Re: [PATCH] mm: don't rely on system state to detect hot-plug operations

[Laurent Dufour]

Le 09/09/2020 à 11:24, David Hildenbrand a écrit :
> > > I am not sure an enum is going to make the existing situation less
> > > messy. Sure we somehow have to distinguish boot init and runtime hotplug
> > > because they have different constrains. I am arguing that a) we should
> > > have a consistent way to check for those and b) we shouldn't blow up
> > > easily just because sysfs infrastructure has failed to initialize.
> >
> > For the point a, using the enum allows to know in register_mem_sect_under_node()
> > if the link operation is due to a hotplug operation or done at boot time.
> >
> > For the point b, one option would be ignore the link error in the case the link
> > is already existing, but that BUG_ON() had the benefit to highlight the root issue.
>
> WARN_ON_ONCE() would be preferred  - not crash the system but still
> highlight the issue.

Indeed, calling sysfs_create_link() instead of sysfs_create_link_nowarn() in 
register_mem_sect_under_node() and ignoring EEXIST returned value should do the job.

I'll do that in a separate patch.