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From:   Kent Overstreet <kent.overstreet@linux.dev>
To:     Brian Foster <bfoster@redhat.com>
Cc:     linux-bcachefs@vger.kernel.org
Subject: Re: [BUG] trace_printk() broken?
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On Mon, Dec 12, 2022 at 02:20:39PM -0500, Brian Foster wrote:
> Hi,
> 
> While poking around the bcachefs tree I ran into a problem where
> trace_printk() seems to be broken. I suspect this has something to do
> with the printbuf bits as it works once I back out some of those
> changes.
> 
> What I observe is that a smaller printk with a fixed string seems to
> work as expected, but once I add some variable args the message string
> seems to get chewed up. This results in wonky formatting when reading
> /sys/kernel/debug/tracing/trace and a read of the corresponding
> trace_pipe file seems to spin in a livelock.

I recently noticed it was broken too, but different symptoms - I wasn't getting
any output at all. Thanks for the reminder, I'll have a look soon.