linux-kernel - Re: linux-next: Tree for December 11

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Message-ID: <f19298770812161421r77a10575ia956e59a52d7efb2@mail.gmail.com>
Date:	Wed, 17 Dec 2008 01:21:29 +0300
From:	"Alexey Zaytsev" <alexey.zaytsev@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Stephen Rothwell" <sfr@...b.auug.org.au>,
	linux-next@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	"Nick Piggin" <nickpiggin@...oo.com.au>
Subject: Re: linux-next: Tree for December 11

On Wed, Dec 17, 2008 at 00:08, Ingo Molnar <mingo@...e.hu> wrote:

>>
>> The warning can also be reproduced in qemu, so it was easy to bisect.
>>
>> commit 7317d7b87edb41a9135e30be1ec3f7ef817c53dd
>> Author: Nick Piggin <nickpiggin@...oo.com.au>
>> Date:   Tue Sep 30 20:50:27 2008 +1000
>>
>>     sched: improve preempt debugging
>>
>>     This patch helped me out with a problem I recently had....
>>
>>     Basically, when the kernel lock is held, then preempt_count
>> underflow does not
>>     get detected until it is released which may be a long time (and arbitrarily,
>>     eg at different points it may be rescheduled). If the bkl is released at
>>     schedule, the resulting output is actually fairly cryptic...
>>
>>     With any other lock that elevates preempt_count, it is illegal to schedule
>>     under it (which would get found pretty quickly). bkl allows scheduling with
>>     preempt_count elevated, which makes underflows hard to debug.
>>
>>     Signed-off-by: Ingo Molnar <mingo@...e.hu>
>>
>> I understand that not this particular commit is buggy, but at least
>> I've got someone to add to the CC. ;)
>>
>> Also the author's e-mail looks suspicious.
>
> Suspicious in what way?

Does not appear in signed-off-by.

>
>        Ingo
>
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