kmalloc-128 slab is growing up to occupy quite a large portion of the total RAM

Issue

• kmalloc-128 slab is growing up to occupy a large portion of the total RAM.

• Roughly 28.3GB out of 125.6GB total RAM is used for slab.

• Roughly 27.8GB out of 28.3GB slab is used for kmalloc-128 cache.

• How to troubleshoot the significant growth on kmalloc-128 slab?

$ cat proc/meminfo 
MemTotal:       131736352 kB
MemFree:        13380380 kB
MemAvailable:   16028600 kB
Buffers:          201292 kB
Cached:          3083324 kB
    ...
SwapTotal:      16777212 kB
SwapFree:       11797112 kB
    ...
Slab:           29665996 kB
    ...

$ cat proc/slabinfo | awk 'NR<3'; cat proc/slabinfo | awk 'NR>2 {print $0 " " $3*$4/1024/1024 " MB"}' | column -t | sort -k17nr | head -5
slabinfo - version: 2.1
# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata <active_slabs> <num_slabs> <sharedavail>
kmalloc-128                 233359797  233365824  128      32   1    :  tunables  0  0  0  :  slabdata  7292682  7292682  0  28487       MB
radix_tree_node             101745     140588     584      28   4    :  tunables  0  0  0  :  slabdata  5021     5021     0  78.2999     MB
vm_area_struct              174042     176341     216      37   2    :  tunables  0  0  0  :  slabdata  4767     4767     0  36.3251     MB
dentry                      163258     165312     192      42   2    :  tunables  0  0  0  :  slabdata  3936     3936     0  30.2695     MB
iomem_cache-512k            42         56         524288   1    128  :  tunables  0  0  0  :  slabdata  56       56       0  28          MB