From: "Stephen C. Tweedie" <sct@redhat.com>
To: Timur Tabi <ttabi@interactivesi.com>
Cc: Roman Zippel <roman@augan.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: ioremap_nocache problem?
Date: Fri, 26 Jan 2001 10:39:31 +0000 [thread overview]
Message-ID: <20010126103931.C11607@redhat.com> (raw)
In-Reply-To: <3A6D5D28.C132D416@sangate.com> <20010123165117Z131182-221+34@kanga.kvack.org> <20010123165117Z131182-221+34@kanga.kvack.org> <20010125155345Z131181-221+38@kanga.kvack.org> <3A705802.5C4DD2F2@augan.com> <20010125164707Z131181-222+39@kanga.kvack.org>
In-Reply-To: <20010125164707Z131181-222+39@kanga.kvack.org>; from ttabi@interactivesi.com on Thu, Jan 25, 2001 at 10:49:50AM -0600
Hi,
On Thu, Jan 25, 2001 at 10:49:50AM -0600, Timur Tabi wrote:
>
> > set_bit(PG_reserved, &page->flags);
> > ioremap();
> > ...
> > iounmap();
> > clear_bit(PG_reserved, &page->flags);
>
> The problem with this is that between the ioremap and iounmap, the page is
> reserved. What happens if that page belongs to some disk buffer or user
> process, and some other process tries to free it. Won't that cause a problem?
It depends on how it is being used, but yes, it is likely to --- page
reference counts won't be updated properly on reserved pages, for
example. Why on earth do you want to do ioremap of something like a
page cache page, though? That is _not_ what ioremap is designed for!
--Stephen
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next prev parent reply other threads:[~2001-01-26 10:42 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-23 10:30 ioremap_nocache problem? Mark Mokryn
2001-01-23 16:53 ` Timur Tabi
2001-01-23 18:12 ` Roman Zippel
2001-01-24 0:50 ` David Wragg
2001-01-24 15:14 ` Timur Tabi
[not found] ` <E14LRce-0008FU-00@diver.doc.ic.ac.uk>
2001-01-24 15:39 ` David Wragg
2001-01-23 18:38 ` Timur Tabi
2001-01-24 1:01 ` David Wragg
[not found] ` <20010123165117Z131182-221+34@kanga.kvack.org>
2001-01-25 15:16 ` Stephen C. Tweedie
[not found] ` <200101251556.f0PFuPd01743@mail.redhat.com>
2001-01-26 10:37 ` Stephen C. Tweedie
2001-01-25 15:56 ` Timur Tabi
[not found] ` <20010125155345Z131181-221+38@kanga.kvack.org>
2001-01-25 16:44 ` Roman Zippel
[not found] ` <20010125164707Z131181-222+39@kanga.kvack.org>
2001-01-26 10:39 ` Stephen C. Tweedie [this message]
2001-01-25 16:49 ` Timur Tabi
2001-01-25 17:04 ` Jeff Hartmann
2001-01-25 17:11 ` Timur Tabi
[not found] ` <E14LpvQ-0008Pw-00@mail.valinux.com>
2001-01-25 17:47 ` Jeff Hartmann
[not found] ` <20010125175027Z131219-222+40@kanga.kvack.org>
2001-01-26 10:43 ` Stephen C. Tweedie
2001-01-25 17:53 ` Timur Tabi
2001-01-25 18:13 ` Jeff Hartmann
2001-01-25 18:18 ` Timur Tabi
[not found] ` <E14Lqyt-0003z6-00@mail.valinux.com>
2001-01-25 18:46 ` Jeff Hartmann
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