Page fault handling in Operating Systems - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the cause of a page fault.

Operating Systems

if (error_code & [1]) {
    // Page fault caused by a write operation
}

Drag options to blanks, or click blank then click option'

A0x1

B0x4

C0x2

D0x8

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing the bit for read and write operations.

Using the wrong hexadecimal value for the error code bit.

The error code bit 1 (0x2) indicates if the page fault was caused by a write operation.

2fill in blank

medium

Complete the code to check if the page fault was caused by a protection violation on a present page.

Operating Systems

if (error_code & [1]) {
    // Page present: protection fault
}

Drag options to blanks, or click blank then click option'

A0x1

B0x2

C0x4

D0x8

Attempts:

3 left

💡 Hint

Common Mistakes

Using the bit for write fault instead of page presence.

Misinterpreting the error code bits.

The error code bit 0 (0x1) indicates if the page was present (protection violation).

3fill in blank

hard

Fix the error in the code to correctly handle a page fault caused by user mode access.

Operating Systems

if (error_code & [1]) {
    // Fault caused in user mode
}

Drag options to blanks, or click blank then click option'

A0x4

B0x1

C0x2

D0x8

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing user mode bit with write or present bits.

Using incorrect hexadecimal values.

The error code bit 2 (0x4) indicates if the fault happened in user mode.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps page numbers to their status if the page is present and accessed in user mode.

Operating Systems

page_status = {page_num: status for page_num, status in pages.items() if (status & [1]) and (status & [2])}

Drag options to blanks, or click blank then click option'

A0x1

B0x2

C0x4

D0x8

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up bits for write and user mode.

Using bits that do not represent presence or user mode.

Bit 0 (0x1) checks if the page is present, and bit 2 (0x4) checks if it was accessed in user mode.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps virtual addresses to page numbers for pages that are present, writable, and accessed in user mode.

Operating Systems

virtual_to_page = {va: pa for va, (pa, flags) in memory_map.items() if (flags & [1]) and (flags & [2]) and (flags & [3])}

Drag options to blanks, or click blank then click option'

A0x1

B0x2

C0x4

D0x8

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing write bit with other bits.

Forgetting to check all three conditions.

Bit 0 (0x1) means page present, bit 1 (0x2) means writable, and bit 2 (0x4) means accessed in user mode.