From: Jeff Dike <jdike@addtoit.com>
To: Blaisorblade <blaisorblade@yahoo.it>
Cc: user-mode-linux-devel@lists.sourceforge.net,
Young Koh <young.koh@gmail.com>
Subject: Re: [uml-devel] a question about sigsetjmp() in copy_from/to_user()
Date: Sat, 1 Oct 2005 21:03:15 -0400 [thread overview]
Message-ID: <20051002010315.GA4778@localhost.localdomain> (raw)
In-Reply-To: <200509291409.28067.blaisorblade@yahoo.it>
On Thu, Sep 29, 2005 at 02:09:27PM +0200, Blaisorblade wrote:
> Again, that page is not bad. There is no page yet for this address, and the
> host won't allocate one for now.
It is bad in the sense that, unless some space is freed on that mount, a
reference to the page will always fault.
> Ok, this makes a bit of sense, even if IMHO it doesn't work, I now see your
> point (but I still insist with what said above).
Explain why it doesn't work.
> However, even a dirtied page could be "bad", if it has been swapped. If
> we're getting a SIGBUS, it meant that it didn't succeed in freeing any
> memory.
No it can't. A swapped page still counts as occupying space in the filesystem.
If a page was successfully allocated, then accesses to it will always succeed,
even if it needs to be swapped in.
> And, frankly, unless the UML ram file is kept on ramfs (which is RAM-only),
> it can be swapped (both for disk-based filesystem and for tmpfs).
> So, I don't think what you suggest could work.
Swapping makes no difference.
Jeff
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next prev parent reply other threads:[~2005-10-02 22:33 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-27 14:06 [uml-devel] a question about sigsetjmp() in copy_from/to_user() Young Koh
2005-09-27 17:28 ` Jeff Dike
2005-09-28 11:59 ` Blaisorblade
2005-09-28 13:47 ` Young Koh
2005-09-28 14:50 ` Jeff Dike
2005-09-28 19:25 ` Young Koh
2005-09-29 12:09 ` Blaisorblade
2005-09-30 15:08 ` Young Koh
2005-09-30 15:44 ` Geert Uytterhoeven
2005-10-02 1:03 ` Jeff Dike [this message]
2005-10-02 10:23 ` Blaisorblade
2005-10-02 18:31 ` Jeff Dike
2005-10-03 18:35 ` Blaisorblade
2005-10-03 20:38 ` Jeff Dike
2005-09-28 16:09 ` Jeff Dike
2005-09-28 17:26 ` Blaisorblade
2005-09-28 18:43 ` Jeff Dike
2005-09-28 8:41 ` Blaisorblade
2005-09-28 14:22 ` Young Koh
2005-09-28 16:43 ` Blaisorblade
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