RE: [PATCH] ACPICA: fix a memleak issue related to ACPI/GPIO

["Kaneda, Erik" <erik.kaneda@xxxxxxxxx>]

> -----Original Message-----
> From: chenxiang <chenxiang66@xxxxxxxxxxxxx>
> Sent: Tuesday, May 11, 2021 8:30 PM
> To: Moore, Robert <robert.moore@xxxxxxxxx>; Kaneda, Erik
> <erik.kaneda@xxxxxxxxx>; Wysocki, Rafael J <rafael.j.wysocki@xxxxxxxxx>;
> hoan@xxxxxxxxxxxxxxxxxxxxxx; fancer.lancer@xxxxxxxxx
> Cc: linux-acpi@xxxxxxxxxxxxxxx; linux-gpio@xxxxxxxxxxxxxxx;
> linuxarm@xxxxxxxxxx; Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
> Subject: [PATCH] ACPICA: fix a memleak issue related to ACPI/GPIO
> 
> From: Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
> 
> There is a memleak reported as follows:
> 
> unreferenced object 0xffff00208ff85a00 (size 128):
>   comm "swapper/0", pid 1, jiffies 4294892588 (age 887.572s)
>   hex dump (first 32 bytes):
>     00 00 00 00 02 00 00 00 08 5a f8 8f 20 00 ff ff  .........Z.. ...
>     08 5a f8 8f 20 00 ff ff 00 00 00 00 00 00 00 00  .Z.. ...........
> backtrace:
>     [<00000000bc25bad8>] slab_post_alloc_hook+0x80/0x2e0
>     [<000000008d547074>] kmem_cache_alloc+0x194/0x2c0
>     [<00000000b08da9ad>] acpi_os_create_semaphore+0x3c/0x78
>     [<0000000024816c0a>] acpi_ev_install_space_handler+0x214/0x274
>     [<00000000d93a5ac2>] acpi_install_address_space_handler+0x64/0xb0
>     [<0000000098c37a45>] acpi_gpiochip_add+0x130/0x348
>     [<00000000c1cf4b42>] gpiochip_add_data_with_key+0x79c/0xdd0
>     [<000000005ce539e9>] devm_gpiochip_add_data_with_key+0x30/0x90
>     [<00000000a3038b8d>] dwapb_gpio_probe+0x3e4/0x7e8
>     [<0000000047a03eba>] platform_probe+0x68/0xe0
>     [<00000000dc15c501>] really_probe+0x17c/0x4a0
>     [<00000000aa1f123d>] driver_probe_device+0x68/0xd0
>     [<00000000d97646e0>] device_driver_attach+0x74/0x80
>     [<0000000073d5b3e5>] __driver_attach+0x8c/0xe0
>     [<00000000ff60d118>] bus_for_each_dev+0x7c/0xd8
>     [<00000000b018393d>] driver_attach+0x24/0x30
> 
> It requires to delete the handler object in function
> acpi_remove_address_space_handler() but it just up the sem with function
> acpi_os_release_mutex(), so use acpi_os_delete_mutex() instead of
> acpi_os_release_mutex() in function
> acpi_remove_address_space_handler().
> 
> Signed-off-by: Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
> ---
>  drivers/acpi/acpica/evxfregn.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/acpica/evxfregn.c b/drivers/acpi/acpica/evxfregn.c
> index b1ff0a8..4db0bec 100644
> --- a/drivers/acpi/acpica/evxfregn.c
> +++ b/drivers/acpi/acpica/evxfregn.c
> @@ -201,7 +201,7 @@ acpi_remove_address_space_handler(acpi_handle
> device,
> 
>  			/* Now we can delete the handler object */
> 

Hi Xiang,
 
> -			acpi_os_release_mutex(handler_obj-
> >address_space.
> +			acpi_os_delete_mutex(handler_obj->address_space.
>  					      context_mutex);

Thanks for this suggestion! Instead of acpi_os_delete_mutex, could you try using acpi_ut_remove_reference instead?
I believe this will is a safer option. Please test this and see if it fixes the memory leak.

Thanks,
Erik

>  			acpi_ut_remove_reference(handler_obj);
>  			goto unlock_and_exit;
> --
> 2.8.1