NAME. Invalid Memory access: A page fault occurs when a page desired by a user process is not present in memory. For example a missing page can be handled by paging in from a remote source, or write-protecting pages and handling write events. A page fault is also an implicit interrupt generated by MMU but both are NOT same. All hardware components of computer monitor program counter and kernel that are saved in the stack, and CPU registers have to store all current running state information. Some reasons for a page fault are following. Between the exception_enter and exception_exit we call actual page fault handler: __do_page_fault(regs, error_code, address); The __do_page_fault is defined in the same source code file as do_page_fault - arch/x86/mm/fault.c. This ultimately is for improving the behavior of applications/games to avoid hangs and/or invalid access messages … One of the easiest ways to see the number of major and minor page faults on a Linux system is with the ps command. First of all, data abort could happen because of invalid page mapping from kernel space or user space. Our description of exception handling will be a bit sketchy for lack of space. And in the end we return previous context. I wrote a small test-program to pinpoint this more exactly, and it's interesting. Page fault is searched by the operating system, and trace the virtual pages which are needed. And I really mean that "by the CPU" part. Most noticeable single cost? The question you described sound like page demanding for data abort. The userfaultfd feature in the Linux kernel allows userspace to handle page faults and some other memory management tasks. Page fault handling by the CPU. 8.4 Page Fault Exception Handler. -- Logs begin at Wed 2020-01-22 08:45:01 EST, end at Wed 2020-02-26 17:25:39 EST. In particular we won’t be able to cover: The signal codes (see Table 11-8 in Chapter 11 ) … Try the following: ps -eo min_flt,maj_flt,cmd. handle_mm_fault is the sub-routine to fix the page table for user space in linux. ; Assembly programs help to store general registers as well as volatile information. Personally, I don't care much about the speed of the Linux kernel build system, but I do care about the speed with which page faults are handled by the CPU. Example reasons for page fault are as follows. Even if the chances of success are lower, if he is able to succeed in speeding up every page fault on future Intel processors, I would consider that a much greater good. In the beginning of the __do_page_fault we check state of the kmemcheck checker. The memory region descriptors allow the exception handler to perform its job quite efficiently. -- Feb 26 16:28:17 lybica kernel: Linux version 5.5.6-arch1-1 (linux@archlinux) (gcc version 9.2.1 20200130 (Arch Linux 9.2.1+20200130-2)) #1 SMP PREEMPT Mon, 24 Feb 2020 12:20:16 +0000 Feb 26 16:28:17 lybica kernel: Command line: initrd=\initramfs-linux.img initrd=\intel-ucode.img … This will list the current running processes on the system along with the number of minor and major page faults that each process has generated. userfaultfd - create a file descriptor for handling page faults in user space SYNOPSIS #include #include int userfaultfd(int flags); Note: There is no glibc wrapper for this system call; see NOTES. This graceful page fault handling support is on their trek to providing recoverable page fault handling for newer Radeon GPUs with the AMDGPU Linux kernel driver. The kernel VM does really well. Page Fault Handling. As stated previously, the Linux Page Fault exception handler must distinguish exceptions caused by programming errors from those caused by a reference to a page that legitimately belongs to the process address space but simply hasn't been allocated yet..