| Message ID | 20221108115324.270361-1-zengheng4@huawei.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | gpiolib: fix memory leak in gpiochip_setup_dev | expand |
On Tue, Nov 08, 2022 at 07:53:24PM +0800, Zeng Heng wrote: > gcdev_register & gcdev_unregister call device_add & device_del to > request/release source. But in device_add, the dev->p allocated by > device_private_init is not released by device_del. > > So when calling gcdev_unregister to release gdev, it needs put_device > to release dev in the following. > > Otherwise, kmemleak would report memory leak such as below: > > unreferenced object 0xffff88810b406400 (size 512): > comm "python3", pid 1682, jiffies 4295346908 (age 24.090s) > hex dump (first 32 bytes): > 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... > ff ff ff ff ff ff ff ff a0 5e 23 90 ff ff ff ff .........^#..... > backtrace: > [<00000000a58ee5fe>] kmalloc_trace+0x22/0x110 > [<0000000045fe2058>] device_add+0xb34/0x1130 > [<00000000d778b45f>] cdev_device_add+0x83/0xe0 > [<0000000089f948ed>] gpiolib_cdev_register+0x73/0xa0 > [<00000000a3a8a316>] gpiochip_setup_dev+0x1c/0x70 > [<00000000787227b4>] gpiochip_add_data_with_key+0x10f6/0x1bf0 > [<000000009ac5742c>] devm_gpiochip_add_data_with_key+0x2e/0x80 > [<00000000bf2b23d9>] xra1403_probe+0x192/0x1b0 [gpio_xra1403] > [<000000005b5ef2d4>] spi_probe+0xe1/0x140 > [<000000002b26f6f1>] really_probe+0x17c/0x3f0 > [<00000000dd2dad9c>] __driver_probe_device+0xe3/0x170 > [<000000005ca60d2a>] device_driver_attach+0x34/0x80 > [<00000000e9db90db>] bind_store+0x10b/0x1a0 > [<00000000e2650f8a>] drv_attr_store+0x49/0x70 > [<0000000080a80b2b>] sysfs_kf_write+0x8c/0xb0 > [<00000000a28b45b9>] kernfs_fop_write_iter+0x216/0x2e0 > > unreferenced object 0xffff888100de9800 (size 512): > comm "python3", pid 264, jiffies 4294737615 (age 33.514s) > hex dump (first 32 bytes): > 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... > ff ff ff ff ff ff ff ff a0 5e 63 a1 ff ff ff ff .........^c..... > backtrace: > [<00000000bcc571d0>] kmalloc_trace+0x22/0x110 > [<00000000eeb06124>] device_add+0xb34/0x1130 > [<000000007e5cd2fd>] cdev_device_add+0x83/0xe0 > [<000000008f6bcd3a>] gpiolib_cdev_register+0x73/0xa0 > [<0000000012c93b24>] gpiochip_setup_dev+0x1c/0x70 > [<00000000a24b646a>] gpiochip_add_data_with_key+0x10f6/0x1bf0 > [<000000000c225212>] tpic2810_probe+0x16e/0x196 [gpio_tpic2810] > [<00000000b52d04ff>] i2c_device_probe+0x651/0x680 > [<0000000058d3ff6b>] really_probe+0x17c/0x3f0 > [<00000000586f43d3>] __driver_probe_device+0xe3/0x170 > [<000000003f428602>] device_driver_attach+0x34/0x80 > [<0000000040e91a1b>] bind_store+0x10b/0x1a0 > [<00000000c1d990b9>] drv_attr_store+0x49/0x70 > [<00000000a23bfc22>] sysfs_kf_write+0x8c/0xb0 > [<00000000064e6572>] kernfs_fop_write_iter+0x216/0x2e0 > [<00000000026ce093>] vfs_write+0x658/0x810 > > Because at the point of gpiochip_setup_dev here, where dev.release > does not set yet, calling put_device would cause the warning of > no release function and double-free in the following fault handler > route (when kfree dev_name). So directly calling kfree to release > dev->p here in case of memory leak. > > Fixes: 1f5eb8b17f02 ("gpiolib: fix sysfs when cdev is not selected") I'm confused. You say "gcdev_register & gcdev_unregister call device_add & device_del" - which is only the case when CONFIG_GPIO_CDEV is not set. But your trace shows CONFIG_GPIO_CDEV is set, as otherwise gpiolib_cdev_register() would not exist. Can you clarify the configuration in which you are seeing the problem? Assuming CONFIG_GPIO_CDEV is NOT set: Provide a more appropriate trace.
