lmkd: Introduce kill strategy based on direct reclaim length

Add kill reason for when the device is stuck in direct reclaim for
longer than the configurable threshold. Only allow configurable
threshold, and direct reclaim stuck detection, if memevents direct
reclaim monitoring is enabled.

Test: Verified direct reclaim stuck kill log with memory pressure test
Test: m
Bug: 244232958
Change-Id: I1156899874d2eb7e0f4b61597741087c110b3414
Signed-off-by: Carlos Galo <carlosgalo@google.com>

README.md

@@ -92,6 +92,9 @@ properties:
                                  cycle after kill used to allow blocking of killing
                                  critical processes when not enough memory was freed
                                  in a kill cycle. Default score = 0.
+  - `ro.lmk.direct_reclaim_threshold_ms`: direct reclaim duration threshold in
+                                 milliseconds to consider the system as stuck in
+                                 direct reclaim. Default = 0 (disabled)
 
 lmkd will set the following Android properties according to current system
 configurations:

lmkd.cpp

@@ -40,7 +40,6 @@
 #include <shared_mutex>
 #include <vector>
 
-#include <bpf/KernelUtils.h>
 #include <bpf/WaitForProgsLoaded.h>
 #include <cutils/properties.h>
 #include <cutils/sockets.h>
@@ -161,6 +160,8 @@ static inline void trace_kill_end() {}
 #define DEF_PARTIAL_STALL 70
 /* ro.lmk.psi_complete_stall_ms property defaults */
 #define DEF_COMPLETE_STALL 700
+/* ro.lmk.direct_reclaim_threshold_ms property defaults */
+#define DEF_DIRECT_RECL_THRESH_MS 0
 
 #define LMKD_REINIT_PROP "lmkd.reinit"
 
@@ -228,6 +229,7 @@ static int64_t stall_limit_critical;
 static bool use_psi_monitors = false;
 static int kpoll_fd;
 static bool delay_monitors_until_boot;
+static int direct_reclaim_threshold_ms;
 static struct psi_threshold psi_thresholds[VMPRESS_LEVEL_COUNT] = {
     { PSI_SOME, 70 },    /* 70ms out of 1sec for partial stall */
     { PSI_SOME, 100 },   /* 100ms out of 1sec for partial stall */
@@ -2631,6 +2633,7 @@ static void mp_event_psi(int data, uint32_t events, struct polling_params *poll_
     int64_t workingset_refault_file;
     bool critical_stall = false;
     bool in_direct_reclaim;
+    long direct_reclaim_duration_ms;
 
     if (clock_gettime(CLOCK_MONOTONIC_COARSE, &curr_tm) != 0) {
         ALOGE("Failed to get current time");
@@ -2692,6 +2695,7 @@ static void mp_event_psi(int data, uint32_t events, struct polling_params *poll_
         init_pgscan_direct = vs.field.pgscan_direct;
         init_pgscan_kswapd = vs.field.pgscan_kswapd;
         init_pgrefill = vs.field.pgrefill;
+        direct_reclaim_duration_ms = get_time_diff_ms(&direct_reclaim_start_tm, &curr_tm);
         reclaim = DIRECT_RECLAIM;
     } else if (vs.field.pgscan_kswapd != init_pgscan_kswapd) {
         init_pgscan_kswapd = vs.field.pgscan_kswapd;
@@ -2849,6 +2853,12 @@ static void mp_event_psi(int data, uint32_t events, struct polling_params *poll_
             min_score_adj = PERCEPTIBLE_APP_ADJ + 1;
         }
         check_filecache = true;
+    } else if (reclaim == DIRECT_RECLAIM && direct_reclaim_threshold_ms > 0 &&
+               direct_reclaim_duration_ms > direct_reclaim_threshold_ms) {
+        kill_reason = DIRECT_RECL_STUCK;
+        snprintf(kill_desc, sizeof(kill_desc),
+                 "device is stuck in direct reclaim (%" PRId64 "ms > %dms)",
+                 direct_reclaim_duration_ms, direct_reclaim_threshold_ms);
     } else if (check_filecache) {
         int64_t file_lru_kb = (vs.field.nr_inactive_file + vs.field.nr_active_file) * page_k;
 
@@ -3499,6 +3509,10 @@ static bool init_monitors() {
         ALOGI("Using memevents for direct reclaim detection");
     } else {
         ALOGI("Using vmstats for direct reclaim detection");
+        if (direct_reclaim_threshold_ms > 0) {
+            ALOGW("Kernel support for direct_reclaim_threshold_ms is not found");
+            direct_reclaim_threshold_ms = 0;
+        }
     }
 
     monitors_initialized = true;
@@ -3916,6 +3930,8 @@ static bool update_props() {
     filecache_min_kb = GET_LMK_PROPERTY(int64, "filecache_min_kb", 0);
     stall_limit_critical = GET_LMK_PROPERTY(int64, "stall_limit_critical", 100);
     delay_monitors_until_boot = GET_LMK_PROPERTY(bool, "delay_monitors_until_boot", false);
+    direct_reclaim_threshold_ms =
+            GET_LMK_PROPERTY(int64, "direct_reclaim_threshold_ms", DEF_DIRECT_RECL_THRESH_MS);
 
     reaper.enable_debug(debug_process_killing);
 

lmkd.rc

@@ -49,3 +49,6 @@ on property:persist.device_config.lmkd_native.swap_util_max=*
 
 on property:persist.device_config.lmkd_native.filecache_min_kb=*
     setprop lmkd.reinit ${sys.boot_completed:-0}
+
+on property:persist.device_config.lmkd_native.direct_reclaim_threshold_ms=*
+    setprop lmkd.reinit ${sys.boot_completed:-0}

statslog.h

@@ -65,6 +65,7 @@ enum kill_reasons {
     LOW_MEM_AND_SWAP_UTIL,
     LOW_FILECACHE_AFTER_THRASHING,
     LOW_MEM,
+    DIRECT_RECL_STUCK,
     KILL_REASON_COUNT
 };