Re: [PATCH] VMI paravirt-ops bugfix for 2.6.21
- From: Andi Kleen <ak@xxxxxxx>
- Date: Sat, 31 Mar 2007 16:35:01 +0200
On Saturday 31 March 2007 10:45, Zachary Amsden wrote:
So lazy MMU mode is vulnerable to interrupts coming in and issuing
kmap_atomic, which does not work when under lazy MMU mode. The window
for this is small, but it means highmem kernels, especially with heavy
network, USB, or AIO workloads are vulnerable to getting invariably
fatal pagefaults in interrupt handlers. For now, the best fix is to
simply disable and re-enable interrupts when entering and exiting lazy
mode (which, btw, is already guaranteed to have preempt disabled). For
the future, a better fix is to simply exit lazy mode when issuing
kmap_atomic, but I do not want to touch any generic code now for 2.6.21.
I think I would prefer you touch the generic code. This new hook is ugly.
And the lazy mode is currently only used by VMI anyways, isn't it? So you shouldn't
impact anybody else
-Andi
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- References:
- [PATCH] VMI paravirt-ops bugfix for 2.6.21
- From: Zachary Amsden
- [PATCH] VMI paravirt-ops bugfix for 2.6.21
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