On Wed, Nov 09, 2022 at 12:57:48AM +0800, Kent Gibson wrote: > On Tue, Nov 08, 2022 at 07:53:24PM +0800, Zeng Heng wrote: > > gcdev_register & gcdev_unregister call device_add & device_del to > > request/release source. But in device_add, the dev->p allocated by > > device_private_init is not released by device_del. > > > > So when calling gcdev_unregister to release gdev, it needs put_device > > to release dev in the following. > > > > Otherwise, kmemleak would report memory leak such as below: > > > > unreferenced object 0xffff88810b406400 (size 512): > > comm "python3", pid 1682, jiffies 4295346908 (age 24.090s) > > hex dump (first 32 bytes): > > 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... > > ff ff ff ff ff ff ff ff a0 5e 23 90 ff ff ff ff .........^#..... > > backtrace: > > [<00000000a58ee5fe>] kmalloc_trace+0x22/0x110 > > [<0000000045fe2058>] device_add+0xb34/0x1130 > > [<00000000d778b45f>] cdev_device_add+0x83/0xe0 > > [<0000000089f948ed>] gpiolib_cdev_register+0x73/0xa0 > > [<00000000a3a8a316>] gpiochip_setup_dev+0x1c/0x70 > > [<00000000787227b4>] gpiochip_add_data_with_key+0x10f6/0x1bf0 > > [<000000009ac5742c>] devm_gpiochip_add_data_with_key+0x2e/0x80 > > [<00000000bf2b23d9>] xra1403_probe+0x192/0x1b0 [gpio_xra1403] > > [<000000005b5ef2d4>] spi_probe+0xe1/0x140 > > [<000000002b26f6f1>] really_probe+0x17c/0x3f0 > > [<00000000dd2dad9c>] __driver_probe_device+0xe3/0x170 > > [<000000005ca60d2a>] device_driver_attach+0x34/0x80 > > [<00000000e9db90db>] bind_store+0x10b/0x1a0 > > [<00000000e2650f8a>] drv_attr_store+0x49/0x70 > > [<0000000080a80b2b>] sysfs_kf_write+0x8c/0xb0 > > [<00000000a28b45b9>] kernfs_fop_write_iter+0x216/0x2e0 > > > > unreferenced object 0xffff888100de9800 (size 512): > > comm "python3", pid 264, jiffies 4294737615 (age 33.514s) > > hex dump (first 32 bytes): > > 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... > > ff ff ff ff ff ff ff ff a0 5e 63 a1 ff ff ff ff .........^c..... > > backtrace: > > [<00000000bcc571d0>] kmalloc_trace+0x22/0x110 > > [<00000000eeb06124>] device_add+0xb34/0x1130 > > [<000000007e5cd2fd>] cdev_device_add+0x83/0xe0 > > [<000000008f6bcd3a>] gpiolib_cdev_register+0x73/0xa0 > > [<0000000012c93b24>] gpiochip_setup_dev+0x1c/0x70 > > [<00000000a24b646a>] gpiochip_add_data_with_key+0x10f6/0x1bf0 > > [<000000000c225212>] tpic2810_probe+0x16e/0x196 [gpio_tpic2810] > > [<00000000b52d04ff>] i2c_device_probe+0x651/0x680 > > [<0000000058d3ff6b>] really_probe+0x17c/0x3f0 > > [<00000000586f43d3>] __driver_probe_device+0xe3/0x170 > > [<000000003f428602>] device_driver_attach+0x34/0x80 > > [<0000000040e91a1b>] bind_store+0x10b/0x1a0 > > [<00000000c1d990b9>] drv_attr_store+0x49/0x70 > > [<00000000a23bfc22>] sysfs_kf_write+0x8c/0xb0 > > [<00000000064e6572>] kernfs_fop_write_iter+0x216/0x2e0 > > [<00000000026ce093>] vfs_write+0x658/0x810 > > > > Because at the point of gpiochip_setup_dev here, where dev.release > > does not set yet, calling put_device would cause the warning of > > no release function and double-free in the following fault handler > > route (when kfree dev_name). So directly calling kfree to release > > dev->p here in case of memory leak. > > > > Fixes: 1f5eb8b17f02 ("gpiolib: fix sysfs when cdev is not selected") > > I'm confused. You say "gcdev_register & gcdev_unregister call device_add > & device_del" - which is only the case when CONFIG_GPIO_CDEV is not set. > > But your trace shows CONFIG_GPIO_CDEV is set, as otherwise > gpiolib_cdev_register() would not exist. > > Can you clarify the configuration in which you are seeing the problem? > > Assuming CONFIG_GPIO_CDEV is NOT set: > > Provide a more appropriate trace. > > From a reading of the device_add() documentation, there is a problem if > the device_add() fails - in that case put_device() should be called - and > it is not, instead gpiochip_setup_dev() returns immediately - not going > via the err_remove_device path where your fix is??. > The correct fix for that would be to change the gcdev_register() to call > put_device() if device_add() fails. > Ignore that - as you mentioned the dev.release hasn't been set at that point. Having another look at this, I don't think the problem is related to the Fixed commit at all - it looks more general. How did you conclude that that commit introduced the problem? Is it easily repeatable and have you bisected for it? Cheers, Kent.
