On 12/2/20 2:50 PM, David Hildenbrand wrote:
> On 30.11.20 04:29, Anshuman Khandual wrote:
>> This introduces memhp_range_allowed() which can be called in various memory
>> hotplug paths to prevalidate the address range which is being added, with
>> the platform. Then memhp_range_allowed() calls memhp_get_pluggable_range()
>> which provides applicable address range depending on whether linear mapping
>> is required or not. For ranges that require linear mapping, it calls a new
>> arch callback arch_get_mappable_range() which the platform can override. So
>> the new callback, in turn provides the platform an opportunity to configure
>> acceptable memory hotplug address ranges in case there are constraints.
>>
>> This mechanism will help prevent platform specific errors deep down during
>> hotplug calls. This drops now redundant check_hotplug_memory_addressable()
>> check in __add_pages().
>>
>
>
> [...]
>
>> /*
>> * Reasonably generic function for adding memory. It is
>> * expected that archs that support memory hotplug will
>> @@ -317,10 +304,6 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
>> if (WARN_ON_ONCE(!params->pgprot.pgprot))
>> return -EINVAL;
>>
>> - err = check_hotplug_memory_addressable(pfn, nr_pages);
>> - if (err)
>> - return err;
>> -
>
> I was wondering if we should add a VM_BUG_ON(!memhp_range_allowed())
> here to make it clearer that callers are expected to check that first.
> Maybe an other places as well (e.g., arch code where we remove the
> original checks)
Makes sense, will add them.
>
> [...]
>
>
>> #endif /* CONFIG_MEMORY_HOTREMOVE */
>> diff --git a/mm/memremap.c b/mm/memremap.c
>> index 16b2fb482da1..26c1825756cc 100644
>> --- a/mm/memremap.c
>> +++ b/mm/memremap.c
>> @@ -185,6 +185,7 @@ static void dev_pagemap_percpu_release(struct percpu_ref *ref)
>> static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
>> int range_id, int nid)
>> {
>> + const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE;
>> struct range *range = &pgmap->ranges[range_id];
>> struct dev_pagemap *conflict_pgmap;
>> int error, is_ram;
>> @@ -230,6 +231,9 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
>> if (error)
>> goto err_pfn_remap;
>>
>> + if (!memhp_range_allowed(range->start, range_len(range), !is_private))
>> + goto err_pfn_remap;
>> +
>> mem_hotplug_begin();
>>
>> /*
>> @@ -243,7 +247,7 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
>> * the CPU, we do want the linear mapping and thus use
>> * arch_add_memory().
>> */
>> - if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
>> + if (is_private) {
>> error = add_pages(nid, PHYS_PFN(range->start),
>> PHYS_PFN(range_len(range)), params);
>> } else {
>>
>
> In general, LGTM.
>
Okay
