[PATCH 0/1] x86/fpu: math_state_restore() should not blindly disable irqs

Oleg Nesterov
2015-03-05T20:32:41Z

On 03/05, Oleg Nesterov wrote:
>
> And this also means I have another off-topic fix for 4.0/stable, will
> send a patch in a minute...

I knew about this problem, but I didn't realize that restore_sigcontext()
can call a sleeping function after math_state_restore(). So I was going
to fix this later, because we need a lot more cleanups in these paths.

But it turns out, it is trivial to trigger the "BUG: sleeping function
called from invalid context" warning, see the test-case I sent to Dave.

To avoid the confusion, this has nothing to do with the problems we
discuss in other threads, or with the recent changes in tip/x86/fpu.

The patch is horrible, yes. But simple, and math_state_restore/init_fpu
are already horrible and need the cleanups. Hopefully I'll send them "soon".

Oleg.