While trying to debug a memory leak problem, I encountered the following
problem:
After plugging/unplugging an USB CDC-ACM device, kmemleak reports multiple
copies of the following leak. It is not necessary to open the port for the
leak to happen.
unreferenced object 0xddbfd500 (size 128):
comm "kworker/0:3", pid 675, jiffies 69734 (age 916.580s)
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 1c d5 bf dd ................
backtrace:
[<da0194da>] acm_probe+0x868/0xc3c
[<cc72c809>] usb_probe_interface+0x11c/0x274
[<bbce212c>] driver_probe_device+0x22c/0x320
[<544a5b43>] bus_for_each_drv+0x58/0xb8
[<fe5944dc>] __device_attach+0xd0/0x138
[<d807c1e5>] bus_probe_device+0x84/0x8c
[<16645f2c>] device_add+0x3cc/0x5c0
[<80c11c88>] usb_set_configuration+0x448/0x7b0
[<76bdbcdf>] generic_probe+0x2c/0x78
[<bbce212c>] driver_probe_device+0x22c/0x320
[<544a5b43>] bus_for_each_drv+0x58/0xb8
[<fe5944dc>] __device_attach+0xd0/0x138
[<d807c1e5>] bus_probe_device+0x84/0x8c
[<16645f2c>] device_add+0x3cc/0x5c0
[<02a49898>] usb_new_device+0x264/0x424
[<865a481b>] hub_event+0xa20/0x1154
For each additional plug/unplug cycle, around 30 such new leaks are created.
Tested on a SAMA5D2 Xplained demo board, with a v4.18.8 kernel.
The CDC-ACM device was another SAMA5D2 device, with a composite profile
including a CDC-ACM port implemented with configfs.
--
Romain Izard
