Re: [PATCH v3 02/22] x86,mce: Delete ist_begin_non_atomic()

[Andy Lutomirski]

On Wed, Feb 19, 2020 at 9:13 AM Borislav Petkov <bp@xxxxxxxxx> wrote:
>
> On Wed, Feb 19, 2020 at 03:47:26PM +0100, Peter Zijlstra wrote:
> > Subject: Re: [PATCH v3 02/22] x86,mce: Delete ist_begin_non_atomic()
>
> x86/mce: ...
>
> > It is an abomination; and in prepration of removing the whole
> > ist_enter() thing, it needs to go.
> >
> > Convert #MC over to using task_work_add() instead; it will run the
> > same code slightly later, on the return to user path of the same
> > exception.
>
> That's fine because the error happened in userspace.

Unless there is a signal pending and the signal setup code is about to
hit the same failed memory.  I suppose we can just treat cases like
this as "oh well, time to kill the whole system".

But we should genuinely agree that we're okay with deferring this handling.