Linux-UNIX S-TAP 12.1.3.0_r122091_1 and 12.2.1.0_r122289 might cause kernel memory leaks

A defect in these S‑TAP versions can trigger a kernel memory leak in environments with a large number of concurrent or frequently terminating database sessions.  When sessions close, memory allocated for session‑tracking may not be released as expected.  Over time, the unreleased memory accumulates, leading to: 

• Increased kernel memory consumption
• Potential unexpected system reboots once kernel memory is exhausted. 

This condition is workload‑dependent and is most visible in high‑volume database environments.

Remediation 

Resolution 

Install the corrected S‑TAP versions as soon as they become available:

• Version 12.2.1 – Linux-Unix STAP 12.2.1.1_r123268 (see release note)
• Version 12.1 – All Unix/Linux OS: ETA 31 March 2026

Important post‑upgrade requirement


Installing the updated S‑TAP will stop all new memory leaks, but it will not release memory that was already leaked under the affected versions. Therefore, IBM strongly recommends rebooting the server after upgrading to ensure all previously leaked and unrecoverable kernel memory is cleared. A full reboot is required at your earliest convenience to return the system to a known‑good state. 

Workaround (if immediate upgrade is not possible)

If the fixed S‑TAP version cannot be applied immediately:

1. Remove the Inspection Engine (IE). 

   Disabling IE prevents further leaking by stopping new kernel memory. allocations.
2. Reboot the server. 

   K-TAP memory resides in kernel space; only a reboot can free memory that has already leaked. This combination halts the active leak and stabilizes the system until the fixed build is installed.