Date: Sun, 6 May 2007 14:08:57 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: Valdis.Kletnieks@vt.edu, linux-kernel@vger.kernel.org
Subject: Re: 2.6.21-mm1
Message-Id: <20070506140857.550edb37.akpm@linux-foundation.org>
In-Reply-To: <20070506205732.GC10396@uranus.ravnborg.org>
References: <20070505014955.8f3990b5.akpm@linux-foundation.org>
	<17296.1178434189@turing-police.cc.vt.edu>
	<20070506205732.GC10396@uranus.ravnborg.org>
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On Sun, 6 May 2007 22:57:32 +0200 Sam Ravnborg <sam@ravnborg.org> wrote:

> On Sun, May 06, 2007 at 02:49:49AM -0400, Valdis.Kletnieks@vt.edu wrote:
> > On Sat, 05 May 2007 01:49:55 PDT, Andrew Morton said:
> > > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.21/2.6.21-mm1/
> > 
> >   MODPOST vmlinux
> > WARNING: mm/built-in.o - Section mismatch: reference to .init.text: from .text between 'kmem_cache_create' (at offset 0x20dff) and 'cache_reap'
> > WARNING: mm/built-in.o - Section mismatch: reference to .init.text: from .text between 'kmem_cache_create' (at offset 0x20e41) and 'cache_reap'
> > 
> > Built with CONFIG_SLAB, CONFIG_SMP, x86_64.
> 
> It comes from this code (mm/slab.c):
> /*
>  * For setting up all the kmem_list3s for cache whose buffer_size is same as
>  * size of kmem_list3.
>  */
> static void __init set_up_list3s(struct kmem_cache *cachep, int index)
> {
> 	int node;
> 
> 	for_each_online_node(node) {
> 		cachep->nodelists[node] = &initkmem_list3[index + node];
> 		cachep->nodelists[node]->next_reap = jiffies +
> 		    REAPTIMEOUT_LIST3 +
> 		    ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
> 	}
> }
> 
> It is supposed to be used only during early init and thus marked __init.
> And initkmem_list3 is marked __initdata so that matches.
> 
> But set_up_list3s() is used outside __init marked functions and thus result in an error.
> 
> I do not know how to fix this.
> 

Yes, this is one of those rare places which triggers a warning but where no
changes are needed.

I'm thinking that we could address this with a new section __nowarn and
__nowarndata (or whatever).  These will have the same behaviour as regular
.text and .data, only the symbol-checking tool would know about them and
would suppress the warnings.

Perhaps there's some other way of communication this information from the C
level down into the checker - I haven't thought about it much.
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