[PATCH] UBUNTU: SAUCE: Fix revert "mm, memory_hotplug: do not associate hotadded memory to zones until online

[Colin Ian King]

Oh, forgot, this is for ARTFUL, my bad

On 17/04/18 12:58, Colin Ian King wrote:
> ping, Can this be reviewed? Thanks.
> 
> 
> On 04/04/18 09:35, Colin King wrote:
>> From: Colin Ian King <colin.king at canonical.com>
>>
>> BugLink: http://bugs.launchpad.net/bugs/1761104
>>
>> Bug fix #1747069 causes an issue for NVIDIA drivers on ppc64el platforms.
>> According to Will Davis at NVIDIA:
>>
>> "- The original patch 3d79a728f9b2e6ddcce4e02c91c4de1076548a4c changed
>> the call to arch_add_memory in mm/memory_hotplug.c to call with the
>> boolean argument set to true instead of false, and inverted the
>> semantics of that argument in the arch layers.
>>
>> - The revert patch 4fe85d5a7c50f003fe4863a1a87f5d8cc121c75c reverted the
>> semantic change in the arch layers, but didn't revert the change to the
>> arch_add_memory call in mm/memory_hotplug.c"
>>
>> And also:
>>
>> "It looks like the problem here is that the online_type is _MOVABLE but
>> can_online_high_movable(nid=255) is returning false:
>>
>>         if ((zone_idx(zone) > ZONE_NORMAL ||
>>             online_type == MMOP_ONLINE_MOVABLE) &&
>>             !can_online_high_movable(pfn_to_nid(pfn)))
>>
>> This check was removed by upstream commit
>> 57c0a17238e22395428248c53f8e390c051c88b8, and I've verified that if I
>> apply that commit (partially) to the 4.13.0-37.42 tree along with the
>> previous arch_add_memory patch to make the probe work, I can fully online
>> the GPU device memory as expected.
>>
>> Commit 57c0a172.. implies that the can_online_high_movable() checks
>> weren't useful anyway, so in addition to the arch_add_memory fix, does
>> it make sense to revert the pieces of
>> 4fe85d5a7c50f003fe4863a1a87f5d8cc121c75c that added back the
>> can_online_high_movable() check?"
>>
>> This patch fixes the partial backport from bug #1747069, by removing
>> can_online_high_movable and fix the incorrectly set boolean argument
>> to arch_add_memory().
>>
>> I've exercised this fix through the ADT tests for i386, amd64 and
>> ppc64el (in VMs) and observe no regressions.
>>
>> Signed-off-by: Colin Ian King <colin.king at canonical.com>
>> ---
>>  mm/memory_hotplug.c | 31 +------------------------------
>>  1 file changed, 1 insertion(+), 30 deletions(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index a4724e7..c1f9677 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -883,23 +883,6 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
>>  	return 0;
>>  }
>>  
>> -#ifdef CONFIG_MOVABLE_NODE
>> -/*
>> - * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
>> - * normal memory.
>> - */
>> -static bool can_online_high_movable(int nid)
>> -{
>> -	return true;
>> -}
>> -#else /* CONFIG_MOVABLE_NODE */
>> -/* ensure every online node has NORMAL memory */
>> -static bool can_online_high_movable(int nid)
>> -{
>> -	return node_state(nid, N_NORMAL_MEMORY);
>> -}
>> -#endif /* CONFIG_MOVABLE_NODE */
>> -
>>  /* check which state of node_states will be changed when online memory */
>>  static void node_states_check_changes_online(unsigned long nr_pages,
>>  	struct zone *zone, struct memory_notify *arg)
>> @@ -1021,18 +1004,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
>>  	struct memory_notify arg;
>>  	int zone_shift = 0;
>>  
>> -	/*
>> -	 * This doesn't need a lock to do pfn_to_page().
>> -	 * The section can't be removed here because of the
>> -	 * memory_block->state_mutex.
>> -	 */
>> -	zone = page_zone(pfn_to_page(pfn));
>> -
>> -	if ((zone_idx(zone) > ZONE_NORMAL ||
>> -	    online_type == MMOP_ONLINE_MOVABLE) &&
>> -	    !can_online_high_movable(pfn_to_nid(pfn)))
>> -		return -EINVAL;
>> -
>>  	if (online_type == MMOP_ONLINE_KERNEL) {
>>  		if (!zone_can_shift(pfn, nr_pages, ZONE_NORMAL, &zone_shift))
>>  			return -EINVAL;
>> @@ -1323,7 +1294,7 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
>>  	}
>>  
>>  	/* call arch's memory hotadd */
>> -	ret = arch_add_memory(nid, start, size, true);
>> +	ret = arch_add_memory(nid, start, size, false);
>>  
>>  	if (ret < 0)
>>  		goto error;
>>
>