On 09.09.20 14:30, Greg Kroah-Hartman wrote:
On Wed, Sep 09, 2020 at 11:24:24AM +0200, David Hildenbrand wrote:
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.
Many many systems now run with 'panic on warn' enabled, so that wouldn't change much :(
If you can warn, you can properly just print an error message and recover from the problem.
Maybe VM_WARN_ON_ONCE() then to detect this during testing?
(we basically turned WARN_ON_ONCE() useless with 'panic on warn' getting used in production - behaves like BUG_ON and BUG_ON is frowned upon)