Re: [2.6.9-rc3-bk1] Sleeping function called from invalid context

[Andrew Morton]

sebek64@xxxxxxx (Marcel Sebek) wrote:
>
> I upgraded from 2.6.8-rc2-bk10.
>  When I run pppd, a lot of debug messages are typed out.
>  pppd uses /dev/ttyUSB0 as serial device (driver ftdi_sio).
> 
>  My .config is at http://wremcont.mysteria.cz/config-2.6.9-rc3-bk1
>  Kernel debug output is at http://wremcont.mysteria.cz/messages-2.6.9-rc3-bk1

OK, we have a problem.

Debug: sleeping function called from invalid context at mm/slab.c:2052
in_atomic():1, irqs_disabled():1
[__might_sleep+180/224] __might_sleep+0xb4/0xe0
[pg0+273102006/1069224960] hcd_submit_urb+0x106/0x190 [usbcore]
[kmem_cache_alloc+91/96] kmem_cache_alloc+0x5b/0x60
[pg0+273105606/1069224960] usb_control_msg+0x36/0xa0 [usbcore]
[pg0+272960692/1069224960] ftdi_set_termios+0x144/0x5f0 [ftdi_sio]
[pg0+273029492/1069224960] serial_set_termios+0x44/0xa0 [usbserial]
[tty_wait_until_sent+215/240] tty_wait_until_sent+0xd7/0xf0
[change_termios+480/528] change_termios+0x1e0/0x210
[set_termios+227/288] set_termios+0xe3/0x120
[tty_ioctl+1025/1248] tty_ioctl+0x401/0x4e0
[sys_ioctl+233/608] sys_ioctl+0xe9/0x260
[sysenter_past_esp+82/113] sysenter_past_esp+0x52/0x71
bad: scheduling while atomic!

In rc3 change_termios() was altered so that it calls
(*tty->driver->set_termios)() under spin_lock_irqsave(tty_termios_lock).

But ftdi_set_termios() wants to perform USB I/O, which involves sleeping
allocations all over the place.

There may be other ->set_termios() implementations which want to sleep, too.
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