Why new kernel thread named lru-add-drain introduced in Red Hat Enterprise Linux 6.10 and Red Hat Enterprise Linux 7.5?

Issue

• Why new kernel thread named lru-add-drain introduced in Red Hat Enterprise Linux 6.10 and Red Hat Enterprise Linux 7.5?
• In Red Hat Enterprise Linux 6.10 :

# ps aux|grep lru
root        72  0.0  0.0      0     0 ?        S    17:37   0:00 [lru-add-drain/0]
root        73  0.0  0.0      0     0 ?        S    17:37   0:00 [lru-add-drain/1]
root        74  0.0  0.0      0     0 ?        S    17:37   0:00 [lru-add-drain/2]
root        75  0.0  0.0      0     0 ?        S    17:37   0:00 [lru-add-drain/3]

• In Red Hat Enterprise Linux 7.5 :

$ ps aux |grep lru
root        10  0.0  0.0      0     0 ?        S<   Jan04   0:00 [lru-add-drain]