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Subject[PATCH 4/9] staging: lowmemorykiller: Make default lowmemorykiller debug message useful
Date
From: Colin Cross <ccross@android.com>

lowmemorykiller debug messages are inscrutable and mostly useful
for debugging the lowmemorykiller, not explaining why a process
was killed. Make the messages more useful by prefixing them
with "lowmemorykiller: " and explaining in more readable terms
what was killed, who it was killed for, and why it was killed.

The messages now look like:
[ 76.997631] lowmemorykiller: Killing 'droid.gallery3d' (2172), adj 1000,
[ 76.997635] to free 27436kB on behalf of 'kswapd0' (29) because
[ 76.997638] cache 122624kB is below limit 122880kB for oom_score_adj 1000
[ 76.997641] Free memory is -53356kB above reserved

A negative number for free memory above reserved means some of the
reserved memory has been used and is being regenerated by kswapd,
which is likely what called the shrinkers.

Cc: Android Kernel Team <kernel-team@android.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Signed-off-by: Colin Cross <ccross@android.com>
[jstultz: Minor checkpatch tweaks]
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
drivers/staging/android/lowmemorykiller.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index 806643d..98abec7 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -83,6 +83,7 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
int tasksize;
int i;
short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
+ int minfree = 0;
int selected_tasksize = 0;
short selected_oom_score_adj;
int array_size = ARRAY_SIZE(lowmem_adj);
@@ -96,8 +97,8 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
if (lowmem_minfree_size < array_size)
array_size = lowmem_minfree_size;
for (i = 0; i < array_size; i++) {
- if (other_free < lowmem_minfree[i] &&
- other_file < lowmem_minfree[i]) {
+ minfree = lowmem_minfree[i];
+ if (other_free < minfree && other_file < minfree) {
min_score_adj = lowmem_adj[i];
break;
}
@@ -152,8 +153,8 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
selected = p;
selected_tasksize = tasksize;
selected_oom_score_adj = oom_score_adj;
- lowmem_print(2, "select %d (%s), adj %hd, size %d, to kill\n",
- p->pid, p->comm, oom_score_adj, tasksize);
+ lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
+ p->comm, p->pid, oom_score_adj, tasksize);
}
if (selected) {
task_lock(selected);
@@ -166,9 +167,18 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
if (selected->mm)
mark_oom_victim(selected);
task_unlock(selected);
- lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n",
- selected->pid, selected->comm,
- selected_oom_score_adj, selected_tasksize);
+ 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"
+ " Free memory is %ldkB above reserved\n",
+ selected->comm, selected->pid,
+ 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),
+ min_score_adj,
+ other_free * (long)(PAGE_SIZE / 1024));
lowmem_deathpending_timeout = jiffies + HZ;
rem += selected_tasksize;
}
--
1.9.1
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