From: Ingo Molnar <mingo@elte.hu>
To: Pekka Paalanen <pq@iki.fi>
Cc: Vegard Nossum <vegard.nossum@gmail.com>,
linux-kernel@vger.kernel.org,
Steven Rostedt <srostedt@redhat.com>,
proski@gnu.org
Subject: Re: mmiotrace broken in linux-next (8-bit writes only)
Date: Tue, 1 Jul 2008 10:15:16 +0200 [thread overview]
Message-ID: <20080701081516.GA3473@elte.hu> (raw)
In-Reply-To: <20080630234837.118fff8c@daedalus.pq.iki.fi>
* Pekka Paalanen <pq@iki.fi> wrote:
> The moment mmiotrace is enabled, I hit a NULL deref in:
>
> IP: [<ffffffff80256e71>] __trace_special+0x17c/0x23a
> Call Trace:
> [<ffffffff802573cc>] ftrace_special+0x6f/0x9a
> [<ffffffff8023e3e4>] down+0x19/0x4a
> [<ffffffff80228adc>] acquire_console_sem+0x42/0x58
> [<ffffffff8035d273>] con_flush_chars+0x28/0x43
> [<ffffffff80354a70>] write_chan+0x22e/0x334
> [<ffffffff802244e9>] ? default_wake_function+0x0/0xf
> [<ffffffff8035236d>] tty_write+0x195/0x228
> [<ffffffff80354842>] ? write_chan+0x0/0x334
> [<ffffffff8027c23a>] vfs_write+0xae/0x137
> [<ffffffff8027c6e3>] sys_write+0x47/0x70
> [<ffffffff8020b1db>] system_call_after_swapgs+0x7b/0x80
>
> which means 'entry' in __trace_special() is NULL.
>
> - ftrace_special(sem->count, 0, __LINE__);
> spin_lock_irqsave(&sem->lock, flags);
applied to tip/tracing/ftrace - thanks Pekka. This was a leftover line
from semaphore debugging.
Ingo
prev parent reply other threads:[~2008-07-01 8:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080628214626.5f9199d7@daedalus.pq.iki.fi>
[not found] ` <20080630123736.GA4011@elte.hu>
2008-06-30 20:48 ` mmiotrace broken in linux-next (8-bit writes only) Pekka Paalanen
2008-06-30 21:41 ` Vegard Nossum
2008-07-22 19:00 ` [PATCH] x86: fix mmiotrace 8-bit register decoding Pekka Paalanen
2008-07-26 15:55 ` Ingo Molnar
2008-07-01 8:15 ` Ingo Molnar [this message]
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