On RHEL servers, changing the semaphore value fails with a message "setting key "kernel.sem": Numerical result out of range".

Solution Verified - Updated -


  • On RHEL 7.8 and 8.1 servers, setting the value of semaphore parameter SEMMNI beyond 32768 fails with the error message sysctl: setting key "kernel.sem": Numerical result out of range.
# sysctl -w kernel.sem="4096 2048000 32 32769"
sysctl: setting key "kernel.sem": Numerical result out of range
kernel.sem = 4096 2048000 32 32769
  • Anything up to and including 32768 succeeds :
# sysctl -w kernel.sem="4096 2048000 32 32768"
kernel.sem = 4096 2048000 32 32768
  • This also applies to kernel.msgmni and kernel.shmmni


  • Red Hat Enterprise Linux 7.8
    • starting with kernel version 3.10.0-1127.el7.x86_64
  • Red Hat Enterprise Linux 8.1
    • starting with kernel version 4.18.0-147.el8_1.x86_64
  • Red Hat Enterprise Linux 9

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