From: Steven Rostedt <rostedt@goodmis.org>
To: Chuck Lever III <chuck.lever@oracle.com>
Cc: John 'Warthog9' Hawley <warthog9@eaglescrag.net>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: possible trace_printk() bug in v5.19-rc1
Date: Mon, 27 Jun 2022 15:01:15 -0400 [thread overview]
Message-ID: <20220627150115.066e17d1@gandalf.local.home> (raw)
In-Reply-To: <25C37F40-7D8E-41C6-961F-0774C8138CCB@oracle.com>
On Mon, 27 Jun 2022 17:19:18 +0000
Chuck Lever III <chuck.lever@oracle.com> wrote:
> > Would you be able to send me a trace.dat file that has this issue?
>
> Sending under separate cover.
I found this is the kallsyms output:
ffffffffac820000 b __brk_early_pgt_alloc
ffffffffac830000 B _end
ffffffffac830000 B __brk_limit
ffffffffc0948205 0944410 t qrtr_alloc_ctrl_packet [qrtr]
ffffffffc0944470 t qrtr_node_enqueue [qrtr]
ffffffffc094d100 b __key.5 [qrtr]
ffffffffc09448b0 t qrtr_reset_ports [qrtr]
ffffffffc094c1c0 d qrtr_ports [qrtr]
ffffffffc094d100 b __key.3 [qrtr]
ffffffffc094d100 b __key.4 [qrtr]
The line with:
ffffffffc0948205 0944410 t qrtr_alloc_ctrl_packet [qrtr]
Causes the parsing to stop, because it is not of a proper format. It has
that extra "0944410" in it, which will break the parsing.
Now the question is, why does that exist? And yes, that's a kernel bug.
The kallsyms code that outputs this file is:
static int s_show(struct seq_file *m, void *p)
{
void *value;
struct kallsym_iter *iter = m->private;
/* Some debugging symbols have no name. Ignore them. */
if (!iter->name[0])
return 0;
value = iter->show_value ? (void *)iter->value : NULL;
if (iter->module_name[0]) {
char type;
/*
* Label it "global" if it is exported,
* "local" if not exported.
*/
type = iter->exported ? toupper(iter->type) :
tolower(iter->type);
seq_printf(m, "%px %c %s\t[%s]\n", value,
type, iter->name, iter->module_name);
} else
seq_printf(m, "%px %c %s\n", value,
iter->type, iter->name);
return 0;
}
So how did it get that strange output.
Hmm, I bet it is because trace-cmd reads it in BUFSIZ blocks, and that the
seq_file code got confused when parsing between two elements, I bet
something got dropped. I'll go see if there was any seq_file updates that
could have caused this.
-- Steve
next prev parent reply other threads:[~2022-06-27 19:01 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-16 15:22 possible trace_printk() bug in v5.19-rc1 Chuck Lever III
2022-06-16 15:34 ` Steven Rostedt
2022-06-16 15:36 ` Chuck Lever III
2022-06-16 15:43 ` Steven Rostedt
2022-06-16 18:07 ` Chuck Lever III
2022-06-17 19:50 ` Steven Rostedt
2022-06-18 1:28 ` Chuck Lever III
2022-06-20 0:57 ` Chuck Lever III
2022-06-24 18:23 ` Chuck Lever III
2022-06-24 23:08 ` Steven Rostedt
2022-06-25 17:15 ` Chuck Lever III
2022-06-25 17:45 ` Steven Rostedt
2022-06-25 18:28 ` John 'Warthog9' Hawley
2022-06-26 3:01 ` John 'Warthog9' Hawley
2022-06-27 17:08 ` Chuck Lever III
2022-06-27 17:11 ` Steven Rostedt
2022-06-27 17:19 ` Chuck Lever III
2022-06-27 19:01 ` Steven Rostedt [this message]
2022-06-28 15:24 ` Steven Rostedt
2022-06-25 18:50 ` Chuck Lever III
2022-06-25 23:01 ` Steven Rostedt
2022-06-26 17:09 ` Chuck Lever III
2022-06-27 15:43 ` Steven Rostedt
2022-06-27 15:51 ` Chuck Lever III
2022-06-27 16:02 ` Steven Rostedt
2022-06-28 3:59 ` Steven Rostedt
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