Re: [HMM v15 01/16] mm/free_hot_cold_page: catch ZONE_DEVICE pages

[Dave Hansen]

On 01/09/2017 01:19 AM, Balbir Singh wrote:
>> +	/*
>> +	 * This should never happen ! Page from ZONE_DEVICE always must have an
>> +	 * active refcount. Complain about it and try to restore the refcount.
>> +	 */
>> +	if (is_zone_device_page(page)) {
>> +		VM_BUG_ON_PAGE(is_zone_device_page(page), page);
> This can be VM_BUG_ON_PAGE(1, page), hopefully the compiler does the right thing
> here. I suspect this should be a BUG_ON, independent of CONFIG_DEBUG_VM

BUG_ON() means "kill the machine dead".  Do we really want a guaranteed
dead machine if someone screws up their refcounting?