linux-kernel - Re: [RFC PATCH v3 1/2] Add support for eXclusive Page Frame Ownership (XPFO)

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Message-ID: <20161104145040.GA24930@infradead.org>
Date:   Fri, 4 Nov 2016 07:50:40 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Juerg Haefliger <juerg.haefliger@....com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kernel-hardening@...ts.openwall.com, linux-x86_64@...r.kernel.org,
        vpk@...columbia.edu, Tejun Heo <tj@...nel.org>,
        linux-ide@...r.kernel.org
Subject: Re: [RFC PATCH v3 1/2] Add support for eXclusive Page Frame
 Ownership (XPFO)

The libata parts here really need to be split out and the proper list
and maintainer need to be Cc'ed.

> diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
> index 051b6158d1b7..58af734be25d 100644
> --- a/drivers/ata/libata-sff.c
> +++ b/drivers/ata/libata-sff.c
> @@ -715,7 +715,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
>  
>  	DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");
>  
> -	if (PageHighMem(page)) {
> +	if (PageHighMem(page) || xpfo_page_is_unmapped(page)) {
>  		unsigned long flags;
>  
>  		/* FIXME: use a bounce buffer */
> @@ -860,7 +860,7 @@ static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
>  
>  	DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");
>  
> -	if (PageHighMem(page)) {
> +	if (PageHighMem(page) || xpfo_page_is_unmapped(page)) {
>  		unsigned long flags;
>  
>  		/* FIXME: use bounce buffer */
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h

This is just piling one nasty hack on top of another.  libata should
just use the highmem case unconditionally, as it is the correct thing
to do for all cases.