linux-kernel - Re: [PATCH] mm: Warn about costly page allocation

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Date:	Mon, 9 Jul 2012 23:12:26 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Cong Wang <xiyou.wangcong@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] mm: Warn about costly page allocation

Hi Cong,

On Mon, Jul 09, 2012 at 12:53:22PM +0000, Cong Wang wrote:
> On Mon, 09 Jul 2012 at 08:46 GMT, Minchan Kim <minchan@...nel.org> wrote:
> >> 
> >> WARN_ON_ONCE would tell you what is trying to satisfy the allocation.
> >
> > Do you mean that it would be better to use WARN_ON_ONCE rather than raw printk?
> > If so, I would like to insist raw printk because WARN_ON_ONCE could be disabled
> > by !CONFIG_BUG.
> > If I miss something, could you elaborate it more?
> >
> 
> Raw printk could be disabled by !CONFIG_PRINTK too, and given that:

Yes.
In such case, It is very hard to diagnose the system so at least
we enables CONFIG_PRINTK.

> 
> config PRINTK
>         default y
>         bool "Enable support for printk" if EXPERT
> 		    
> config BUG
>         bool "BUG() support" if EXPERT
>         default y
> 
> they are both configurable only when ERPERT, so we don't need to
> worry much. :)

Embedded can use CONFIG_PRINTK and !CONFIG_BUG for size optimization
and printk(pr_xxx) + dump_stack is common technic used in all over kernel
sources. Do you have any reason you don't like it?


> 
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