Re: [PATCH] mm/balloon: expose per-node balloon pages in node meminfo

[Hao Ge <hao.ge@linux.dev>]

Hi David


On 2026/5/8 16:23, David Hildenbrand (Arm) wrote:
> On 5/8/26 03:53, Hao Ge wrote:
>> Commit 835de37603ef ("meminfo: add a per node counter for balloon
>> drivers") added NR_BALLOON_PAGES and exposed it in /proc/meminfo.
>> However, the per-node view at /sys/devices/system/node/nodeX/meminfo
>> was not updated, even though the counter is already tracked per-node.
>>
>> Add it to node_read_meminfo() so users can see balloon usage per
>> NUMA node without having to parse the raw vmstat file.
> Using ballooning with vNUMA is rather rare. But sure, why not.

Yeah, it's indeed not common.

We came across this while analyzing a customer's 16C 32G VM with 2 vNUMA 
nodes and balloon enabled.


>> Signed-off-by: Hao Ge <hao.ge@linux.dev>
>> ---
>>   drivers/base/node.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/node.c b/drivers/base/node.c
>> index d7647d077b66..53f4e51d6d82 100644
>> --- a/drivers/base/node.c
>> +++ b/drivers/base/node.c
>> @@ -513,6 +513,7 @@ static ssize_t node_read_meminfo(struct device *dev,
>>   			     "Node %d Slab:           %8lu kB\n"
>>   			     "Node %d SReclaimable:   %8lu kB\n"
>>   			     "Node %d SUnreclaim:     %8lu kB\n"
>> +			     "Node %d Balloon:        %8lu kB\n"
>>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>   			     "Node %d AnonHugePages:  %8lu kB\n"
>>   			     "Node %d ShmemHugePages: %8lu kB\n"
>> @@ -543,7 +544,8 @@ static ssize_t node_read_meminfo(struct device *dev,
>>   				    node_page_state(pgdat, NR_KERNEL_MISC_RECLAIMABLE)),
>>   			     nid, K(sreclaimable + sunreclaimable),
>>   			     nid, K(sreclaimable),
>> -			     nid, K(sunreclaimable)
>> +			     nid, K(sunreclaimable),
>> +			     nid, K(node_page_state(pgdat, NR_BALLOON_PAGES))
>>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>   			     ,
>>   			     nid, K(node_page_state(pgdat, NR_ANON_THPS)),
>
> Shouldn't it be placed under "Unaccepted:", just like for /proc/meminfo?
>
Good catch, thanks. I overlooked this detail -- will fix in v2.

Thanks

Best Regards

Hao