From: Martijn Coenen <m...@google.com>

Allows for capturing lmk kill events and
their rationale.

Cc: Android Kernel Team <kernel-t...@android.com>
Cc: Greg KH <gre...@linuxfoundation.org>
Signed-off-by: Martijn Coenen <m...@google.com>
[jstultz: Checkpatch fixups]
Signed-off-by: John Stultz <john.stu...@linaro.org>
---
 drivers/staging/android/lowmemorykiller.c       | 14 +++++++--
 drivers/staging/android/trace/lowmemorykiller.h | 40 +++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 3 deletions(-)
 create mode 100644 drivers/staging/android/trace/lowmemorykiller.h

diff --git a/drivers/staging/android/lowmemorykiller.c 
b/drivers/staging/android/lowmemorykiller.c
index 98abec7..bda0e8a 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -42,6 +42,9 @@
 #include <linux/rcupdate.h>
 #include <linux/notifier.h>
 
+#define CREATE_TRACE_POINTS
+#include "trace/lowmemorykiller.h"
+
 static u32 lowmem_debug_level = 1;
 static short lowmem_adj[6] = {
        0,
@@ -157,6 +160,8 @@ static unsigned long lowmem_scan(struct shrinker *s, struct 
shrink_control *sc)
                             p->comm, p->pid, oom_score_adj, tasksize);
        }
        if (selected) {
+               long cache_size, cache_limit, free;
+
                task_lock(selected);
                send_sig(SIGKILL, selected, 0);
                /*
@@ -167,6 +172,10 @@ static unsigned long lowmem_scan(struct shrinker *s, 
struct shrink_control *sc)
                if (selected->mm)
                        mark_oom_victim(selected);
                task_unlock(selected);
+               cache_size = other_file * (long)(PAGE_SIZE / 1024);
+               cache_limit = minfree * (long)(PAGE_SIZE / 1024);
+               free = other_free * (long)(PAGE_SIZE / 1024);
+               trace_lowmemory_kill(selected, cache_size, cache_limit, free);
                lowmem_print(1, "Killing '%s' (%d), adj %hd,\n"
                                 "   to free %ldkB on behalf of '%s' (%d) 
because\n"
                                 "   cache %ldkB is below limit %ldkB for 
oom_score_adj %hd\n"
@@ -175,10 +184,9 @@ static unsigned long lowmem_scan(struct shrinker *s, 
struct shrink_control *sc)
                             selected_oom_score_adj,
                             selected_tasksize * (long)(PAGE_SIZE / 1024),
                             current->comm, current->pid,
-                            other_file * (long)(PAGE_SIZE / 1024),
-                            minfree * (long)(PAGE_SIZE / 1024),
+                            cache_size, cache_limit,
                             min_score_adj,
-                            other_free * (long)(PAGE_SIZE / 1024));
+                            free);
                lowmem_deathpending_timeout = jiffies + HZ;
                rem += selected_tasksize;
        }
diff --git a/drivers/staging/android/trace/lowmemorykiller.h 
b/drivers/staging/android/trace/lowmemorykiller.h
new file mode 100644
index 0000000..7d01bd4
--- /dev/null
+++ b/drivers/staging/android/trace/lowmemorykiller.h
@@ -0,0 +1,40 @@
+#undef TRACE_SYSTEM
+#define TRACE_INCLUDE_PATH ../../drivers/staging/android/trace
+#define TRACE_SYSTEM lowmemorykiller
+
+#if !defined(_TRACE_LOWMEMORYKILLER_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_LOWMEMORYKILLER_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(lowmemory_kill,
+       TP_PROTO(struct task_struct *killed_task, long cache_size,
+                long cache_limit, long free),
+
+       TP_ARGS(killed_task, cache_size, cache_limit, free),
+
+       TP_STRUCT__entry(
+                       __array(char, comm, TASK_COMM_LEN)
+                       __field(pid_t, pid)
+                       __field(long, pagecache_size)
+                       __field(long, pagecache_limit)
+                       __field(long, free)
+       ),
+
+       TP_fast_assign(
+                       memcpy(__entry->comm, killed_task->comm, TASK_COMM_LEN);
+                       __entry->pid = killed_task->pid;
+                       __entry->pagecache_size = cache_size;
+                       __entry->pagecache_limit = cache_limit;
+                       __entry->free = free;
+       ),
+
+       TP_printk("%s (%d), page cache %ldkB (limit %ldkB), free %ldKb",
+                 __entry->comm, __entry->pid, __entry->pagecache_size,
+                 __entry->pagecache_limit, __entry->free)
+);
+
+#endif /* !defined(_TRACE_LOWMEMORYKILLER_H) || 
defined(TRACE_HEADER_MULTI_READ) */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
1.9.1

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