2GB of Zombie Shared Memory Nobody Reclaimed: Linux IPC Mechanism Selection and Production Troubleshooting Journal
Overview At 1:47 AM, an alert popped up: 192.168.10.23 shared memory usage > 1.5GB. I logged in, ran ipcs -m, and found 14 shared memory segments — 9 of them with nattch=0 (no process attached), yet holding nearly 2GB of physical memory. Worse, ipcrm -m deleted 3 of them, but the rest returned Operation not permitted — the processes had exited a month ago, yet these “zombie segments” refused to leave....