From: zhanglin <zhang.li...@zte.com.cn>
Add max_num_devices to limit dynamic zram device creation to prevent
potential OOM
Signed-off-by: zhanglin <zhang.li...@zte.com.cn>
---
drivers/block/zram/zram_drv.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 36d49159140f..4f2c4eef5051 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -43,8 +43,9 @@ static DEFINE_MUTEX(zram_index_mutex);
static int zram_major;
static const char *default_compressor = "lzo-rle";
-/* Module params (documentation at end) */
static unsigned int num_devices = 1;
+/* Module params (documentation at end) */
+static unsigned int max_num_devices = 8;
/*
* Pages that compress to sizes equals or greater than this are stored
* uncompressed in memory.
@@ -2013,10 +2014,16 @@ static ssize_t hot_add_show(struct class *class,
struct class_attribute *attr,
char *buf)
{
- int ret;
+ int ret = -ENOSPC;
mutex_lock(&zram_index_mutex);
+ if (num_devices >= max_num_devices) {
+ mutex_unlock(&zram_index_mutex);
+ return ret;
+ }
ret = zram_add();
+ if (ret >= 0)
+ num_devices += 1;
mutex_unlock(&zram_index_mutex);
if (ret < 0)
@@ -2046,8 +2053,10 @@ static ssize_t hot_remove_store(struct class *class,
zram = idr_find(&zram_index_idr, dev_id);
if (zram) {
ret = zram_remove(zram);
- if (!ret)
+ if (!ret) {
idr_remove(&zram_index_idr, dev_id);
+ num_devices -= 1;
+ }
} else {
ret = -ENODEV;
}
@@ -2089,6 +2098,7 @@ static void destroy_devices(void)
static int __init zram_init(void)
{
int ret;
+ unsigned int i;
ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare",
zcomp_cpu_up_prepare, zcomp_cpu_dead);
@@ -2111,13 +2121,15 @@ static int __init zram_init(void)
return -EBUSY;
}
- while (num_devices != 0) {
+ if (num_devices > max_num_devices)
+ num_devices = max_num_devices;
+
+ for (i = 0; i < num_devices; i++) {
mutex_lock(&zram_index_mutex);
ret = zram_add();
mutex_unlock(&zram_index_mutex);
if (ret < 0)
goto out_error;
- num_devices--;
}
return 0;
@@ -2135,8 +2147,8 @@ static void __exit zram_exit(void)
module_init(zram_init);
module_exit(zram_exit);
-module_param(num_devices, uint, 0);
-MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
+module_param(max_num_devices, uint, 0);
+MODULE_PARM_DESC(max_num_devices, "Max number of created zram devices");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Nitin Gupta <ngu...@vflare.org>");
--
2.17.1
