linux-kernel - Re: [tip:irq/irqdomain] irqdomain: Introduce helper function irq_domain_add

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Message-ID: <20141129145616.GC5075@pd.tnic>
Date:	Sat, 29 Nov 2014 15:56:16 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
Cc:	linux-tip-commits@...r.kernel.org, matthias.bgg@...il.com,
	tony.luck@...el.com, tglx@...utronix.de, benh@...nel.crashing.org,
	linux-kernel@...r.kernel.org, hpa@...or.com,
	grant.likely@...aro.org, wangyijing@...wei.com,
	marc.zyngier@....com, bhelgaas@...gle.com,
	yingjoe.chen@...iatek.com, mingo@...nel.org
Subject: Re: [tip:irq/irqdomain] irqdomain: Introduce helper function
 irq_domain_add_hierarchy()

On Sat, Nov 29, 2014 at 10:29:33PM +0800, Jiang Liu wrote:
>  Thanks for reporting and fixing this. How about using GFP_ATOMIC
> here?

Well, I don't see the need to use GFP_ATOMIC if we absolutely don't have
to. And in this case lockdep is, AFAICT, correct in saying that we still
can do allocations with interrupts disabled, only not go down into fs
and do all kinds of lock grabbing operations like page reclaim, writeout
or whatever it is being done nowadays there.

Yeah, this is also some old "no-no" in my memory which says that we
should almost never use GFP_ATOMIC if it can be helped.

OTOH, I wonder if this code would rather need to hand down explicit gfp
flags in case it should be able to do GFP_ATOMIC operations at some
point...

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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