linux-kernel - Re: [PATCH] sched/core: add taint on "BUG: sleeping function called from invalid context"

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Message-ID: <579AF7C2.9020009@oracle.com>
Date:	Fri, 29 Jul 2016 08:29:22 +0200
From:	Vegard Nossum <vegard.nossum@...cle.com>
To:	Rusty Russell <rusty@...tcorp.com.au>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH] sched/core: add taint on "BUG: sleeping function called
 from invalid context"

On 07/29/2016 03:22 AM, Rusty Russell wrote:
> Vegard Nossum <vegard.nossum@...cle.com> writes:
>> Seeing this, it occurs to me that we should probably add a taint here:
>
> Taint has traditionally meant "the user did something unsupported, take
> the bug report with a grain of salt".  Such as force removing a module.
>
> So this seems wrong...

There are many types of taints. This is the one you mentioned:

    2 - A module was force loaded by insmod -f.

This is the one I'd like to set:

  512 - A kernel warning has occurred.

(from Documentation/sysctl/kernel.txt).

The flag I want to set is also set on any kind of WARN().

>>      BUG: sleeping function called from invalid context at mm/slab.h:388
>>      in_atomic(): 0, irqs_disabled(): 0, pid: 32211, name: trinity-c3
>>      Preemption disabled at:[<ffffffff811aaa37>] console_unlock+0x2f7/0x930

I am not proposing this patch on a whim: it was actually hiding real
bugs because I only saw an oops that happened later when in fact the
real bug happened where the "sleeping function called from invalid
context" was called.


Vegard