sosreport is getting hung up. It may be possible that it's reading /proc/timer_list and waiting for the I/O completion on ext4 filesystem

Issue

• sosreport is getting hung up with a backtrace like this:

[Thu Jan 14 14:03:09 2021] INFO: task sosreport:235059 blocked for more than 600 seconds.
[Thu Jan 14 14:03:09 2021] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[Thu Jan 14 14:03:09 2021] sosreport       D ffff98260bc9e7e0     0 235059 209486 0x00000080
[Thu Jan 14 14:03:09 2021] Call Trace:
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe379df0>] ? bit_wait+0x50/0x50
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe37b720>] schedule+0x30/0x96
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe3795ec>] schedule_timeout+0x25c/0x4d0
[Thu Jan 14 14:03:09 2021]  [<ffffffffbdf6bbee>] ? deadline_add_request+0x6e/0x90
[Thu Jan 14 14:03:09 2021]  [<ffffffffbdccaabb>] ? migrate_enable+0xdb/0x210
[Thu Jan 14 14:03:09 2021]  [<ffffffffbdcfaa12>] ? ktime_get_ts64+0x52/0xf0
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe379df0>] ? bit_wait+0x50/0x50
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe37a40d>] io_schedule_timeout+0xad/0x130
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe37a4a8>] io_schedule+0x18/0x20
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe379e01>] bit_wait_io+0x11/0x50
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe379927>] __wait_on_bit+0x67/0x90
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe379df0>] ? bit_wait+0x50/0x50
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe379a91>] out_of_line_wait_on_bit+0x81/0xb0
[Thu Jan 14 14:03:09 2021]  [<ffffffffbdcbab80>] ? wake_bit_function+0x40/0x40
[Thu Jan 14 14:03:09 2021]  [<ffffffffbde7653a>] __wait_on_buffer+0x2a/0x30
[Thu Jan 14 14:03:09 2021]  [<ffffffffc070d89c>] ext4_wait_block_bitmap+0xcc/0xf0 [ext4]
[Thu Jan 14 14:03:09 2021]  [<ffffffffc074e65e>] ext4_mb_init_cache+0x1be/0x7a0 [ext4]
[Thu Jan 14 14:03:09 2021]  [<ffffffffbddc7a52>] ? __lru_cache_add+0xb2/0xf0
[Thu Jan 14 14:03:09 2021]  [<ffffffffbddc838e>] ? lru_cache_add+0xe/0x10
[Thu Jan 14 14:03:09 2021]  [<ffffffffc074ed56>] ext4_mb_init_group+0x116/0x220 [ext4]
[Thu Jan 14 14:03:09 2021]  [<ffffffffc074f327>] ext4_mb_load_buddy+0x327/0x340 [ext4]
[Thu Jan 14 14:03:09 2021]  [<ffffffffc074f537>] ext4_mb_seq_groups_show+0x1f7/0x280 [ext4]
[Thu Jan 14 14:03:09 2021]  [<ffffffffbde6554c>] seq_read+0x29c/0x440
[Thu Jan 14 14:03:09 2021]  [<ffffffffbdeb7ac0>] proc_reg_read+0x40/0x80
[Thu Jan 14 14:03:09 2021]  [<ffffffffbde3b1df>] vfs_read+0x9f/0x170
[Thu Jan 14 14:03:09 2021]  [<ffffffffbde3c04f>] SyS_read+0x7f/0xf0
[Thu Jan 14 14:03:09 2021]  [<ffffffffbe388428>] tracesys+0xa6/0xcc