linux-kernel - Re: [PATCH 0/2] printk vs rq->lock and xtime lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20080324115738.85c72bb5.akpm@linux-foundation.org>
Date:	Mon, 24 Mar 2008 11:57:38 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	torvalds@...ux-foundation.org, mingo@...e.hu, tglx@...utronix.de,
	marcin.slusarz@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] printk vs rq->lock and xtime lock

On Mon, 24 Mar 2008 19:15:47 +0100
Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:

> How about I use the lockdep infrastructure to check if printk() is
> invoked whole holding either xtime or rq lock, and then avoid calling
> wake_up_klogd(). That way, we at least get sane debug output when the
> lock debugging infrastructure is enabled?

The core problem seems to be that printk shouldn't be calling wake_up(). 
Can we fix that?

I expect it would be acceptable to do it from the timer interrupt instead. 
For NOHZ kernels a poll when we enter the idle loop would also be needed. 

But does that cover everything?  Is it possible for a CPU to run 100% busy
while not receiving timer interrupts?  I guess so.  To receive no
interrupts at all?  Also possible.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/