linux-kernel - Re: Regression with orderly

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Message-ID: <20130312201351.GF11268@two.firstfloor.org>
Date:	Tue, 12 Mar 2013 21:13:51 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Lucas De Marchi <lucas.de.marchi@...il.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@...ba.org>, david@...son.dropbear.id.au,
	Kees Cook <keescook@...omium.org>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Feng Hong <hongfeng@...vell.com>,
	Lucas De Marchi <lucas.demarchi@...fusion.mobi>
Subject: Re: Regression with orderly_poweroff()

> Btw. There is another "strange" user, arch/x86/kernel/cpu/mcheck/mce.c.
> It uses mce_trigger_work to call call_usermodehelper(UMH_NO_WAIT).
> Why? UMH_NO_WAIT is already atomic. And the !work_pending() check is
> confusing, schedule_work(schedule_work) checks it is not pending.

I think you're right, the additional step shouldn't be needed.

The MCE Handler uses the trick to do this in MCE context if the
interrupts were enabled earlier. 

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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