From: "Stephen C. Tweedie" <sct@dcs.ed.ac.uk>
To: "Eric W. Biederman" <ebiederm+eric@npwt.net>
Cc: linux-mm@kvack.org
Subject: Re: filemap_nopage is broken!!
Date: Thu, 23 Apr 1998 23:01:32 +0100 [thread overview]
Message-ID: <199804232201.XAA02883@dax.dcs.ed.ac.uk> (raw)
In-Reply-To: <m1vhs1oa10.fsf@flinx.npwt.net>
Hi,
On 22 Apr 1998 15:51:07 -0500, ebiederm+eric@npwt.net (Eric
W. Biederman) said:
> Now if the following sequence of actions occure.
> a) A page is mapped privately with poor alignment.
> b) That part of the file is written again.
> c) The page is again mapped privately with poor alignment.
> When the page cache page is not scavenged between a and c, the same
> data is read, despite the fact it has changed on disk, and in the
> aligned page cache page!
> That is broken behavior.
I don't think this is necessarily a problem. The kernel simply does not
guarantee full correspondance semantics between filesystem updates and
the page cache for non-aligned pages, but then again, it is not required
to --- it is not even required to support such mmaps, so I can live with
an undefined behaviour in this case!
--Stephen
next prev parent reply other threads:[~1998-04-24 0:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-04-22 20:51 Eric W. Biederman
1998-04-23 22:01 ` Stephen C. Tweedie [this message]
1998-04-24 0:51 ` Eric W. Biederman
1998-04-24 20:32 ` Stephen C. Tweedie
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