android/lowmemorykiller: Wait for memory to be freed

The memory reclaim code needs to give time to the system to
return the memory from a killed process otherwise the memory
reclaim code could run continuously, in multiple threads,
which could starve both the watchdog thread and the thread
which is responsible for returning the memory from the
killed process.

Change-Id: Ieded4bfe038ca936247fa4b638070e979b02eaa1
CRs-fixed: 447740
Signed-off-by: Liam Mark <lmark@codeaurora.org>
android/lowmemorykiller: Ignore tasks with freed mm

A killed task can stay in the task list long after its
memory has been returned to the system, therefore
ignore any tasks whose mm struct has been freed.

Change-Id: I76394b203b4ab2312437c839976f0ecb7b6dde4e
CRs-fixed: 450383
Signed-off-by: Liam Mark <lmark@codeaurora.org>
android: lowmemorykiller: add lmk parameters tunning code.

There are cases that LMK doesn't run, even when it must run.
It is due to LMK shrinker not considering memory status per zone.
So add LMK parameters(other_free, other_file) tunnig code to
consider target zone of LMK shrinker.

Change-Id: I6f1f8660d5da920a0e3af45a160499965032081d
Git-commit: 22d990a58fc17b3f0155e15eb2dc3efa037bea1c
Git-repo: https://android.googlesource.com/kernel/common/
[ohaugan@codeaurora.org: Fix compilation issues]
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
android/lowmemorykiller: Selectively count free CMA pages

In certain memory configurations there can be a large number of
CMA pages which are not suitable to satisfy certain memory
requests.

This large number of unsuitable pages can cause the
lowmemorykiller to not kill any tasks because the
lowmemorykiller counts all free pages.
In order to ensure the lowmemorykiller properly evaluates the
free memory only count the free CMA pages if they are suitable
for satisfying the memory request.

Change-Id: I7f06d53e2d8cfe7439e5561fe6e5209ce73b1c90
CRs-fixed: 437016
Signed-off-by: Liam Mark <lmark@codeaurora.org>
android/lowmemorykiller: Account for total_swapcache_pages

The lowmemorykiller relies on NR_FILE_PAGES when measureing
the amount of reclaimable memory in the system.
However when swap is enabled swap cache pages are counted
in NR_FILE_PAGES, and swap cache pages aren't as reclaimable
in low memory as file cache pages. Therefore a large swap
cache can result in the lowmemorykiller not running and
an OOM occuring.

In order to ensure the lowmemorykiller properly evaluates the
amount of reclaimable memory don't count the swap cache pages.

Change-Id: I38239283e572f814b277c718eaf6be7f92abacbb
Signed-off-by: Liam Mark <lmark@codeaurora.org>
lowmemorykiller: sysfs node and notifications

Create node "/sys/kernel/mm/lowmem_notify/notify_trigger_active",
on which an userspace application can poll for notification when
the number of free physical memory pages in the system falls below
a set threshold. The threshold is set by the new module parameter
"/sys/module/lowmemorykiller/parameters/notify_trigger".
The threshold should be typically set to be higher than the largest
free pages value in /sys/module/lowmemorykiller/parameters/minfree,
so that notification happens before any processes get killed.

Change-Id: Iccb2d1ff699e34b2c22687997e428eec27787b82
Signed-off-by: Bhargav Gurappadi <bhargavg1@codeaurora.org>
android: lowmemorykiller: notify_trigger_active compatibility

Rename the "/sys/kernel/mm/lowmem_notify/notify_trigger_active" sysfs node
to "/sys/kernel/mm/lowmemorykiller/notify_trigger_active" to present the same
interface used by older kernels.

Change-Id: I49533fa005c965f5a4d6bd2f771e0f7ddfb1a8f3
Signed-off-by: Michael Vines <mvines@codeaurora.org>