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From: Daniel Wagner <wagi@monom.org>
To: Borislav Petkov <bp@alien8.de>, Steven Rostedt <rostedt@goodmis.org>
Cc: Corey Minyard <minyard@acm.org>,
	linux-rt-users@vger.kernel.org,
	Corey Minyard <cminyard@mvista.com>,
	Tony Luck <tony.luck@intel.com>
Subject: Re: [PATCH][RT] x86: Fix an RT MCE crash
Date: Fri, 1 Jul 2016 11:20:46 +0200	[thread overview]
Message-ID: <f96ce3fa-adca-773f-562c-dac2e75d65a9@monom.org> (raw)
In-Reply-To: <20160630160128.GA4365@pd.tnic>

On 06/30/2016 06:01 PM, Borislav Petkov wrote:
>>>>>   #ifdef CONFIG_PREEMPT_RT_FULL
>>>>> +static bool notify_work_ready __read_mostly;
>>>>>   struct task_struct *mce_notify_helper;
>>>>>   
>>>>>   static int mce_notify_helper_thread(void *unused)
>>>>> @@ -1386,12 +1387,14 @@ static int mce_notify_work_init(void)
> 
> Hmm, what is mce_notify_work_init() ?
> 
> This must be some RT-homegrown thing.
> 
> What it is supposed to do? Upstream is much different from 3.10 or
> whatever that kernel version is.

The notify work snippet defers the execution of mce_notify_irq to a
kthread using swork (simple work, which is based on simple wait [1]).

mce_notify_irq() can't be run in IRQ context because of
wake_up_interruptible() which calls mutex_lock() eventually with
CONFIG_PREEMPT_RT_FULL.

cheers,
daniel

[1]
https://git.kernel.org/cgit/linux/kernel/git/rt/linux-rt-devel.git/tree/include/linux/swork.h?h=linux-4.6.y-rt

https://git.kernel.org/cgit/linux/kernel/git/rt/linux-rt-devel.git/tree/kernel/sched/swork.c?h=linux-4.6.y-rt

  parent reply	other threads:[~2016-07-01  9:26 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-30 13:24 [PATCH][RT] x86: Fix an RT MCE crash minyard
2016-06-30 13:43 ` Steven Rostedt
2016-06-30 14:49   ` Corey Minyard
2016-06-30 15:51     ` Steven Rostedt
2016-06-30 15:58       ` Corey Minyard
2016-06-30 16:01       ` Borislav Petkov
2016-06-30 16:17         ` Luck, Tony
2016-06-30 16:40           ` Corey Minyard
2016-06-30 17:01             ` Borislav Petkov
2016-06-30 17:18               ` Corey Minyard
2016-06-30 17:26                 ` Borislav Petkov
2016-06-30 17:54                   ` Corey Minyard
2016-06-30 18:22                     ` Borislav Petkov
2016-06-30 19:44                       ` Corey Minyard
2016-06-30 20:34                         ` Borislav Petkov
2016-06-30 22:47                           ` Corey Minyard
2016-07-01  7:20                             ` Borislav Petkov
2016-07-06  0:59                               ` Corey Minyard
2016-07-06  8:37                                 ` Borislav Petkov
2016-07-06 12:03                                   ` Corey Minyard
2016-07-06 13:32                                     ` Steven Rostedt
2016-07-06 13:43                                       ` Sebastian Andrzej Siewior
2016-07-11 17:32                                         ` Steven Rostedt
2016-07-01  9:20         ` Daniel Wagner [this message]
2016-06-30 16:04       ` Corey Minyard

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