[Linaro-mm-sig] Re: [PATCH 3/9] mm/cma: Allow dynamically creating CMA areas

...

+>> +struct cma *__init cma_create(phys_addr_t base, phys_addr_t size,

•                         unsigned int order_per_bit, const char *name)
  

+{

•   struct cma *cma;
  

•   int ret;
  

•   ret = cma_check_memory(base, size);
  

•   if (ret < 0)
  

•           return ERR_PTR(ret);
  

•   cma = kzalloc(sizeof(*cma), GFP_KERNEL);
  

•   if (!cma)
  

•           return ERR_PTR(-ENOMEM);
  

•   cma_init_area(cma, name, size, order_per_bit);
  

•   cma->ranges[0].base_pfn = PFN_DOWN(base);
  

•   cma->ranges[0].early_pfn = PFN_DOWN(base);
  

•   cma->ranges[0].count = cma->count;
  

•   cma->nranges = 1;
  

•   cma_activate_area(cma);
  

•   return cma;
  

+}

+void cma_free(struct cma *cma) +{

•   kfree(cma);
  

+}

2.50.0

I agree that supporting dynamic CMA areas would be good. However, by doing it like this, these CMA areas are invisible to the rest of the system. E.g. cma_for_each_area() does not know about them. It seems a bit inconsistent that there will now be some areas that are globally known, and some that are not.

Yeah, I'm not a fan of that.

What is the big problem we are trying to solve here? Why do they have to be dynamic, why do they even have to support freeing?