linux-kernel - RE: 3.7 RC1

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]

Message-ID: <426367E2313C2449837CD2DE46E7EAF930A45A90@SN2PRD0310MB382.namprd03.prod.outlook.com>
Date:	Tue, 23 Oct 2012 14:24:58 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"olaf@...fle.de" <olaf@...fle.de>,
	"apw@...onical.com" <apw@...onical.com>,
	"jasowang@...hat.com" <jasowang@...hat.com>
Subject: RE: 3.7 RC1



> -----Original Message-----
> From: Dan Carpenter [mailto:dan.carpenter@...cle.com]
> Sent: Tuesday, October 23, 2012 1:47 AM
> To: KY Srinivasan
> Cc: gregkh@...uxfoundation.org; linux-kernel@...r.kernel.org;
> devel@...uxdriverproject.org; olaf@...fle.de; apw@...onical.com;
> jasowang@...hat.com
> Subject: Re: 3.7 RC1
> 
> On Mon, Oct 22, 2012 at 04:37:45PM -0700, K. Y. Srinivasan wrote:
> >
> > While testing 3.7 RC1 I discovered that invoking the function
> orderly_poweroff()
> > from an interrupt context will trigger an ASSERT(). This was not the case till
> > recently. The comment preceding the orderly_poweroff() function claims that
> this
> > function can be invoked from any context and in the current Hyper-V util driver,
> > we support host-driven orderly shut down of the guest by invoking this
> > orderly_poweroff() function in the context of the message callback. This code
> has
> > been working for a very long time and it is broken now. Is my assumption that
> > orderly_poweroff() could be invoked from the interrupt context a wrong
> assumption?
> 
> You can't call orderly_poweroff() from interrupt context.

Thanks Dan; I am curious  to understand the basis for your assertion.
As I noted earlier  the documentation for this function clearly says it can
be called from any context. Furthermore, __orderly_poweroff(), the helper
function allocates memory with the GFP_ATOMIC flag set. Lastly, the behavior
of orderly_poweroff() has been such that this function could be called from interrupt context
for a very long time and something has changed now. For what it is worth, there are other users in
the kernel (in 3.7 RC1) that are invoking the orderly_poweroff() function from interrupt
context other than the Hyper-V shutdown handler:  fsl_hv_shutdown_isr() in drivers/virt/fsl_hypervisor.c.
I suspect there are other users as well that have made this similar assumption.


Regards,

K. Y




--
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/