limit ion cache size

We often see lost ram is still very high even we close the camera app.
That's because camera's ion memory goes into ion cache after use, not
buddy system. And this cache was not counted in proc/meminfo/memAvailable,
so it can not reflect the true memAvailable in this state. It may affects
some components l(CR) camera or lmkd which need evaluate true memAvailable
in system. Take camera as example, while launching camera, camera app needs
calcuate the available memory then call framework api to kill processes,
without this patch, we will see overkill.

This patch is only for 4.14 & 4.19, on kernel 5.4, ion cache will
be counted in memAvailable, so memAvailable is always trustable.

Change-Id: I4a9678530d387bd8da404d797f7d6e33bd258ac4
Signed-off-by: huangzq2 <huangzq2@motorola.com>
Reviewed-on: https://gerrit.mot.com/1792299
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key
(cherry picked from commit a9acaa732c7fcb5e9ec9eea08bb6bb390c316722)
Reviewed-on: https://gerrit.mot.com/1795665

drivers/staging/android/ion/ion_system_heap.c

@@ -18,6 +18,7 @@
 #include <linux/vmalloc.h>
 #include <linux/sched/types.h>
 #include <linux/sched.h>
+#include <linux/module.h>
 #include <soc/qcom/secure_buffer.h>
 #include "ion_system_heap.h"
 #include "ion.h"
@@ -440,6 +441,23 @@ err:
 	return ret;
 }
 
+/*
+ * Moto huangzq2: limit the system ion cache size.
+ * We often see lost ram is still very high even we close the camera app.
+ * That's because camera's ion memory goes into ion cache after use, not
+ * buddy system. And this cache was not counted in proc/meminfo/memAvailable,
+ * so it can not reflect the true memAvailable in this state. It may affects
+ * some components like camera or lmkd which need evaluate true memAvailable
+ * in system. Take camera as example, while launching camera, camera app needs
+ * calcuate the available memory then call framework api to kill processes,
+ * without this patch, we will see overkill.
+ *
+ * This patch is only for 4.14 & 4.19, on kernel 5.4, ion cache will
+ * be counted in memAvailable, so memAvailable is always trustable.
+ */
+static int max_page_pool_size = 24300;
+module_param(max_page_pool_size, int, 0600);
+
 void ion_system_heap_free(struct ion_buffer *buffer)
 {
 	struct ion_heap *heap = buffer->heap;
@@ -450,6 +468,16 @@ void ion_system_heap_free(struct ion_buffer *buffer)
 	struct scatterlist *sg;
 	int i;
 	int vmid = get_secure_vmid(buffer->flags);
+	unsigned int count = 0;
+
+	for (i = 0; i < NUM_ORDERS; i++) {
+		count += ion_page_pool_total(sys_heap->cached_pools[i], true);
+		count += ion_page_pool_total(sys_heap->uncached_pools[i], true);
+	}
+
+	if (count > max_page_pool_size)
+		buffer->private_flags |= ION_PRIV_FLAG_SHRINKER_FREE;
+
 
 	if (!(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE) &&
 	    !(buffer->flags & ION_FLAG_POOL_FORCE_ALLOC)) {