linux-kernel - Re: [PATCH V2 1/1] lib/atomic64 using raw_spin_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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Thu, 1 Sep 2011 12:11:03 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Shan Hai <haishan.bai@...il.com>
cc:	akpm@...ux-foundation.org, eric.dumazet@...il.com,
	vapier@...too.org, asharma@...com, linux-kernel@...r.kernel.org,
	linux-rt-users@...r.kernel.org
Subject: Re: [PATCH V2 1/1] lib/atomic64 using raw_spin_lock_irq[save|resotre]
 for atomicity

On Thu, 1 Sep 2011, Thomas Gleixner wrote:

> On Thu, 1 Sep 2011, Shan Hai wrote:
> 
> > The spin_lock_irq[save|restore] could break the atomicity of the
> > atomic64_* operations in the PREEMPT-RT configuration, because
> > the spin_lock_irq[save|restore] themselves are preemptable in the
> > PREEMPT-RT, using raw variant of the spin lock could provide the
> > atomicity that atomic64_* need.
> 
> Good catch. Queued for the next release.

Though the changelog is misleading. The reason is not that they are
preemtible. 

The reason for your OOPs is that the sleeping locks are not IRQ
safe. And your system simply deadlocked due to that.

Thanks,

	tglx
--
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/