linux-kernel - Re: [RFC, PATCH 13/22] mm, rmap: Free encrypted pages once mapcount drops to zero

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Date:   Mon, 5 Mar 2018 11:13:36 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Tom Lendacky <thomas.lendacky@....com>
Cc:     Kai Huang <kai.huang@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC, PATCH 13/22] mm, rmap: Free encrypted pages once mapcount
 drops to zero

On 03/05/2018 08:26 AM, Kirill A. Shutemov wrote:
> @@ -1292,6 +1308,12 @@ static void page_remove_anon_compound_rmap(struct page *page)
>  		__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr);
>  		deferred_split_huge_page(page);
>  	}
> +
> +	anon_vma = page_anon_vma(page);
> +	if (anon_vma_encrypted(anon_vma)) {
> +		int keyid = anon_vma_keyid(anon_vma);
> +		free_encrypt_page(page, keyid, compound_order(page));
> +	}
>  }

It's not covered in the description and I'm to lazy to dig into it, so:
Without this code, where do they get freed?  Why does it not cause any
problems to free them here?