[PATCH 5/9] staging: lowmemorykiller: Trace kill events.

[John Stultz]

From: Martijn Coenen <maco@xxxxxxxxxx>

Allows for capturing lmk kill events and
their rationale.

Cc: Android Kernel Team <kernel-team@xxxxxxxxxxx>
Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Martijn Coenen <maco@xxxxxxxxxx>
[jstultz: Checkpatch fixups]
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
 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