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Greg Kaiser f5b1d14fa8 lmkd: Protect against buffer overflow 
We're passing a 'line' whose backing buffer is PAGE_MAX in size
into memory_stat_parse_line().  We protect overflowing the smaller
LINE_MAX 'key' buffer via some C preprocessing macros to assure
we limit the size.

Test: Local build with LMKD_LOG_STATS set for this file.
Bug: 76220622
Change-Id: I9e50d4270f7099e37a9bfc7fb9b9b95cc7adb086
 		2018-08-07 15:42:19 -07:00
include lmkd: Introduce liblmkd_utils for communicating with lmkd process 2018-03-09 11:18:53 -08:00
tests Merge "lmkd: test: access /sys/module/lowmemorykiller/ as u:r:shell:s0" am: b69cb7071d 2018-04-05 19:45:16 -07:00
Android.bp Fix the stats log in lmkd 2018-05-04 13:40:47 -07:00
OWNERS Add lmkd/OWNERS. 2017-12-08 16:12:58 -08:00
README.md lmkd: Introduce support for legacy kill algorithm that uses minfree levels 2018-04-17 01:42:06 +00:00
liblmkd_utils.c lmkd: Introduce liblmkd_utils for communicating with lmkd process 2018-03-09 11:18:53 -08:00
lmkd.c lmkd: Protect against buffer overflow 2018-08-07 15:42:19 -07:00
lmkd.rc lmkd: limit capability set to minimum 2018-04-16 14:51:56 -07:00
statslog.c Fix the stats log in lmkd 2018-05-03 16:04:27 -07:00
statslog.h Fix the stats log in lmkd 2018-05-03 16:04:27 -07:00

README.md

Android Low Memory Killer Daemon

Introduction

Android Low Memory Killer Daemon (lmkd) is a process monitoring memory state of a running Android system and reacting to high memory pressure by killing the least essential process(es) to keep system performing at acceptable levels.

Background

Historically on Android systems memory monitoring and killing of non-essential processes was handled by a kernel lowmemorykiller driver. Since Linux Kernel 4.12 the lowmemorykiller driver has been removed and instead userspace lmkd daemon performs these tasks.

Android Properties

lmkd can be configured on a particular system using the following Android properties:

ro.config.low_ram: choose between low-memory vs high-performance device. Default = false.

ro.lmk.use_minfree_levels: use free memory and file cache thresholds for making decisions when to kill. This mode works the same way kernel lowmemorykiller driver used to work. Default = false

ro.lmk.low: min oom_adj score for processes eligible to be killed at low vmpressure level. Default = 1001 (disabled)

ro.lmk.medium: min oom_adj score for processes eligible to be killed at medium vmpressure level. Default = 800 (non-essential processes)

ro.lmk.critical: min oom_adj score for processes eligible to be killed at critical vmpressure level. Default = 0 (all processes)

ro.lmk.critical_upgrade: enables upgrade to critical level. Default = false

ro.lmk.upgrade_pressure: max mem_pressure at which level will be upgraded because system is swapping too much. Default = 100 (disabled)

ro.lmk.downgrade_pressure: min mem_pressure at which vmpressure event will be ignored because enough free memory is still available. Default = 100 (disabled)

ro.lmk.kill_heaviest_task: kill heaviest eligible task (best decision) vs. any eligible task (fast decision). Default = false

ro.lmk.kill_timeout_ms: duration in ms after a kill when no additional kill will be done, Default = 0 (disabled)

ro.lmk.debug: enable lmkd debug logs, Default = false