From: Daniel Thompson <daniel.thompson@linaro.org>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Sumit Garg <sumit.garg@linaro.org>,
Petr Mladek <pmladek@suse.com>,
Jason Wessel <jason.wessel@windriver.com>,
Douglas Anderson <dianders@chromium.org>,
kgdb-bugreport@lists.sourceforge.net,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
John Ogness <john.ogness@linutronix.de>
Subject: Re: [PATCH] printk/kdb: Redirect printk messages into kdb in any context
Date: Wed, 10 Jun 2020 17:41:40 +0100 [thread overview]
Message-ID: <20200610164140.tgzcn5oip2gzgmze@holly.lan> (raw)
In-Reply-To: <20200515163638.GI42471@jagdpanzerIV.localdomain>
On Sat, May 16, 2020 at 01:36:38AM +0900, Sergey Senozhatsky wrote:
> On (20/05/15 17:32), Sumit Garg wrote:
> > > Can I please have some context what problem does this solve?
> >
> > You can find the problem description here [1] which leads to this fix.
>
> [..]
>
> > [1] https://lkml.org/lkml/2020/5/12/213
>
> Thanks for the link. I'm slightly surprised it took so many years
> to notice the addition of printk_nmi/printk_safe :)
Rather by coincidence (at least I think its a coincidence) the problem
has recently become much more obvious.
0d00449c7a28 ("x86: Replace ist_enter() with nmi_enter()") just brought
this to the surface by treating debug traps as NMIs. This means the CPU
that takes a breakpoint, and where almost all of the kdb printk() calls
take place, will now unconditionally have printk() interception enabled.
Daniel.
next prev parent reply other threads:[~2020-06-10 16:41 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 8:48 [PATCH] kgdb: Fix broken handling of printk() in NMI context Sumit Garg
2020-05-12 14:25 ` Daniel Thompson
2020-05-13 13:34 ` Sumit Garg
2020-05-14 8:42 ` Petr Mladek
2020-05-15 5:46 ` Sumit Garg
2020-05-15 8:50 ` [PATCH] printk/kdb: Redirect printk messages into kdb in any context Petr Mladek
2020-05-15 10:33 ` Sergey Senozhatsky
2020-05-15 12:02 ` Sumit Garg
2020-05-15 16:36 ` Sergey Senozhatsky
2020-05-15 16:52 ` Doug Anderson
2020-05-18 6:19 ` Sumit Garg
2020-06-10 16:41 ` Daniel Thompson [this message]
2020-06-11 7:27 ` Sergey Senozhatsky
2020-06-11 7:58 ` Petr Mladek
2020-05-15 13:48 ` Daniel Thompson
2020-05-15 16:24 ` Sergey Senozhatsky
2020-05-18 9:21 ` Petr Mladek
2020-05-20 4:21 ` Sergey Senozhatsky
2020-05-20 9:35 ` Daniel Thompson
2020-05-20 10:22 ` [PATCH v2] " Petr Mladek
2020-05-20 11:17 ` Sergey Senozhatsky
2020-05-20 16:07 ` Daniel Thompson
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