On 2022/11/9 13:12, Kent Gibson wrote: > On Wed, Nov 09, 2022 at 12:57:48AM +0800, Kent Gibson wrote: >> On Tue, Nov 08, 2022 at 07:53:24PM +0800, Zeng Heng wrote: >>> gcdev_register & gcdev_unregister call device_add & device_del to >>> request/release source. But in device_add, the dev->p allocated by >>> device_private_init is not released by device_del. >>> >>> So when calling gcdev_unregister to release gdev, it needs put_device >>> to release dev in the following. >>> >>> Otherwise, kmemleak would report memory leak such as below: >>> >>> unreferenced object 0xffff88810b406400 (size 512): >>> comm "python3", pid 1682, jiffies 4295346908 (age 24.090s) >>> hex dump (first 32 bytes): >>> 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... >>> ff ff ff ff ff ff ff ff a0 5e 23 90 ff ff ff ff .........^#..... >>> backtrace: >>> [<00000000a58ee5fe>] kmalloc_trace+0x22/0x110 >>> [<0000000045fe2058>] device_add+0xb34/0x1130 >>> [<00000000d778b45f>] cdev_device_add+0x83/0xe0 >>> [<0000000089f948ed>] gpiolib_cdev_register+0x73/0xa0 >>> [<00000000a3a8a316>] gpiochip_setup_dev+0x1c/0x70 >>> [<00000000787227b4>] gpiochip_add_data_with_key+0x10f6/0x1bf0 >>> [<000000009ac5742c>] devm_gpiochip_add_data_with_key+0x2e/0x80 >>> [<00000000bf2b23d9>] xra1403_probe+0x192/0x1b0 [gpio_xra1403] >>> [<000000005b5ef2d4>] spi_probe+0xe1/0x140 >>> [<000000002b26f6f1>] really_probe+0x17c/0x3f0 >>> [<00000000dd2dad9c>] __driver_probe_device+0xe3/0x170 >>> [<000000005ca60d2a>] device_driver_attach+0x34/0x80 >>> [<00000000e9db90db>] bind_store+0x10b/0x1a0 >>> [<00000000e2650f8a>] drv_attr_store+0x49/0x70 >>> [<0000000080a80b2b>] sysfs_kf_write+0x8c/0xb0 >>> [<00000000a28b45b9>] kernfs_fop_write_iter+0x216/0x2e0 >>> >>> unreferenced object 0xffff888100de9800 (size 512): >>> comm "python3", pid 264, jiffies 4294737615 (age 33.514s) >>> hex dump (first 32 bytes): >>> 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... >>> ff ff ff ff ff ff ff ff a0 5e 63 a1 ff ff ff ff .........^c..... >>> backtrace: >>> [<00000000bcc571d0>] kmalloc_trace+0x22/0x110 >>> [<00000000eeb06124>] device_add+0xb34/0x1130 >>> [<000000007e5cd2fd>] cdev_device_add+0x83/0xe0 >>> [<000000008f6bcd3a>] gpiolib_cdev_register+0x73/0xa0 >>> [<0000000012c93b24>] gpiochip_setup_dev+0x1c/0x70 >>> [<00000000a24b646a>] gpiochip_add_data_with_key+0x10f6/0x1bf0 >>> [<000000000c225212>] tpic2810_probe+0x16e/0x196 [gpio_tpic2810] >>> [<00000000b52d04ff>] i2c_device_probe+0x651/0x680 >>> [<0000000058d3ff6b>] really_probe+0x17c/0x3f0 >>> [<00000000586f43d3>] __driver_probe_device+0xe3/0x170 >>> [<000000003f428602>] device_driver_attach+0x34/0x80 >>> [<0000000040e91a1b>] bind_store+0x10b/0x1a0 >>> [<00000000c1d990b9>] drv_attr_store+0x49/0x70 >>> [<00000000a23bfc22>] sysfs_kf_write+0x8c/0xb0 >>> [<00000000064e6572>] kernfs_fop_write_iter+0x216/0x2e0 >>> [<00000000026ce093>] vfs_write+0x658/0x810 >>> >>> Because at the point of gpiochip_setup_dev here, where dev.release >>> does not set yet, calling put_device would cause the warning of >>> no release function and double-free in the following fault handler >>> route (when kfree dev_name). So directly calling kfree to release >>> dev->p here in case of memory leak. >>> >>> Fixes: 1f5eb8b17f02 ("gpiolib: fix sysfs when cdev is not selected") >> I'm confused. You say "gcdev_register & gcdev_unregister call device_add >> & device_del" - which is only the case when CONFIG_GPIO_CDEV is not set. >> >> But your trace shows CONFIG_GPIO_CDEV is set, as otherwise >> gpiolib_cdev_register() would not exist. >> >> Can you clarify the configuration in which you are seeing the problem? >> >> Assuming CONFIG_GPIO_CDEV is NOT set: >> >> Provide a more appropriate trace. >> >> From a reading of the device_add() documentation, there is a problem if >> the device_add() fails - in that case put_device() should be called - and >> it is not, instead gpiochip_setup_dev() returns immediately - not going >> via the err_remove_device path where your fix is??. >> The correct fix for that would be to change the gcdev_register() to call >> put_device() if device_add() fails. >> > Ignore that - as you mentioned the dev.release hasn't been set at that > point. > > Having another look at this, I don't think the problem is related to the > Fixed commit at all - it looks more general. > How did you conclude that that commit introduced the problem? > Is it easily repeatable and have you bisected for it? > > Cheers, > Kent. > Thanks to your patience for taking another look at this mail. And allow me to claim that I indeed do the inject-fault test and regression test based on the patch. My test environment has included CONFIG_GPIO_CDEV config, but no matter includes this config or not, there is still memory leak in fault handle route about dev->p because of calling device_add. Apologize for the fixed commit is not accurate, and exactly it's this one: Fixes: 159f3cd92f17 ("gpiolib: Defer gpio device setup until after gpiolib initialization") If everything is all right, I would send the second version patch and correct fix tag. thanks all, Zeng Heng
On Wed, Nov 09, 2022 at 04:27:26PM +0800, Zeng Heng wrote: > > On 2022/11/9 13:12, Kent Gibson wrote: > > On Wed, Nov 09, 2022 at 12:57:48AM +0800, Kent Gibson wrote: > > > On Tue, Nov 08, 2022 at 07:53:24PM +0800, Zeng Heng wrote: > > > > gcdev_register & gcdev_unregister call device_add & device_del to > > > > request/release source. But in device_add, the dev->p allocated by > > > > device_private_init is not released by device_del. > > > > > > > > So when calling gcdev_unregister to release gdev, it needs put_device > > > > to release dev in the following. > > > > > > > > Otherwise, kmemleak would report memory leak such as below: > > > > > > > > unreferenced object 0xffff88810b406400 (size 512): > > > > comm "python3", pid 1682, jiffies 4295346908 (age 24.090s) > > > > hex dump (first 32 bytes): > > > > 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... > > > > ff ff ff ff ff ff ff ff a0 5e 23 90 ff ff ff ff .........^#..... > > > > backtrace: > > > > [<00000000a58ee5fe>] kmalloc_trace+0x22/0x110 > > > > [<0000000045fe2058>] device_add+0xb34/0x1130 > > > > [<00000000d778b45f>] cdev_device_add+0x83/0xe0 > > > > [<0000000089f948ed>] gpiolib_cdev_register+0x73/0xa0 > > > > [<00000000a3a8a316>] gpiochip_setup_dev+0x1c/0x70 > > > > [<00000000787227b4>] gpiochip_add_data_with_key+0x10f6/0x1bf0 > > > > [<000000009ac5742c>] devm_gpiochip_add_data_with_key+0x2e/0x80 > > > > [<00000000bf2b23d9>] xra1403_probe+0x192/0x1b0 [gpio_xra1403] > > > > [<000000005b5ef2d4>] spi_probe+0xe1/0x140 > > > > [<000000002b26f6f1>] really_probe+0x17c/0x3f0 > > > > [<00000000dd2dad9c>] __driver_probe_device+0xe3/0x170 > > > > [<000000005ca60d2a>] device_driver_attach+0x34/0x80 > > > > [<00000000e9db90db>] bind_store+0x10b/0x1a0 > > > > [<00000000e2650f8a>] drv_attr_store+0x49/0x70 > > > > [<0000000080a80b2b>] sysfs_kf_write+0x8c/0xb0 > > > > [<00000000a28b45b9>] kernfs_fop_write_iter+0x216/0x2e0 > > > > > > > > unreferenced object 0xffff888100de9800 (size 512): > > > > comm "python3", pid 264, jiffies 4294737615 (age 33.514s) > > > > hex dump (first 32 bytes): > > > > 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... > > > > ff ff ff ff ff ff ff ff a0 5e 63 a1 ff ff ff ff .........