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Date:   Tue, 15 May 2018 16:05:49 +0200
From:   Joerg Roedel <joro@8bytes.org>
To:     Toshi Kani <toshi.kani@hpe.com>
Cc:     mhocko@suse.com, akpm@linux-foundation.org, tglx@linutronix.de,
        mingo@redhat.com, hpa@zytor.com, cpandya@codeaurora.org,
        linux-mm@kvack.org, x86@kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [PATCH 2/3] x86/mm: add TLB purge to free pmd/pte page interfaces
Message-ID: <20180515140549.GE18595@8bytes.org>
References: <20180430175925.2657-1-toshi.kani@hpe.com>
 <20180430175925.2657-3-toshi.kani@hpe.com>
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On Mon, Apr 30, 2018 at 11:59:24AM -0600, Toshi Kani wrote:
>  int pud_free_pmd_page(pud_t *pud, unsigned long addr)
>  {
> -	pmd_t *pmd;
> +	pmd_t *pmd, *pmd_sv;
> +	pte_t *pte;
>  	int i;
>  
>  	if (pud_none(*pud))
>  		return 1;
>  
>  	pmd = (pmd_t *)pud_page_vaddr(*pud);
> +	pmd_sv = (pmd_t *)__get_free_page(GFP_KERNEL);

So you need to allocate a page to free a page? It is better to put the
pages into a list with a list_head on the stack.

I am still on favour of just reverting the broken commit and do a
correct and working fix for the/a merge window.


	Joerg