low memory killer

[<zhiyuan_zhu@htc.com>]

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hi Johannes

My name is Zhiyuan zhu, an android development engineer in htc.
We encounter a lowmemorykiller’s problem.
Coluld you help to kindly support? Thank you.

Problem describtion:
We noticed that gap of dumping cached value from “lowmemorykiller” and “/proc/meminfo/” are different apparently. Like example below, lowmemorykiller showed cache only has 72460kB while launcher was killed, but /proc/meminfo showed cached still has 142448kB. Please check why the gap of cache value between lowmemorykill and /proc/meminfo are huge.

kernel_e0058_0001_20141107_204711_LC4ABYA00200_htc_a31ul_0.54.999.1.txt at LC4ABYA00200
        6      161030.084144       2014-11-07 21:44:53.304        lowmemorykiller: Killing 'om.htc.launcher' (4486), adj 294,
6      161030.084144       2014-11-07 21:44:53.304           to free 47856kB on behalf of 'kworker/u8:14' (20594) because
6      161030.084144       2014-11-07 21:44:53.304           cache 72460kB is below limit 73728kB for oom_score_adj 235
6      161030.084144       2014-11-07 21:44:53.304           Free memory is 51304kB above reserved
4      161030.084797       2014-11-07 21:44:53.304        MemFree:           55676 kB
4      161030.084797       2014-11-07 21:44:53.304        Buffers:            1240 kB
4      161030.084797       2014-11-07 21:44:53.304        Cached:           142448 kB

Lowmemorykiller calculated cache value is 72460kB, but the /proc/meminfo’s cached is 142448 kB

After checked the code, I found that:
Lowmemorykiller’s memory information is comes from /proc/zoneinfo file’s nr_file_pages
So I want to know how different the /proc/zoneinfo file’s nr_file_pages and /proc/meminfo file’s Cached ?

Thanks
Zhiyuan zhu

MEMORY RESOURCE CONTROLLER
M: Johannes Weiner <hannes@cmpxchg.org>
M: Michal Hocko <mhocko@suse.cz>
M: Balbir Singh <bsingharora@gmail.com>
M: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
L:   cgroups@vger.kernel.org
L:   linux-mm@kvack.org
S:  Maintained
F:  mm/memcontrol.c
F:  mm/page_cgroup.c

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