From 4e1e953202d45ed5eb024fae9c6e0ce7509b25f0 Mon Sep 17 00:00:00 2001
From: Park Ju Hyung <qkrwngud825@gmail.com>
Date: Mon, 9 Mar 2020 03:22:53 +0900
Subject: [PATCH] simple_lmk: count kills and export to sysfs

Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
---
 drivers/android/simple_lmk.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/android/simple_lmk.c b/drivers/android/simple_lmk.c
index f502eb5da8d78..1ee8817f69946 100644
--- a/drivers/android/simple_lmk.c
+++ b/drivers/android/simple_lmk.c
@@ -13,6 +13,10 @@
 #include <linux/vmpressure.h>
 #include <uapi/linux/sched/types.h>

+/* Needed to prevent Android from thinking there's no LMK and thus rebooting */
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX "lowmemorykiller."
+
 /* The minimum number of pages to free per reclaim */
 #define MIN_FREE_PAGES (CONFIG_ANDROID_SIMPLE_LMK_MINFREE * SZ_1M / PAGE_SIZE)

@@ -26,6 +30,7 @@ struct victim_info {
    struct task_struct *tsk;
    struct mm_struct *mm;
    unsigned long size;
+   int adj_index;
 };

 /* Pulled from the Android framework. Lower adj means higher priority. */
@@ -54,6 +59,9 @@ static int victims_to_kill;
 static atomic_t needs_reclaim = ATOMIC_INIT(0);
 static atomic_t nr_killed = ATOMIC_INIT(0);

+static int lmk_count[ARRAY_SIZE(adjs)];
+module_param_array(lmk_count, int, NULL, S_IRUGO);
+
 static int victim_size_cmp(const void *lhs_ptr, const void *rhs_ptr)
 {
    const struct victim_info *lhs = (typeof(lhs))lhs_ptr;
@@ -85,12 +93,13 @@ static unsigned long get_total_mm_pages(struct mm_struct *mm)
    return pages;
 }

-static unsigned long find_victims(int *vindex, short target_adj_min,
-                 short target_adj_max)
+static unsigned long find_victims(int *vindex, int adj_index)
 {
    unsigned long pages_found = 0;
    int old_vindex = *vindex;
    struct task_struct *tsk;
+   short target_adj_min = adjs[adj_index];
+   short target_adj_max = adjs[adj_index - 1];

    for_each_process(tsk) {
        struct signal_struct *sig;
@@ -122,6 +131,7 @@ static unsigned long find_victims(int *vindex, short target_adj_min,
        victims[*vindex].tsk = vtsk;
        victims[*vindex].mm = vtsk->mm;
        victims[*vindex].size = get_total_mm_pages(vtsk->mm);
+       victims[*vindex].adj_index = adj_index;

        /* Keep track of the number of pages that have been found */
        pages_found += victims[*vindex].size;
@@ -179,7 +189,7 @@ static void scan_and_kill(unsigned long pages_needed)
     */
    read_lock(&tasklist_lock);
    for (i = 1; i < ARRAY_SIZE(adjs); i++) {
-       pages_found += find_victims(&nr_victims, adjs[i], adjs[i - 1]);
+       pages_found += find_victims(&nr_victims, i);
        if (pages_found >= pages_needed || nr_victims == MAX_VICTIMS)
            break;
    }
@@ -219,6 +229,9 @@ static void scan_and_kill(unsigned long pages_needed)
            vtsk->signal->oom_score_adj,
            victim->size << (PAGE_SHIFT - 10));

+       /* Count kills */
+       lmk_count[ARRAY_SIZE(adjs) - victim->adj_index - 1]++;
+
        /* Accelerate the victim's death by forcing the kill signal */
        do_send_sig_info(SIGKILL, SEND_SIG_FORCED, vtsk, true);

@@ -320,7 +333,4 @@ static const struct kernel_param_ops simple_lmk_init_ops = {
    .set = simple_lmk_init_set
 };

-/* Needed to prevent Android from thinking there's no LMK and thus rebooting */
-#undef MODULE_PARAM_PREFIX
-#define MODULE_PARAM_PREFIX "lowmemorykiller."
 module_param_cb(minfree, &simple_lmk_init_ops, NULL, 0200);
--
2.25.1