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Message-ID: <3DBD6AE1.8040403@colorfullife.com>
Date: Mon, 28 Oct 2002 17:50:41 +0100
From: Manfred Spraul <manfred@colorfullife.com>
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To: Matthew Wilcox <willy@debian.org>, "David S. Miller" <davem@redhat.com>,
       linux-kernel@vger.kernel.org, Russell King <rmk@arm.linux.org.uk>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH] shmem missing cache flush
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Is it permitted to call flush_dcache_page() on pages that are not in the 
page cache?
The documentation is ambiguous, it only mentions how archs can handle 
dcache aliases for page cache users.

What about the user space accesses that kmap user space pages directly, 
without copy_*_user?

For example:
- ptrace
- disk transfers that end up calling __bio_kmap() - RAID-5, ide error 
handling.
    Could be from irq context!
- hole handling for O_DIRECT file access.

In all 3 cases, the target could be outside of the page cache.

--
    Manfred

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