Re: cma can't activate area on arm64

[Vlastimil Babka <vbabka@suse.cz>]

On 2/22/20 12:42 AM, Jonathan Richardson wrote:
> Hi,
> As of the 5.5 kernel I see boot errors in cma. It reserves 1G and then can't
> activate an area. I added some prints. It's trying to activate the DMA
> zone. This causes a driver to fail allocating a dma pool later on. The
> coherent pool is the default 256MB. If I reduce cma from 1G to 512M
> then it only tries activates DMA32 zone. I assume there was not enough cma
> memory for DMA zone? Are there any configuration changes required due
> to the DMA_ZONE and DMA_ZONE32 changes? I've attached my boot log.

I think this question is better for the ARM guys. CC'd

> [    0.000000] cma: Reserved 1024 MiB at 0x00000000a0000000
> ...
> [    0.390448] Activating cma name: reserved, zone name: DMA
> [    0.396564] pfn = 0xa0000
> [    0.399522] cma->count = 262144
> [    0.406244] pfn failed on = c0000
> [    0.410002] cma: CMA area reserved could not be activated
> 
> static int __init cma_activate_area(struct cma *cma)
> {
>    ...
>     printk("Activating cma name: %s, zone name: %s\n", cma->name, zone->name);
>     printk("pfn = 0x%lx\n", pfn);
>     printk("cma->count = %lu\n", cma->count);
> 
>     do {
>         unsigned j;
> 
>         base_pfn = pfn;
>         for (j = pageblock_nr_pages; j; --j, pfn++) {
>             WARN_ON_ONCE(!pfn_valid(pfn));
>             /*
>              * alloc_contig_range requires the pfn range
>              * specified to be in the same zone. Make this
>              * simple by forcing the entire CMA resv range
>              * to be in the same zone.
>              */
>             if (page_zone(pfn_to_page(pfn)) != zone) {
>                 printk("pfn failed on = 0x%lx\n", pfn);
>                 goto not_in_zone;
>             }
>         }
>         init_cma_reserved_pageblock(pfn_to_page(base_pfn));
>     } while (--i);
> 
> Thanks.
>