ok, I am sorry maybe I did not ask the question correctly, all I want to know is how mmap works underneath, given an address X how does kernel figure out its a mmaped page ?
-Neo On Thu, Jul 25, 2013 at 10:04 AM, <[email protected]> wrote: > On Thu, 25 Jul 2013 09:14:03 -0700, kernel neophyte said: > > > Could anyone please explain, how mmap works underneath ? when kernel > > traveses pgd->pud->pmd->pte how does it know that a particular page is a > > mmaped page ? is there any special flag ? > > Why would the address mapping hardware even *care* that it's an mmap'ed > page, once the mapping is set up? For that matter, why would most of > the kernel code care? > > Only time an mmap'ed page is any different than any other process page is > while the mmap is actually being set up, modified, or torn down. > > (And in fact, that's part of why getting the varions sync() calls to play > nice with mmap() is so hard - because an mmap'ed file page is just a page. > So noticing that a page got modified and knowing to do stuff like update > the atime and mtime of the backing file is difficult...) > >
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