From: Hugh Dickins <email@example.com>
To: PINTU KUMAR <firstname.lastname@example.org>
Cc: "email@example.com" <firstname.lastname@example.org>,
Subject: Re: [Help] : RSS/PSS showing 0 during smaps for Xorg
Date: Mon, 23 Jan 2012 11:31:55 -0800 (PST) [thread overview]
Message-ID: <alpine.LSU.email@example.com> (raw)
On Mon, 23 Jan 2012, PINTU KUMAR wrote:
> Dear All,
> I am facing one problem for one of my kernel module for our linux mobile with kernel2.6.36.
> When I do cat /proc/<Xorg pid>/smaps | grep -A 11 /dev/ump , to track information for my ump module,
> we always get Rss/Pss as 0 kB as shown below:
> cat /proc/1731/smaps | grep -A 11 /dev/ump
> 414db000-415ff000 rw-s 00015000 00:12 6803 /dev/ump
> Size: 1168 kB
> Rss: 0 kB
> Pss: 0 kB
> track_rss_value = 0, iswalkcalled = 1, smap_pte_range_called = 1, swap_pte = 0, not_pte_present = 0, not_normal_page = 1
> isspecial = 0, not_special = 1, isMixedMap = 0, pfnpages_null = 0, pfnoff_flag = 0, not_cow_mapping = 1, normal_page_end = 0
> After tracing down the problem, I found out that during "show_smaps" in fs/proc/task_mmu.c and during call to smaps_pte_range the vm_normal_page() is always returning NULL for our /dev/ump driver.
> (smaps_pte_range() is the place where Rss/Pss information is populated)
> Thus mss->resident (Rss value) is never getting incremented.
> To trace the problem I added few flags during show_smaps & vm_normal_page() as shown above. The value of 1 indicates that the condition is executed.
> Thus "normal_page_end" indicates that the "vm_normal_page" has never ended successfully and always returns from
> So, I wanted to know the main cause for vm_normal_page() always returning NULL page for our ump driver.
> What is that I am missing in my driver ?
> Can anyone please let me know what could be the problem in our driver.
This not evidence of any problem in your driver.
vm_normal_page() returns NULL because the pages mapped by your driver
are not normal faultable and reclaimable pages, but an area of physical
memory mapped in by remap_pfn_range(), which sets the VM_PFNMAP flag.
The mm subsystem does not count such pages towards rss (or pss),
hence your 0s.
next prev parent reply other threads:[~2012-01-23 19:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1327310360.96918.YahooMailNeo@web162003.mail.bf1.yahoo.com>
2012-01-23 10:15 ` [Help] : RSS/PSS showing 0 during smaps for Xorg PINTU KUMAR
2012-01-23 19:31 ` Hugh Dickins [this message]
2012-01-25 5:22 ` PINTU KUMAR
2012-01-26 0:59 ` Hugh Dickins
2012-01-30 8:42 ` PINTU KUMAR
2012-01-30 18:49 ` Hugh Dickins
2012-02-01 14:49 ` PINTU KUMAR
2012-02-02 5:20 ` Hugh Dickins
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