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

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Date:	Fri, 29 Jul 2016 10:52:09 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Vegard Nossum <vegard.nossum@...cle.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org,
	Vegard Nossum <vegard.nossum@...cle.com>,
	"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"

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...

Cheers,
Rusty.


>
>     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
>
>     CPU: 3 PID: 32211 Comm: trinity-c3 Not tainted 4.7.0-rc7+ #19
>                                        ^^^^^^^^^^^
>     Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
>      0000000000000000 ffff8800b8a17160 ffffffff81971441 ffff88011a3c4c80
>      ffff88011a3c4c80 ffff8800b8a17198 ffffffff81158067 0000000000000de6
>      ffff88011a3c4c80 ffffffff8390e07c 0000000000000184 0000000000000000
>     Call Trace:
>     [...]
>
>     BUG: sleeping function called from invalid context at arch/x86/mm/fault.c:1309
>     in_atomic(): 0, irqs_disabled(): 0, pid: 32211, name: trinity-c3
>     Preemption disabled at:[<ffffffff8119db33>] down_trylock+0x13/0x80
>
>     CPU: 3 PID: 32211 Comm: trinity-c3 Not tainted 4.7.0-rc7+ #19
>                                        ^^^^^^^^^^^
>     Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
>      0000000000000000 ffff8800b8a17e08 ffffffff81971441 ffff88011a3c4c80
>      ffff88011a3c4c80 ffff8800b8a17e40 ffffffff81158067 0000000000000000
>      ffff88011a3c4c80 ffffffff83437b20 000000000000051d 0000000000000000
>     Call Trace:
>     [...]
>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Rusty Russel <rusty@...tcorp.com.au>
> Signed-off-by: Vegard Nossum <vegard.nossum@...cle.com>
> ---
>  kernel/sched/core.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 97ee9ac..7171cf9 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -7573,6 +7573,7 @@ void ___might_sleep(const char *file, int line, int preempt_offset)
>  	}
>  #endif
>  	dump_stack();
> +	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
>  }
>  EXPORT_SYMBOL(___might_sleep);
>  #endif
> -- 
> 1.9.1