^c..... > > > > backtrace: > > > > [<00000000bcc571d0>] kmalloc_trace+0x22/0x110 > > > > [<00000000eeb06124>] device_add+0xb34/0x1130 > > > > [<000000007e5cd2fd>] cdev_device_add+0x83/0xe0 > > > > [<000000008f6bcd3a>] gpiolib_cdev_register+0x73/0xa0 > > > > [<0000000012c93b24>] gpiochip_setup_dev+0x1c/0x70 > > > > [<00000000a24b646a>] gpiochip_add_data_with_key+0x10f6/0x1bf0 > > > > [<000000000c225212>] tpic2810_probe+0x16e/0x196 [gpio_tpic2810] > > > > [<00000000b52d04ff>] i2c_device_probe+0x651/0x680 > > > > [<0000000058d3ff6b>] really_probe+0x17c/0x3f0 > > > > [<00000000586f43d3>] __driver_probe_device+0xe3/0x170 > > > > [<000000003f428602>] device_driver_attach+0x34/0x80 > > > > [<0000000040e91a1b>] bind_store+0x10b/0x1a0 > > > > [<00000000c1d990b9>] drv_attr_store+0x49/0x70 > > > > [<00000000a23bfc22>] sysfs_kf_write+0x8c/0xb0 > > > > [<00000000064e6572>] kernfs_fop_write_iter+0x216/0x2e0 > > > > [<00000000026ce093>] vfs_write+0x658/0x810 > > > > > > > > Because at the point of gpiochip_setup_dev here, where dev.release > > > > does not set yet, calling put_device would cause the warning of > > > > no release function and double-free in the following fault handler > > > > route (when kfree dev_name). So directly calling kfree to release > > > > dev->p here in case of memory leak. > > > > > > > > Fixes: 1f5eb8b17f02 ("gpiolib: fix sysfs when cdev is not selected") > > > I'm confused. You say "gcdev_register & gcdev_unregister call device_add > > > & device_del" - which is only the case when CONFIG_GPIO_CDEV is not set. > > > > > > But your trace shows CONFIG_GPIO_CDEV is set, as otherwise > > > gpiolib_cdev_register() would not exist. > > > > > > Can you clarify the configuration in which you are seeing the problem? > > > > > > Assuming CONFIG_GPIO_CDEV is NOT set: > > > > > > Provide a more appropriate trace. > > > > > > From a reading of the device_add() documentation, there is a problem if > > > the device_add() fails - in that case put_device() should be called - and > > > it is not, instead gpiochip_setup_dev() returns immediately - not going > > > via the err_remove_device path where your fix is??. > > > The correct fix for that would be to change the gcdev_register() to call > > > put_device() if device_add() fails. > > > > > Ignore that - as you mentioned the dev.release hasn't been set at that > > point. > > > > Having another look at this, I don't think the problem is related to the > > Fixed commit at all - it looks more general. > > How did you conclude that that commit introduced the problem? > > Is it easily repeatable and have you bisected for it? > > > > Cheers, > > Kent. > > Thanks to your patience for taking another look at this mail. > No problem - my bad for initially responding without giving it more consideration. > And allow me to claim that I indeed do the inject-fault test and regression > test based on the patch. > > > My test environment has included CONFIG_GPIO_CDEV config, but no matter > includes this config or not, > > there is still memory leak in fault handle route about dev->p because of > calling device_add. > > > Apologize for the fixed commit is not accurate, and exactly it's this one: > > Fixes: 159f3cd92f17 ("gpiolib: Defer gpio device setup until after gpiolib > initialization") > > > If everything is all right, I would send the second version patch and > correct fix tag. > Yeah, that makes more sense - it has been there since that section of code was reworked - quite some time ago. Good catch. Cheers, Kent.
