2014-02-25 01:08:19

by Minchan Kim

Subject: [PATCH 1/2] zram: avoid null access when fail to alloc meta

zram_meta_alloc could be failed so caller should check it.
Otherwise, your system will be hang.

Cc: <[email protected]>
Signed-off-by: Minchan Kim <[email protected]>
---
drivers/block/zram/zram_drv.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 5ec61be793d2..21aee3edcb25 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -554,6 +554,8 @@ static ssize_t disksize_store(struct device *dev,

disksize = PAGE_ALIGN(disksize);
meta = zram_meta_alloc(disksize);
+ if (!meta)
+ return -ENOMEM;
down_write(&zram->init_lock);
if (init_done(zram)) {
up_write(&zram->init_lock);
--
1.8.5.3

2014-02-25 01:08:30

by Minchan Kim

Subject: [PATCH 2/2] zram: delete zram_init_device() function

From: Sergey Senozhatsky <[email protected]>

allocate new `zram_meta' in disksize_store() only for uninitialised
zram device, saving a number of allocations and deallocations in case
if disksize_store() was called on currently used device. at the same
time zram_meta stack variable is not necessary, because we can set
->meta directly. there is also no need in setting QUEUE_FLAG_NONROT
queue on every disksize_store(), set it once during device creation.

[[email protected]]: handled zram->meta alloc fail case.
Signed-off-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Minchan Kim <[email protected]>
---
drivers/block/zram/zram_drv.c | 25 +++++++++----------------
1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 21aee3edcb25..9baac5b76bfe 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -533,40 +533,32 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
up_write(&zram->init_lock);
}

-static void zram_init_device(struct zram *zram, struct zram_meta *meta)
-{
- /* zram devices sort of resembles non-rotational disks */
- queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
- zram->meta = meta;
- pr_debug("Initialization done!\n");
-}
-
static ssize_t disksize_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
u64 disksize;
- struct zram_meta *meta;
struct zram *zram = dev_to_zram(dev);

disksize = memparse(buf, NULL);
if (!disksize)
return -EINVAL;

- disksize = PAGE_ALIGN(disksize);
- meta = zram_meta_alloc(disksize);
- if (!meta)
- return -ENOMEM;
down_write(&zram->init_lock);
if (init_done(zram)) {
up_write(&zram->init_lock);
- zram_meta_free(meta);
pr_info("Cannot change disksize for initialized device\n");
return -EBUSY;
}

+ disksize = PAGE_ALIGN(disksize);
+ zram->meta = zram_meta_alloc(disksize);
+ if (!zram->meta) {
+ up_write(&zram->init_lock);
+ return -ENOMEM;
+ }
+
zram->disksize = disksize;
set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
- zram_init_device(zram, meta);
up_write(&zram->init_lock);

return len;
@@ -776,7 +768,8 @@ static int create_device(struct zram *zram, int device_id)

/* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
set_capacity(zram->disk, 0);
-
+ /* zram devices sort of resembles non-rotational disks */
+ queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
/*
* To ensure that we always get PAGE_SIZE aligned
* and n*PAGE_SIZED sized I/O requests.
--
1.8.5.3

2014-02-25 09:37:55

by Jerome Marchand

Subject: Re: [PATCH 1/2] zram: avoid null access when fail to alloc meta

On 02/25/2014 02:08 AM, Minchan Kim wrote:
> zram_meta_alloc could be failed so caller should check it.
> Otherwise, your system will be hang.
>
> Cc: <[email protected]>
> Signed-off-by: Minchan Kim <[email protected]>

Acked-by: Jerome Marchand <[email protected]>

> ---
> drivers/block/zram/zram_drv.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 5ec61be793d2..21aee3edcb25 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -554,6 +554,8 @@ static ssize_t disksize_store(struct device *dev,
>
> disksize = PAGE_ALIGN(disksize);
> meta = zram_meta_alloc(disksize);
> + if (!meta)
> + return -ENOMEM;
> down_write(&zram->init_lock);
> if (init_done(zram)) {
> up_write(&zram->init_lock);
>

2014-02-25 10:51:22

by Jerome Marchand

Subject: Re: [PATCH 2/2] zram: delete zram_init_device() function

On 02/25/2014 02:08 AM, Minchan Kim wrote:
> From: Sergey Senozhatsky <[email protected]>
>
> allocate new `zram_meta' in disksize_store() only for uninitialised
> zram device, saving a number of allocations and deallocations in case
> if disksize_store() was called on currently used device. at the same
> time zram_meta stack variable is not necessary, because we can set
> ->meta directly. there is also no need in setting QUEUE_FLAG_NONROT
> queue on every disksize_store(), set it once during device creation.
>
> [[email protected]]: handled zram->meta alloc fail case.
> Signed-off-by: Sergey Senozhatsky <[email protected]>
> Signed-off-by: Minchan Kim <[email protected]>

Acked-by: Jerome Marchand <[email protected]>

> ---
> drivers/block/zram/zram_drv.c | 25 +++++++++----------------
> 1 file changed, 9 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 21aee3edcb25..9baac5b76bfe 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -533,40 +533,32 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
> up_write(&zram->init_lock);
> }
>
> -static void zram_init_device(struct zram *zram, struct zram_meta *meta)
> -{
> - /* zram devices sort of resembles non-rotational disks */
> - queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
> - zram->meta = meta;
> - pr_debug("Initialization done!\n");
> -}
> -
> static ssize_t disksize_store(struct device *dev,
> struct device_attribute *attr, const char *buf, size_t len)
> {
> u64 disksize;
> - struct zram_meta *meta;
> struct zram *zram = dev_to_zram(dev);
>
> disksize = memparse(buf, NULL);
> if (!disksize)
> return -EINVAL;
>
> - disksize = PAGE_ALIGN(disksize);
> - meta = zram_meta_alloc(disksize);
> - if (!meta)
> - return -ENOMEM;
> down_write(&zram->init_lock);
> if (init_done(zram)) {
> up_write(&zram->init_lock);
> - zram_meta_free(meta);
> pr_info("Cannot change disksize for initialized device\n");
> return -EBUSY;
> }
>
> + disksize = PAGE_ALIGN(disksize);
> + zram->meta = zram_meta_alloc(disksize);
> + if (!zram->meta) {
> + up_write(&zram->init_lock);
> + return -ENOMEM;
> + }
> +
> zram->disksize = disksize;
> set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
> - zram_init_device(zram, meta);
> up_write(&zram->init_lock);
>
> return len;
> @@ -776,7 +768,8 @@ static int create_device(struct zram *zram, int device_id)
>
> /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
> set_capacity(zram->disk, 0);
> -
> + /* zram devices sort of resembles non-rotational disks */
> + queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
> /*
> * To ensure that we always get PAGE_SIZE aligned
> * and n*PAGE_SIZED sized I/O requests.
>