2020-01-24 20:55:53

by Maxim Mikityanskiy

Subject: [PATCH] Bluetooth: btrtl: Use kvmalloc for FW allocations

Currently, kmemdup is applied to the firmware data, and it invokes
kmalloc under the hood. The firmware size and patch_length are big (more
than PAGE_SIZE), and on some low-end systems (like ASUS E202SA) kmalloc
may fail to allocate a contiguous chunk under high memory usage and
fragmentation:

Bluetooth: hci0: RTL: examining hci_ver=06 hci_rev=000a lmp_ver=06 lmp_subver=8821
Bluetooth: hci0: RTL: rom_version status=0 version=1
Bluetooth: hci0: RTL: loading rtl_bt/rtl8821a_fw.bin
kworker/u9:2: page allocation failure: order:4, mode:0x40cc0(GFP_KERNEL|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0
<stack trace follows>

As firmware load happens on each resume, Bluetooth will stop working
after several iterations, when the kernel fails to allocate an order-4
page.

This patch replaces kmemdup with kvmalloc+memcpy. It's not required to
have a contiguous chunk here, because it's not mapped to the device
directly.

Signed-off-by: Maxim Mikityanskiy <[email protected]>
---
drivers/bluetooth/btrtl.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/bluetooth/btrtl.c b/drivers/bluetooth/btrtl.c
index f838537f9f89..577cfa3329db 100644
--- a/drivers/bluetooth/btrtl.c
+++ b/drivers/bluetooth/btrtl.c
@@ -370,11 +370,11 @@ static int rtlbt_parse_firmware(struct hci_dev *hdev,
* the end.
*/
len = patch_length;
- buf = kmemdup(btrtl_dev->fw_data + patch_offset, patch_length,
- GFP_KERNEL);
+ buf = kvmalloc(patch_length, GFP_KERNEL);
if (!buf)
return -ENOMEM;

+ memcpy(buf, btrtl_dev->fw_data + patch_offset, patch_length - 4);
memcpy(buf + patch_length - 4, &epatch_info->fw_version, 4);

*_buf = buf;
@@ -460,8 +460,10 @@ static int rtl_load_file(struct hci_dev *hdev, const char *name, u8 **buff)
if (ret < 0)
return ret;
ret = fw->size;
- *buff = kmemdup(fw->data, ret, GFP_KERNEL);
- if (!*buff)
+ *buff = kvmalloc(fw->size, GFP_KERNEL);
+ if (*buff)
+ memcpy(*buff, fw->data, ret);
+ else
ret = -ENOMEM;

release_firmware(fw);
@@ -499,14 +501,14 @@ static int btrtl_setup_rtl8723b(struct hci_dev *hdev,
goto out;

if (btrtl_dev->cfg_len > 0) {
- tbuff = kzalloc(ret + btrtl_dev->cfg_len, GFP_KERNEL);
+ tbuff = kvzalloc(ret + btrtl_dev->cfg_len, GFP_KERNEL);
if (!tbuff) {
ret = -ENOMEM;
goto out;
}

memcpy(tbuff, fw_data, ret);
- kfree(fw_data);
+ kvfree(fw_data);

memcpy(tbuff + ret, btrtl_dev->cfg_data, btrtl_dev->cfg_len);
ret += btrtl_dev->cfg_len;
@@ -519,14 +521,14 @@ static int btrtl_setup_rtl8723b(struct hci_dev *hdev,
ret = rtl_download_firmware(hdev, fw_data, ret);

out:
- kfree(fw_data);
+ kvfree(fw_data);
return ret;
}

void btrtl_free(struct btrtl_device_info *btrtl_dev)
{
- kfree(btrtl_dev->fw_data);
- kfree(btrtl_dev->cfg_data);
+ kvfree(btrtl_dev->fw_data);
+ kvfree(btrtl_dev->cfg_data);
kfree(btrtl_dev);
}
EXPORT_SYMBOL_GPL(btrtl_free);
--
2.25.0

2020-01-24 20:59:51

by Marcel Holtmann

Subject: Re: [PATCH] Bluetooth: btrtl: Use kvmalloc for FW allocations

Hi Maxim,

> Currently, kmemdup is applied to the firmware data, and it invokes
> kmalloc under the hood. The firmware size and patch_length are big (more
> than PAGE_SIZE), and on some low-end systems (like ASUS E202SA) kmalloc
> may fail to allocate a contiguous chunk under high memory usage and
> fragmentation:
>
> Bluetooth: hci0: RTL: examining hci_ver=06 hci_rev=000a lmp_ver=06 lmp_subver=8821
> Bluetooth: hci0: RTL: rom_version status=0 version=1
> Bluetooth: hci0: RTL: loading rtl_bt/rtl8821a_fw.bin
> kworker/u9:2: page allocation failure: order:4, mode:0x40cc0(GFP_KERNEL|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0
> <stack trace follows>
>
> As firmware load happens on each resume, Bluetooth will stop working
> after several iterations, when the kernel fails to allocate an order-4
> page.
>
> This patch replaces kmemdup with kvmalloc+memcpy. It's not required to
> have a contiguous chunk here, because it's not mapped to the device
> directly.
>
> Signed-off-by: Maxim Mikityanskiy <[email protected]>
> ---
> drivers/bluetooth/btrtl.c | 20 +++++++++++---------
> 1 file changed, 11 insertions(+), 9 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel