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SubjectRe: [PATCH 2/5] mm/memory_hotplug: Create add/del_device_memory functions
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> index 42d79bcc8aab..d3e52ae71bd9 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -996,6 +996,7 @@ static void hmm_devmem_release(struct device *dev, void *data)
> struct zone *zone;
> struct page *page;
> int nid;
> + bool mapping;
>
> if (percpu_ref_tryget_live(&devmem->ref)) {
> dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
> @@ -1010,12 +1011,15 @@ static void hmm_devmem_release(struct device *dev, void *data)
> zone = page_zone(page);
> nid = zone->zone_pgdat->node_id;
>
> - mem_hotplug_begin();
> if (resource->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY)
> - __remove_pages(zone, start_pfn, npages, NULL);
> + mapping = false;
> else
> - arch_remove_memory(nid, start_pfn << PAGE_SHIFT,
> - npages << PAGE_SHIFT, NULL);
> + mapping = true;
> +
> + mem_hotplug_begin();
> + del_device_memory(nid, start_pfn << PAGE_SHIFT, npages << PAGE_SHIFT,
> + NULL,
> + mapping);
> mem_hotplug_done();
>
> hmm_devmem_radix_release(resource);
> @@ -1026,6 +1030,7 @@ static int hmm_devmem_pages_create(struct hmm_devmem *devmem)
> resource_size_t key, align_start, align_size, align_end;
> struct device *device = devmem->device;
> int ret, nid, is_ram;
> + bool mapping;
>
> align_start = devmem->resource->start & ~(PA_SECTION_SIZE - 1);
> align_size = ALIGN(devmem->resource->start +
> @@ -1084,7 +1089,6 @@ static int hmm_devmem_pages_create(struct hmm_devmem *devmem)
> if (nid < 0)
> nid = numa_mem_id();
>
> - mem_hotplug_begin();
> /*
> * For device private memory we call add_pages() as we only need to
> * allocate and initialize struct page for the device memory. More-
> @@ -1096,20 +1100,17 @@ static int hmm_devmem_pages_create(struct hmm_devmem *devmem)
> * want the linear mapping and thus use arch_add_memory().
> */

Some parts of this comment should be moved into add_device_memory now.
(e.g. we call add_pages() ...)

> if (devmem->pagemap.type == MEMORY_DEVICE_PUBLIC)
> - ret = arch_add_memory(nid, align_start, align_size, NULL,
> - false);
> + mapping = true;
> else
> - ret = add_pages(nid, align_start >> PAGE_SHIFT,
> - align_size >> PAGE_SHIFT, NULL, false);
> - if (ret) {
> - mem_hotplug_done();
> - goto error_add_memory;
> - }
> - move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
> - align_start >> PAGE_SHIFT,
> - align_size >> PAGE_SHIFT, NULL);
> + mapping = false;
> +
> + mem_hotplug_begin();
> + ret = add_device_memory(nid, align_start, align_size, NULL, mapping);
> mem_hotplug_done();
>
> + if (ret)
> + goto error_add_memory;
> +
> /*
> * Initialization of the pages has been deferred until now in order
> * to allow us to do the work while not holding the hotplug lock.
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 33d448314b3f..5874aceb81ac 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1889,4 +1889,45 @@ void remove_memory(int nid, u64 start, u64 size)
> unlock_device_hotplug();
> }
> EXPORT_SYMBOL_GPL(remove_memory);
> +
> +#ifdef CONFIG_ZONE_DEVICE
> +int del_device_memory(int nid, unsigned long start, unsigned long size,
> + struct vmem_altmap *altmap, bool mapping)
> +{
> + int ret;

nit: personally I prefer short parameters last in the list.

> + unsigned long start_pfn = PHYS_PFN(start);
> + unsigned long nr_pages = size >> PAGE_SHIFT;
> + struct zone *zone = page_zone(pfn_to_page(pfn));
> +
> + if (mapping)
> + ret = arch_remove_memory(nid, start, size, altmap);
> + else
> + ret = __remove_pages(zone, start_pfn, nr_pages, altmap);
> +
> + return ret;
> +}
> +#endif
> #endif /* CONFIG_MEMORY_HOTREMOVE */
> +
> +#ifdef CONFIG_ZONE_DEVICE
> +int add_device_memory(int nid, unsigned long start, unsigned long size,
> + struct vmem_altmap *altmap, bool mapping)
> +{
> + int ret;

dito

> + unsigned long start_pfn = PHYS_PFN(start);
> + unsigned long nr_pages = size >> PAGE_SHIFT;
> +
> + if (mapping)
> + ret = arch_add_memory(nid, start, size, altmap, false);
> + else
> + ret = add_pages(nid, start_pfn, nr_pages, altmap, false);
> +
> + if (!ret) {
> + struct zone *zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
> +
> + move_pfn_range_to_zone(zone, start_pfn, nr_pages, altmap);
> + }
> +
> + return ret;
> +}
> +#endif
>

Can you document for both functions that they should be called with the
memory hotplug lock in write?

Apart from that looks good to me.

--

Thanks,

David / dhildenb

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