On 05/16/2013 02:45 AM, Alexander Holler wrote:
Hello,
after some pain because the "big step" (ecbbfd4) happened while the support for
my AMD CPU was broken and thus git bisect hit a series of kernels which didn't boot, I've
finally found the cause for a memory corruption: tty_ldisc_release().
What happens is the following:
tty_port is self-destructing, that means it destroys itself in
tty_port.c:tty_port_destructor() when the last reference is gone. E.g. in case of
rfcomm this happens with the call to tty->ops->close() in
tty_io.c:tty_release().
The problem here is that tty_io.c:tty_release() calls
tty_ldisc.c:tty_ldisc_release() which uses the tty_port to flush the ldisc work
queues.
In the best case this hits a BUG() in cancel_work_sync() but often it just
causes a memory corruption without a BUG() got hit before.
Hi Alexander,
Actually, the problem is that tty->ops->close() shouldn't be
the last kref on the port.
It doesn't look to me like device removal is being handled
properly.
Regards,
Peter Hurley
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