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Date: Sun, 22 Feb 2009 19:33:08 +0600
Message-ID: <b9df5fa10902220533rb625291k135b3218151e12e5@mail.gmail.com>
Subject: Re: [PATCH -mm] tracing: Fix section mismatch in trace_hw_branches.c
From: Rakib Mullick <rakib.mullick@gmail.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>, markus.t.metzger@gmail.com
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On 2/21/09, Frederic Weisbecker <fweisbec@gmail.com> wrote:

> Hi,
>
>  When I saw this patch, I searched the real purpose of __cpuinit and its
>  real impact.
>  But I didn't find any comments about it inside the kernel.
>
>  But today, by looking at the discussion around latest git pull for x86
>  to mainline, I discover that __cpuinit becomes __init on UP.
>
>  So, unless I missed something, this patch seems to me very dangerous.
>  The init and reset callbacks of a tracer can be called at any time, not only
>  on initcalls time (__init functions are freed from memory after the middle stage
>  of the boot).
>  With this patch, on UP we will dereference freed memory while activating this tracer.
If the init and reset callbacks of a tracer can be called regardless
of cpu hotpluging then it is. If the tracer's init or reset doesn't
rely on cpuhotplug then it shouldn't use it.
There's a another way to fix the warning is by remove __cpuinitdata
from bts_hotcpu_notifier.

Thanks,