Messages in this thread | | | Subject | Re: Remapping pages mapped to userspace (was: [PATCH 10 of 20] ipath - support for userspace apps using core driver) | From | Bryan O'Sullivan <> | Date | Fri, 17 Mar 2006 09:17:28 -0800 |
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On Fri, 2006-03-17 at 17:13 +0000, Hugh Dickins wrote:
> You seem to be asking to "revoke" an mmap:
Yes. We'd like this ability, too.
> Though it looks like subsequent userspace accesses will then go to > do_anonymous_page, giving ZERO_PAGE to read faults or a fresh anon > page to write faults: I think I'd prefer it if pte_none accesses in > a VM_PFNMAP area gave SIGBUS, but unsure if we can change that now.
It would be unfortunate if userspace were spinning on a chip register, waiting for the register to transition from zero to non-zero, and we replaced that mapping with an anonymous page. In that case, userspace could potentially spin forever, having no way to detect the demise of the device.
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