the magic in do_page_fault() ???

["liyu@WAN" <liyu@ccoss.com.cn>]

Hi LKML:

    I am reading code of memory management. this process is so challengable.

    I have one quetion too.

    in do_page_fault() (kernel 2.6.11.11) include one piece of code as
follow:


        if (!down_read_trylock(&mm->mmap_sem)) {
        if ((error_code & 4) == 0 &&
            !search_exception_tables(regs->eip))
            goto bad_area_nosemaphore;
        down_read(&mm->mmap_sem);
    }


    I think I can understand these operations on mm->mmap_sem and
"error_code&4".
but how "search_exception_tables(regs->eip)" work here?

    In "Understanding Linux kernel 2ed" book,  the author say , kernel
must difference two case:

      1. kernel memory access problem.
      2. Arguments of system call include address of memeory unit is
unmapped.

    Well, That is OK. but I want to know what 's mechanism in it ?

    3ks. (in Chinese , number 3 read as 'th' :)


                                                             liyu
                                                                Mon Jul
4 13:23:24 CST 2005