From: Yi Wang <wang.yi59@zte.com.cn>
To: minchan@kernel.org
Cc: ngupta@vflare.org, sergey.senozhatsky.work@gmail.com,
axboe@kernel.dk, linux-kernel@vger.kernel.org,
linux-block@vger.kernel.org, xue.zhihong@zte.com.cn,
wang.yi59@zte.com.cn, jiang.xuexin@zte.com.cn,
zhanglin <zhang.lin16@zte.com.cn>
Subject: [PATCH v2] zram: add restriction on dynamic zram device creation
Date: Fri, 4 Sep 2020 16:52:10 +0800 [thread overview]
Message-ID: <1599209530-41015-1-git-send-email-wang.yi59@zte.com.cn> (raw)
From: zhanglin <zhang.lin16@zte.com.cn>
Add max_num_devices to limit dynamic zram device creation to prevent
potential OOM
Signed-off-by: zhanglin <zhang.lin16@zte.com.cn>
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
---
v1->v2:
change hard-coded initial max_num_devices into configurable way.
drivers/block/zram/Kconfig | 7 +++++++
drivers/block/zram/zram_drv.c | 28 +++++++++++++++++++++-------
2 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index fe7a4b7d30cf..54a369932417 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -37,3 +37,10 @@ config ZRAM_MEMORY_TRACKING
/sys/kernel/debug/zram/zramX/block_state.
See Documentation/admin-guide/blockdev/zram.rst for more information.
+
+config ZRAM_DEV_MAX_COUNT
+ int "Number of zram devices to be created"
+ depends on ZRAM
+ default 256
+ help
+ This option specifies the maximum number of zram devices.
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 36d49159140f..d1022f3c04c4 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 = CONFIG_ZRAM_DEV_MAX_COUNT;
/*
* 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 +2121,17 @@ static int __init zram_init(void)
return -EBUSY;
}
- while (num_devices != 0) {
+ if (num_devices > max_num_devices) {
+ pr_err("Number of pre-created zram devices over limit\n");
+ goto out_error;
+ }
+
+ 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 +2149,8 @@ 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 <ngupta@vflare.org>");
--
2.17.1
next reply other threads:[~2020-09-04 8:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 8:52 Yi Wang [this message]
2020-09-12 0:02 ` [PATCH v2] zram: add restriction on dynamic zram device creation Minchan Kim
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