From: Steven Rostedt <rostedt@goodmis.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Subject: Re: [PATCH] kernel/watchdog: flush all printk nmi buffers when hardlockup detected
Date: Tue, 11 Feb 2020 22:27:54 -0500 [thread overview]
Message-ID: <20200211222754.0185b9b3@rorschach.local.home> (raw)
In-Reply-To: <20200212030403.GC13208@google.com>
On Wed, 12 Feb 2020 12:04:03 +0900
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> wrote:
> Oh, yes, ftrace printks a lot. But I sort of forgot why don't we do
> the same for "regular" NMIs. So NMIs use per-cpu buffers, expect for
> NMIs which involve ftrace dump. I'm missing something here.
Well, ftrace_dump() is called from NMI context when the system is about
to crash (ftrace_dump_on_oops). And at that moment, we care more about
the trace than other output (it's most like to contain the information
that caused the bug).
But for things like sysrq-l, that does a printk in NMI context for
normal operations, we don't want strange races to occur and affect
other printk operations. Having them in buffers controls the output a
bit better.
But with the new printk ring buffer work, perhaps that's no longer
necessary.
-- Steve
next prev parent reply other threads:[~2020-02-12 3:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 9:48 [PATCH] kernel/watchdog: flush all printk nmi buffers when hardlockup detected Konstantin Khlebnikov
2020-02-10 22:51 ` Andrew Morton
2020-02-11 11:01 ` Konstantin Khlebnikov
2020-02-11 8:14 ` Kirill Tkhai
2020-02-11 12:36 ` Konstantin Khlebnikov
2020-02-12 14:54 ` Petr Mladek
2020-02-13 13:05 ` Konstantin Khlebnikov
2020-02-12 1:15 ` Sergey Senozhatsky
2020-02-12 2:49 ` Steven Rostedt
2020-02-12 3:04 ` Sergey Senozhatsky
2020-02-12 3:27 ` Steven Rostedt [this message]
2020-02-12 14:18 ` Petr Mladek
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