The ulimits in tmux pane are not correct
Solution 1:
All the tmux sessions are forked from the same tmux process, instead of the shell process that is executing tmux. Although I have reopened the tmux session, it is still forked from the old tmux process, which is started before I have changed the /etc/security/limits.conf and already running for a while, and sure the old process's children will use the old configuration.