linux-kernel - Re: [PATCH] Linux VM workaround for Knights Landing A/D leak

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Date:	Tue, 14 Jun 2016 09:47:41 -0700
From:	Nadav Amit <nadav.amit@...il.com>
To:	Lukasz Anaczkowski <lukasz.anaczkowski@...el.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, ak@...ux.intel.com,
	kirill.shutemov@...ux.intel.com, mhocko@...e.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>, harish.srinivasappa@...el.com,
	lukasz.odzioba@...el.com
Subject: Re: [PATCH] Linux VM workaround for Knights Landing A/D leak


Lukasz Anaczkowski <lukasz.anaczkowski@...el.com> wrote:

> From: Andi Kleen <ak@...ux.intel.com>
> +void fix_pte_leak(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
> +{
Here there should be a call to smp_mb__after_atomic() to synchronize with
switch_mm. I submitted a similar patch, which is still pending (hint).

> +	if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids) {
> +		trace_tlb_flush(TLB_LOCAL_SHOOTDOWN, TLB_FLUSH_ALL);
> +		flush_tlb_others(mm_cpumask(mm), mm, addr,
> +				 addr + PAGE_SIZE);
> +		mb();
> +		set_pte(ptep, __pte(0));
> +	}
> +}

Regards,
Nadav