Re: [uml-devel] a question about sigsetjmp() in copy_from/to_user()

[Jeff Dike <jdike@addtoit.com>]

On Wed, Sep 28, 2005 at 09:47:41AM -0400, Young Koh wrote:
> yes, i think memory can go bad if 1) it cannot be allocated because of
> filesystem full or similar reasons as Jeff described, or 2) it was
> allocated once but could have been swapped.
> 
> in case of 1) it should be more like kernel panic rather than just a
> system call error, i think? because kernel cannot allocate any more
> memory, which kernel is supposed to use.

No, just that page is bad.  Another page could have been dirtied and thus
allocated on the host, and it would be usable.  So, it's not a fatal problem.

> in case of 2) this is a real fault, so, the seg fault handler of UML
> kernel is supposed to load the swapped page and UML kernel proceeds
> normally? (as Blaisorblade described in the other mail, by calling
> handle_page_fault()?)

Yes, this happens in the call from maybe_map.

				Jeff


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