[linux-mm-cc] Compcache On Arm 32 bit

[Nitin Gupta]

Hi Vijayendra,

> The problem is even though i am able to see the swap in action but when i
> see the page pte_present flag it is still is one which means it is present
> in the memory, so is it that the RAM block device is not setting this bit as
> 0 when the page is swapped.
>

RAM block device is not responsible for clearing this bit. When
ramzswap_make_request()
begins for a write request, the pte_present flag in corresponding PTE
should have
already been cleared by try_to_unuse().

However, if a swap-in is triggered while swap-out is in process, the page
fault handler will map the corresponding PTE to page being swapped out
(and hence
set pte_present). So, even after swap-out (compression in our case) is
completed,
the PTE can still have pte_present set.