linux-kernel - Re: [PATCH] sparc: clarify __GFP

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Message-Id: <20150302.164545.1603268042858889224.davem@davemloft.net>
Date:	Mon, 02 Mar 2015 16:45:45 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	mhocko@...e.cz
Cc:	linux-mm@...ck.org, akpm@...ux-foundation.org, hannes@...xchg.org,
	rientjes@...gle.com, david@...morbit.com, tytso@....edu,
	mgorman@...e.de, penguin-kernel@...ove.SAKURA.ne.jp,
	sparclinux@...r.kernel.org, vipul@...lsio.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sparc: clarify __GFP_NOFAIL allocation

From: Michal Hocko <mhocko@...e.cz>
Date: Mon, 2 Mar 2015 22:36:10 +0100

> 920c3ed74134 ([SPARC64]: Add basic infrastructure for MD add/remove
> notification.) has added __GFP_NOFAIL for the allocation request but
> it hasn't mentioned why is this strict requirement really needed.
> The code was handling an allocation failure and propagated it properly
> up the callchain so it is not clear why it is needed.
> 
> Dave has clarified the intention when I tried to remove the flag as not
> being necessary:
> "
> It is a serious failure.
> 
> If we miss an MDESC update due to this allocation failure, the update
> is not an event which gets retransmitted so we will lose the updated
> machine description forever.
> 
> We really need this allocation to succeed.
> "
> 
> So add a comment to clarify the nofail flag and get rid of the failure
> check because __GFP_NOFAIL allocation doesn't fail.
> 
> Signed-off-by: Michal Hocko <mhocko@...e.cz>

Acked-by: David S. Miller <davem@...emloft.net>
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