Re: [RFC kgr on klp 0/9] kGraft on the top of KLP

From: Josh Poimboeuf
Date: Mon May 04 2015 - 11:44:41 EST


On Mon, May 04, 2015 at 02:20:09PM +0200, Jiri Slaby wrote:
> Hello,
>
> this is a patchset which teaches the Kernel Live Patching to be
> consistent when patching with the use of the kGraft approach [1].
> Besides helpers, the set adds support for consistency models,
> implements the kGraft consistency model, and finally allows for
> sending signals to complete the patching process quickly (but still
> safely).
>
> Currently we have only two consistency models:
> * none
> * kGraft
>
> None is the one which was present before the patchset and that one
> indeed guarantees no consistency at all. LEAVE_FUNCTION and
> SWITCH_FUNCTION as was described earlier [2]. kGraft is based on the
> well-known RCU principle and every process is converted to the patched
> world on its own, safely. kGraft is LEAVE_KERNEL and SWITCH_THREAD.

Why do we need multiple consistency models?

What are the advantages of the kGraft model over the kGraft/kpatch
hybrid model [1]?

[1] http://lkml.kernel.org/r/cover.1423499826.git.jpoimboe@xxxxxxxxxx

--
Josh
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