From: Jan Kara <jack@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Petr Mladek <pmladek@suse.cz>,
Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Dave Anderson <anderson@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Kay Sievers <kay@vrfy.org>, Jiri Kosina <jkosina@suse.cz>,
Michal Hocko <mhocko@suse.cz>, Jan Kara <jack@suse.cz>,
linux-kernel@vger.kernel.org,
Wang Long <long.wanglong@huawei.com>,
peifeiyue@huawei.com, dzickus@redhat.com, morgan.wang@huawei.com,
sasha.levin@oracle.com
Subject: Re: [PATCH 00/10] printk: Avoid deadlock in NMI + vprintk_emit() cleanup
Date: Mon, 1 Jun 2015 15:06:16 +0200 [thread overview]
Message-ID: <20150601130616.GE20288@quack.suse.cz> (raw)
In-Reply-To: <20150529135045.09d87c7ab98bf26dec95c8b3@linux-foundation.org>
On Fri 29-05-15 13:50:45, Andrew Morton wrote:
> On Mon, 25 May 2015 14:46:23 +0200 Petr Mladek <pmladek@suse.cz> wrote:
>
> > The main source of deadlocks caused by printk() in NMI context has been
> > solved by the commit a9edc88093287 ("x86/nmi: Perform a safe NMI stack
> > trace on all CPUs").
> >
> > But there are still few warnings printed in the NMI code that could
> > case a deadlock. For example, see the freeze discussed at
> > https://lkml.org/lkml/2015/5/20/481
>
> I'm not (yet) convinced that we want the entire patchset btw. Do we
> really want to try to semi-support printk from NMI? With a rather
> nasty set of hacks?
>
> Why not just delete the offending printks?
And what about WARN_ONs and BUG_ONs? Delete as well? Or just don't print
anything when we are in NMI? I agree that NMI is so problematic context
that restricting printk there makes some sence. OTOH propagating
information from NMI to user is useful as well so I'm somewhat undecided.
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2015-06-01 13:06 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-25 12:46 [PATCH 00/10] printk: Avoid deadlock in NMI + vprintk_emit() cleanup Petr Mladek
2015-05-25 12:46 ` [PATCH 01/10] printk: Avoid deadlock in NMI context Petr Mladek
2015-05-27 23:13 ` Andrew Morton
2015-05-28 12:00 ` Petr Mladek
2015-05-25 12:46 ` [PATCH 02/10] printk: Try harder to get logbuf_lock on NMI Petr Mladek
2015-05-27 23:14 ` Andrew Morton
2015-05-28 7:54 ` Jiri Kosina
2015-05-28 13:50 ` Petr Mladek
2015-05-28 20:09 ` Andrew Morton
2015-05-29 10:56 ` Petr Mladek
2015-05-29 20:46 ` Andrew Morton
2015-05-25 12:46 ` [PATCH 03/10] printk: Move the deferred printk stuff Petr Mladek
2015-05-25 12:46 ` [PATCH 04/10] printk: Merge and flush NMI buffer predictably via IRQ work Petr Mladek
2015-05-27 23:14 ` Andrew Morton
2015-05-28 13:12 ` Petr Mladek
2015-05-25 12:46 ` [PATCH 05/10] printk: Try hard to print Oops message in NMI context Petr Mladek
2015-05-25 12:46 ` [PATCH 06/10] printk: Split delayed printing of warnings from vprintk_emit() Petr Mladek
2015-05-25 12:46 ` [PATCH 07/10] printk: Split text formatting and analyze " Petr Mladek
2015-05-25 12:46 ` [PATCH 08/10] printk: Detect scheduler messages in vprintk_format_and_analyze() Petr Mladek
2015-05-25 12:46 ` [PATCH 09/10] printk: Split text storing logic from vprintk_emit() Petr Mladek
2015-05-25 12:46 ` [PATCH 10/10] printk: Split console call " Petr Mladek
2015-05-29 20:50 ` [PATCH 00/10] printk: Avoid deadlock in NMI + vprintk_emit() cleanup Andrew Morton
2015-06-01 13:06 ` Jan Kara [this message]
2015-06-02 9:46 ` long.wanglong
2015-06-02 9:52 ` Jiri Kosina
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