Re: [PATCH] flush_cache_page while pte valid

Rik van Riel
2002-11-12T14:43:21Z

On Mon, 11 Nov 2002, David S. Miller wrote:
> From: Hugh Dickins <hugh@veritas.com>
> Date: Tue, 12 Nov 2002 06:53:04 +0000 (GMT)
>
> Thanks for shedding light on that; but I'm still wondering if there
> might be data loss if userspace modifies the page in the tiny window
> between correctly positioned flush_cache_page and pte invalidation?
>
> The flush merely writes back the data, a copy-back operation, fully L2
> cache coherent. All cpus will see correct data if an intermittant
> store occurs.

The CPUs will, but the harddisk might not.

We really need to get this right in the swapout path.

regards,

Rik
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