Processes block for long periods when trying to read `/proc/$PID/cmdline` under heavy load on RHEL6
Issue
- The server crashed unexpectedly
- When disk load becomes very high processes may block trying to read the contents of a
/proc/$PID/cmdlinefile.- This can cripple use of management tools such as "top", "ps", etc.
Environment
- Red Hat Enterprise Linux 6
- It is currently suspected that only kernels later than 2.6.32-220.el6 are affected.
- Issue reported on kernels 2.6.32-279.el6, 2.6.32-358.6.2.el6 and 2.6.32-431.53.2 so far.
- Issue my be triggered by monitoring software such as HP health (cmahostd), or any tool that reads
/proc/<pid>/cmdline.
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