setting stack limit with ulimit in kernel 5.x

Found a very weird situation.

setting ulimit with ulimit command:

ulimit -s 5100000ulimit -c 1000000ulimit -n 4096

checking ulimit - all good

[lt@lt-hkg1-tsr01 ~]$ ulimit -acore file size          (blocks, -c) 1000000data seg size           (kbytes, -d) unlimitedscheduling priority             (-e) 0file size               (blocks, -f) unlimitedpending signals                 (-i) 255870max locked memory       (kbytes, -l) 64max memory size         (kbytes, -m) unlimitedopen files                      (-n) 4096pipe size            (512 bytes, -p) 8POSIX message queues     (bytes, -q) 819200real-time priority              (-r) 0stack size              (kbytes, -s) 5100000cpu time               (seconds, -t) unlimitedmax user processes              (-u) 4096virtual memory          (kbytes, -v) unlimitedfile locks                      (-x) unlimited[lt@lt-hkg1-tsr01 ~]$ 

now checking ulimit via cgexec

[lt@lt-hkg1-tsr03 ~]$ cgexec -g cpuset:/lt/default /bin/bash -c "ulimit -a"core file size          (blocks, -c) 1000000data seg size           (kbytes, -d) unlimitedscheduling priority             (-e) 0file size               (blocks, -f) unlimitedpending signals                 (-i) 1031435max locked memory       (kbytes, -l) 64max memory size         (kbytes, -m) unlimitedopen files                      (-n) 4096pipe size            (512 bytes, -p) 8POSIX message queues     (bytes, -q) 819200real-time priority              (-r) 0stack size              (kbytes, -s) 8192cpu time               (seconds, -t) unlimitedmax user processes              (-u) 4096virtual memory          (kbytes, -v) unlimitedfile locks                      (-x) unlimited[lt@lt-hkg1-tsr03 ~]$ 

as you can see core files and open files are correctbut stack size reset back to default (even I have a different value in /etc/security/limits.conf)

I found that this is a case in kernel 5.x (5.4 / 5.10 /5.12) but worked as expected in 3.x and 4.x

Is it a bug or feature?