediately below is needed.

-boris

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