ITPEC IP October 2025 Question 17

Two or more processes endlessly waiting for each other to release the resources they occupy — that circular wait is a deadlock.

Under exclusive control, a process locks a shared resource while it uses it. Suppose process P has locked resource X and requests Y, while process Q has locked Y and requests X. Each waits for the other's lock, neither can continue, and so neither ever releases what it holds: both wait forever unless the OS or DBMS detects the cycle and aborts one of them.

Answer (c)

Why not others:

• •(a) — keeping processes away from information they must not access is access control (protection), not a waiting state
• •(b) — blocking a user's logins for a set period, or until an administrator resets the account, after too many failed attempts is account lockout
• •(d) — using up the allocated CPU time is the end of a time slice; the process goes back to the ready queue and runs again later, so nothing is stuck

Key rule: A deadlock needs exclusive locks plus a circular wait; having every process lock resources in the same order prevents it.

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