Re: [PATCH] mm: vmalloc: Use the vmap_area_lock to protect ne_fit_preload_node

[Uladzislau Rezki]

On Fri, Oct 04, 2019 at 05:37:28PM +0200, Sebastian Andrzej Siewior wrote:
> If you post something that is related to PREEMPT_RT please keep tglx and
> me in Cc.
> 
> On 2019-10-03 11:09:06 [+0200], Daniel Wagner wrote:
> > Replace preempt_enable() and preempt_disable() with the vmap_area_lock
> > spin_lock instead. Calling spin_lock() with preempt disabled is
> > illegal for -rt. Furthermore, enabling preemption inside the
> 
> Looking at it again, I have reasonable doubt that this
> preempt_disable() is needed.
> 
The intention was to preload a current CPU with one extra object in
non-atomic context, thus to use GFP_KERNEL permissive parameters. I.e.
that allows us to avoid any allocation(if we stay on the same CPU)
when we are in atomic context do splitting.

If we have migrate_disable/enable, then, i think preempt_enable/disable
should be replaced by it and not the way how it has been proposed
in the patch.

--
Vlad Rezki