From: Wen Gong <firstname.lastname@example.org>
To: Steven Rostedt <email@example.com>
Cc: Brian Norris <firstname.lastname@example.org>,
Subject: Re: [PATCH] ath10k: change len of trace_ath10k_log_dbg_dump for large buffer size
Date: Wed, 10 Feb 2021 10:01:57 +0800 [thread overview]
Message-ID: <email@example.com> (raw)
On 2021-02-10 05:34, Steven Rostedt wrote:
> On Tue, 9 Feb 2021 14:55:31 -0500
> Steven Rostedt <firstname.lastname@example.org> wrote:
>> > [for-next][PATCH 2/2] tracing: Use temp buffer when filtering events
>> > https://email@example.com/
>> Note, that is only used when filtering happens, which doesn't appear
>> to be
>> the case here.
> I was basing this off of the original commands, but the stack dump says
> otherwise. But it should still work.
>> > It seems like we should still try to get that fixed somehow, even if
>> > the below change is fine on its own (it probably doesn't make sense to
>> > such a large amount of data via tracepoints). It would be unfortunate
>> > for next poor soul to hit the same issues, just because they wanted to
>> > dump a few KB.
>> Yeah, it was a design decision to cap the max size of events to just
>> PAGE_SIZE. The ring buffer is broken up into pages (for zero copy
>> transfers to file systems and the network). Thus, no event is allowed
>> to be
>> bigger than a page (and actually a bit smaller)
>> That said, it shouldn't have crashed, it should have just failed to
>> I'll test it out and see why it crashed.
> Looking at the original report, I see:
> CPU: 1 PID: 141 Comm: kworker/u16:1 Not tainted 4.19.139 #162
> Does this still crash on the latest kernel?
> -- Steve
Not tested with latest kernel.
The reason is below which I said in
the per cpu buffer seems it is initilized in
it is only 1 page size as below:
page = alloc_pages_node(cpu_to_node(cpu),
GFP_KERNEL | __GFP_NORETRY, 0);
If the size of buffer to trace is more than 1 page, such as 46680, then
it trigger kernel crash/panic in my case while run trace-cmd.
After debugging, the trace_file->flags in
trace_event_buffer_lock_reserve is 0x40b while run trace-cmd, and it is
0x403 while collecting ftrace log.
ath10k mailing list
next prev parent reply other threads:[~2021-02-10 2:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-09 2:59 [PATCH] ath10k: change len of trace_ath10k_log_dbg_dump for large buffer size Wen Gong
2021-02-09 7:34 ` Kalle Valo
2021-02-09 19:35 ` Brian Norris
2021-02-09 19:55 ` Steven Rostedt
2021-02-09 21:34 ` Steven Rostedt
2021-02-10 2:01 ` Wen Gong [this message]
2021-02-10 16:30 ` Steven Rostedt
2021-02-10 16:48 ` Steven Rostedt
2021-02-10 16:53 ` Steven Rostedt
2021-03-08 7:22 ` Wen Gong
2021-02-10 2:11 ` Wen Gong
2021-02-10 2:14 ` Brian Norris
2021-02-10 2:24 ` Wen Gong
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