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The page fault handler in the operating system will then generally pass a segmentation fault to the offending process, indicating that the access was invalid; this usually results in abnormal termination of the code that made the invalid reference.
Segmentation faults can also occur independently of page faults: illegal access to a valid page is a segmentation fault, but not an invalid page fault, and segmentation faults can occur in the middle of a page (hence no page fault), for example in a buffer overflow that stays within a page but illegally overwrites memory.
If page is invalid then a page-fault trap occurs. Check if the memory reference is a valid reference to a location on secondary memory. If not, the process is terminated (illegal memory access). Otherwise, we have to page in the required page. Schedule disk operation to read the desired page into main memory.
[7] [8] For example, a stack buffer overflow can overwrite the return address of a subroutine with an invalid value, which will cause, e.g., a segmentation fault, when the subroutine returns. However, if an exploit overwrites the return address with a valid value, the code in that address will be executed.
If a program later references the evicted page, another page fault occurs and the page must be read back into RAM. The method the operating system uses to select the page frame to reuse, which is its page replacement algorithm, is important to efficiency. The operating system predicts the page frame least likely to be needed soon, often through ...
The page table lookup may fail, triggering a page fault, for two reasons: The lookup may fail if there is no translation available for the virtual address, meaning that virtual address is invalid. This will typically occur because of a programming error, and the operating system must take some action to deal with the problem.
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