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Solution for hung_task_timeout_secs

Explanation

By default Linux uses up to 40% of the available memory for file system caching. After this mark has been reached the file system flushes all outstanding data to disk causing all following IOs going synchronous. For flushing out this data to disk this there is a time limit of 120 seconds by default. In the case here the IO subsystem is not fast enough to flush the data withing 120 seconds. As IO subsystem responds slowly and more requests are served, System Memory gets filled up resulting in the above error, thus serving HTTP requests.

Testing

I tested this theory with the following:
Change vm.dirty_ratio and vm.dirty_backgroud_ratio

someuser@servercore [/home/someuser]$ sudo sysctl -w vm.dirty_ratio=10
someuser@servercore [/home/someuser]$ sudo sysctl -w vm.dirty_background_ratio=5

Commit Change

someuser@servercore [/home/someuser]# sudo sysctl -p

Make it permanent

When the server seemed more stable and no Kernel/Swap/Memory Panic for a week, I edited /etc/sysctl.conf file to make these permanent after reboot.

someuser@servercore [/home/someuser]$ sudo vi /etc/sysctl.conf

ADD 2 lines at the bottom

vm.dirty_background_ratio = 5
vm.dirty_ratio = 10

Save and exit.

someuser@servercore [/home/someuser]$ sudo reboot

That’s it. I never had this issue .. ever again..

saduran dari https://www.blackmoreops.com/2014/09/22/linux-kernel-panic-issue-fix-hung_task_timeout_secs-blocked-120-seconds-problem/