Re: [Help] : RSS/PSS showing 0 during smaps for Xorg

[PINTU KUMAR <pintu_agarwal@yahoo.com>]

Dear Hugh Dickins,
 
Thank you very much for your reply.
 
>If these are ordinary pages with struct pages, then you could probably
>use a loop of vm_insert_page()s to insert them at mmap time, or a fault
>routine to insert them on fault.  But as I said, I don't know if this
>memory is part of the ordinary page pool or not.
 
You suggestion about using vm_insert_page() instead of remap_pfn_range worked for me and I got the Rss/Pss information for my driver.
But still there is one problem related to page fault. 
If I remove remap_pfn_range then I get a page fault in the beginning. 
I tried to use the same vm_insert_page() during page_fault_handler for each vmf->virtual_address but it did not work.
So for time being I remove the page fault handler from my vm_operations.
But with these my menu screen(LCD screen) is not behaving properly (I get colorful lines on my LCD).
So I need to handle the page fault properly.
 
But I am not sure what is that I need to do inside page fault handler. Do you have any example or references or suggestions?
 
 
>Really, the question has to be, why do you need to see non-0s there?
I want Rss/Pss value to account for how much video memory is used by the driver for the menu-screen,Xorg processes.
 
 
 
Thanks,
Pintu
 

>________________________________
>From: Hugh Dickins <hughd@google.com>
>To: PINTU KUMAR <pintu_agarwal@yahoo.com> 
>Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>; "linux-mm@kvack.org" <linux-mm@kvack.org> 
>Sent: Thursday, 26 January 2012 6:29 AM
>Subject: Re: [Help] : RSS/PSS showing 0 during smaps for Xorg
>
>On Tue, 24 Jan 2012, PINTU KUMAR wrote:
>>  
>> Is there a way to convert our mapped pages to a normal pages. I tried pfn_to_page() but no effect.
>> I mean the page is considered normal only if it is associated with "struct page" right???
>> Is is possible to convert these pages to a normal struct pages so that we can get the Rss/Pss value??
>
>I don't understand why you are so anxious to see non-0 numbers there.
>
>I don't know if the pages you are mapping with remap_pfn_range() are
>ordinary pages in normal memory, and so already have struct pages, or not.
>
>>  
>> Also, the VM_PFNMAP is being set for all dirvers during remap_pfn_range and stills shows Rss/Pss for other drivers.
>
>I'm surprised.  It is possible to set up a private-writable VM_PFNMAP area,
>which can then contain ordinary private copies of the underlying pages,
>and these copies will count to Rss.  But I thought that was very unusual.
>
>You don't mention which drivers these are that use remap_pfn_range yet
>show Rss (and I don't particularly want to spend time researching them).
>
>I can see three or four places in drivers/ where VM_PFNMAP is set,
>perhaps without going through remap_pfn_range(): that seems prone
>to error, I wouldn't recommend going that route.
>
>> Then why it is not shown for our driver?
>> How to avoid remap_pfn_range to not to set VM_PFNMAP for our driver?
>
>If these are ordinary pages with struct pages, then you could probably
>use a loop of vm_insert_page()s to insert them at mmap time, or a fault
>routine to insert them on fault.  But as I said, I don't know if this
>memory is part of the ordinary page pool or not.
>
>Really, the question has to be, why do you need to see non-0s there?
>
>Hugh
>
>