The kernel is getting hung up where lots of tasks are getting stuck waiting on the buffer_head that is being locked by another task running prune_super().

Issue

• The kernel is getting hung up where lots of tasks are getting stuck waiting on the buffer_head that is being locked by another task running prune_super() for reclaiming inodes for page reclaiming.

[ 6962.278739] INFO: task jbd2/loop8-8:17606 blocked for more than 120 seconds.
[ 6962.278801] INFO: task jsivm:17794 blocked for more than 120 seconds.
[ 6962.278823] INFO: task jsivm:17809 blocked for more than 120 seconds.
[ 6962.278841] INFO: task jsivm:17810 blocked for more than 120 seconds.
[ 6962.278936] INFO: task jsivm:17811 blocked for more than 120 seconds.
[ 6962.279009] INFO: task jsivm:17987 blocked for more than 120 seconds.
[ 6962.279023] INFO: task jsivm:18019 blocked for more than 120 seconds.
[ 6962.279068] INFO: task ps:29385 blocked for more than 120 seconds.
[ 6962.279091] INFO: task ps:29468 blocked for more than 120 seconds.
[ 7082.277489] INFO: task jbd2/loop8-8:17606 blocked for more than 120 seconds.

PID: 17811  TASK: ffff9f84d6136300  CPU: 4   COMMAND: "appthread"
 #0 [ffff9f6f88387878] __schedule at ffffffffa4f8899f
 #1 [ffff9f6f88387908] schedule at ffffffffa4f88eb9
 #2 [ffff9f6f88387918] schedule_timeout at ffffffffa4f86991
 #3 [ffff9f6f883879c0] io_schedule_timeout at ffffffffa4f8857d
 #4 [ffff9f6f883879f0] io_schedule at ffffffffa4f88618
 #5 [ffff9f6f88387a00] bit_wait_io at ffffffffa4f86fe1
 #6 [ffff9f6f88387a18] __wait_on_bit_lock at ffffffffa4f86b91
 #7 [ffff9f6f88387a58] out_of_line_wait_on_bit_lock at ffffffffa4f86de1
 #8 [ffff9f6f88387ad0] __lock_buffer at ffffffffa4a86d52
 #9 [ffff9f6f88387ae0] __ext4_get_inode_loc at ffffffffc04b643a [ext4]
    ...

PID: 17813  TASK: ffff9f8c438f9080  CPU: 3   COMMAND: "appthread"
 #0 [ffff9f8e3f2c8e48] crash_nmi_callback at ffffffffa4858567
 #1 [ffff9f8e3f2c8e58] nmi_handle at ffffffffa4f8d93c
 #2 [ffff9f8e3f2c8eb0] do_nmi at ffffffffa4f8db5d
 #3 [ffff9f8e3f2c8ef0] end_repeat_nmi at ffffffffa4f8cd9c
    [exception RIP: prune_super+9]
    RIP: ffffffffa4a50869  RSP: ffff9f70347a3868  RFLAGS: 00200206
    RAX: ffffffffa4a50860  RBX: 0000000000000400  RCX: 0000000000000000
    RDX: 0000000000000000  RSI: ffff9f70347a3998  RDI: ffff9f6fc5fe4bb0
    RBP: ffff9f70347a3868   R8: 0000000000000000   R9: 0000000000000000
    R10: 0000000000000000  R11: fff00000f0000000  R12: 000000000000001d
    R13: 0000000000000000  R14: ffff9f6fc5fe4bb0  R15: ffff9f70347a3998
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0000
--- <NMI exception stack> ---
 #4 [ffff9f70347a3868] prune_super at ffffffffa4a50869
    ...
 #6 [ffff9f70347a3918] do_try_to_free_pages at ffffffffa49d4d8a
 #7 [ffff9f70347a3990] try_to_free_pages at ffffffffa49d4fdc
 #8 [ffff9f70347a3a28] free_more_memory at ffffffffa4a85d5e
 #9 [ffff9f70347a3a60] __getblk at ffffffffa4a870cb
#10 [ffff9f70347a3ac0] __breadahead at ffffffffa4a88b71
#11 [ffff9f70347a3ae0] __ext4_get_inode_loc at ffffffffc04b63fa [ext4]
#12 [ffff9f70347a3b48] ext4_get_inode_loc at ffffffffc04b894d [ext4]
    ...