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 4756ea08894f..fa659af86d07 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -539,6 +539,7 @@ static int gpiochip_setup_dev(struct gpio_device *gdev) err_remove_device: gcdev_unregister(gdev); + kfree(gdev->dev.p); return ret; }
gcdev_register & gcdev_unregister call device_add & device_del to request/release source. But in device_add, the dev->p allocated by device_private_init is not released by device_del. So when calling gcdev_unregister to release gdev, it needs put_device to release dev in the following. Otherwise, kmemleak would report memory leak such as below: unreferenced object 0xffff88810b406400 (size 512): comm "python3", pid 1682, jiffies 4295346908 (age 24.090s) hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... ff ff ff ff ff ff ff ff a0 5e 23 90 ff ff ff ff .........^#..... backtrace: [<00000000a58ee5fe>] kmalloc_trace+0x22/0x110 [<0000000045fe2058>] device_add+0xb34/0x1130 [<00000000d778b45f>] cdev_device_add+0x83/0xe0 [<0000000089f948ed>] gpiolib_cdev_register+0x73/0xa0 [<00000000a3a8a316>] gpiochip_setup_dev+0x1c/0x70 [<00000000787227b4>] gpiochip_add_data_with_key+0x10f6/0x1bf0 [<000000009ac5742c>] devm_gpiochip_add_data_with_key+0x2e/0x80 [<00000000bf2b23d9>] xra1403_probe+0x192/0x1b0 [gpio_xra1403] [<000000005b5ef2d4>] spi_probe+0xe1/0x140 [<000000002b26f6f1>] really_probe+0x17c/0x3f0 [<00000000dd2dad9c>] __driver_probe_device+0xe3/0x170 [<000000005ca60d2a>] device_driver_attach+0x34/0x80 [<00000000e9db90db>] bind_store+0x10b/0x1a0 [<00000000e2650f8a>] drv_attr_store+0x49/0x70 [<0000000080a80b2b>] sysfs_kf_write+0x8c/0xb0 [<00000000a28b45b9>] kernfs_fop_write_iter+0x216/0x2e0 unreferenced object 0xffff888100de9800 (size 512): comm "python3", pid 264, jiffies 4294737615 (age 33.514s) hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... ff ff ff ff ff ff ff ff a0 5e 63 a1 ff ff ff ff .........^c..... backtrace: [<00000000bcc571d0>] kmalloc_trace+0x22/0x110 [<00000000eeb06124>] device_add+0xb34/0x1130 [<000000007e5cd2fd>] cdev_device_add+0x83/0xe0 [<000000008f6bcd3a>] gpiolib_cdev_register+0x73/0xa0 [<0000000012c93b24>] gpiochip_setup_dev+0x1c/0x70 [<00000000a24b646a>] gpiochip_add_data_with_key+0x10f6/0x1bf0 [<000000000c225212>] tpic2810_probe+0x16e/0x196 [gpio_tpic2810] [<00000000b52d04ff>] i2c_device_probe+0x651/0x680 [<0000000058d3ff6b>] really_probe+0x17c/0x3f0 [<00000000586f43d3>] __driver_probe_device+0xe3/0x170 [<000000003f428602>] device_driver_attach+0x34/0x80 [<0000000040e91a1b>] bind_store+0x10b/0x1a0 [<00000000c1d990b9>] drv_attr_store+0x49/0x70 [<00000000a23bfc22>] sysfs_kf_write+0x8c/0xb0 [<00000000064e6572>] kernfs_fop_write_iter+0x216/0x2e0 [<00000000026ce093>] vfs_write+0x658/0x810 Because at the point of gpiochip_setup_dev here, where dev.release does not set yet, calling put_device would cause the warning of no release function and double-free in the following fault handler route (when kfree dev_name). So directly calling kfree to release dev->p here in case of memory leak. Fixes: 1f5eb8b17f02 ("gpiolib: fix sysfs when cdev is not selected") Signed-off-by: Zeng Heng <zengheng4@huawei.com> --- drivers/gpio/gpiolib.c | 1 + 1 file changed, 1 insertion(+)