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 > "!is_cow_mapping()". > > 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. Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href