From: Snild Dolkow <snild.dolkow@xxxxxxxxxxxxxx>
Running multiple instances of LMK is not useful since it will try to
kill the same process.
This patch adds a spinlock to prevent multiple instances of the LMK
running at the same time. Uses spin_trylock and return on failure to
avoid blocking.
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Brian Swetland <swetland@xxxxxxxxxx>
Reviewed-by: Radovan Lekanovic <radovan.lekanovic@xxxxxxxxxxxxxx>
Signed-off-by: Snild Dolkow <snild.dolkow@xxxxxxxxxxxxxx>
Signed-off-by: Oskar Andero <oskar.andero@xxxxxxxxxxxxxx>
---
drivers/staging/android/lowmemorykiller.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index 3b91b0f..0b19353 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -38,6 +38,7 @@
#include <linux/rcupdate.h>
#include <linux/profile.h>
#include <linux/notifier.h>
+#include <linux/spinlock.h>
static uint32_t lowmem_debug_level = 2;
static short lowmem_adj[6] = {
@@ -57,6 +58,8 @@ static int lowmem_minfree_size = 4;
static unsigned long lowmem_deathpending_timeout;
+#define LMK_BUSY (-1)
+
#define lowmem_print(level, x...) \
do { \
if (lowmem_debug_level >= (level)) \
@@ -65,6 +68,7 @@ static unsigned long lowmem_deathpending_timeout;
static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
{
+ static DEFINE_SPINLOCK(lowmem_lock);
struct task_struct *tsk;
struct task_struct *selected = NULL;
int rem = 0;
@@ -104,6 +108,9 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
}
selected_oom_score_adj = min_score_adj;
+ if (spin_trylock(&lowmem_lock) == 0)
+ return LMK_BUSY;
+
rcu_read_lock();
for_each_process(tsk) {
struct task_struct *p;
@@ -120,6 +127,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
time_before_eq(jiffies, lowmem_deathpending_timeout)) {
task_unlock(p);
rcu_read_unlock();
+ spin_unlock(&lowmem_lock);
return 0;
}
oom_score_adj = p->signal->oom_score_adj;
@@ -156,6 +164,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
sc->nr_to_scan, sc->gfp_mask, rem);
rcu_read_unlock();
+ spin_unlock(&lowmem_lock);
return rem;
}
--
1.8.1.5
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