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Scheduler Reliability & Performance Issues

1. Ready Queue Updates Are Not Atomic

  • File: src/kernel/proc/proc.c
  • Relevant Lines: ready_queue_push (line 216) and calls from proc_execute (line 1634)
  • Bug: ready_queue_push assumes exclusive access to ready_queues, but the caller proc_execute enqueues new processes with interrupts still enabled. A timer interrupt can invoke proc_switch while the list is mid-update, letting the scheduler traverse partially linked nodes and corrupt the queue.
  • Fix Idea: Disable interrupts (or introduce a scheduler lock) around the enqueue, mirroring the guarded path in proc_mark_ready.

2. PID Table Never Populated

  • File: src/kernel/proc/proc.c
  • Relevant Lines: procs[] declaration (line 42), proc_find_by_pid (line 33), proc_kill_pid (line 1710)
  • Bug: Newly created processes are not inserted into procs[]. Lookup routines (wait/kill/list) therefore fail to find any task except the kernel, breaking PID-based management and /proc style syscalls.
  • Fix Idea: Assign each allocated process to a free slot in procs[] during creation/exec and clear it on teardown.

3. Process Teardown Leaks Resources

  • File: src/kernel/proc/proc.c
  • Relevant Lines: scheduler_cleanup_process (line 323) vs. proc_free_resources (line 188)
  • Bug: When the scheduler reaps a terminated task it frees stacks and segments but skips proc_file_table_cleanup and proc_release_user_memory. File descriptors stay referenced and VM regions remain registered, leaking handles and physical pages.
  • Fix Idea: Reuse proc_free_resources in scheduler_cleanup_process, or at least call the missing cleanup helpers before freeing the struct.