linux-kernel - Re: [PATCH 2/2] SLUB: Use GFP_PANIC for early-boot allocations

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Message-ID: <20090508161553.GL6132@lenovo>
Date:	Fri, 8 May 2009 20:15:53 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Pekka Enberg <penberg@...helsinki.fi>,
	Christoph Lameter <cl@...ux-foundation.org>,
	akpm@...ux-foundation.org, kosaki.motohiro@...fujitsu.com,
	mel@....ul.ie, riel@...hat.com, linux-kernel@...r.kernel.org,
	mingo@...e.hu, rientjes@...gle.com
Subject: Re: [PATCH 2/2] SLUB: Use GFP_PANIC for early-boot allocations

[Peter Zijlstra - Fri, May 08, 2009 at 05:50:58PM +0200]
| On Fri, 2009-05-08 at 18:45 +0300, Pekka Enberg wrote:
| 
| > On Fri, 2009-05-08 at 17:42 +0200, Peter Zijlstra wrote:
| > > BUG_ON((gfp & __GFP_PANIC) && (system_state != STATE_BOOTING));
| > 
| > There's no technical reason not to use GFP_PANIC when system_state !=
| > STATE_BOOTING so I don't think it's needed. It's just that GFP_PANIC
| > (and BUG_ON) is IMHO too harsh for create_unique_id().
| 
| Shouldn't we handle every allocation failure after booting?

Definitely

| 
| I think it _is_ a bug to panic on allocation failures once we're
| running.
|

But Peter I believe there was no suggestion to use GFP_PANIC everywhere
to get rid of error handling. But rather to use it in case if kmalloc is
followed by BUG_ON.

| 
| I'm really not very fond of __GFP_PANIC as it stands, it seems to
| suggest its OK to ignore allocation failures, which would bring us back
| to the original UNIX error handling :/
| 
	-- Cyrill
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