2009-01-19 21:47:09

by Gary Hade

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Subject: [PATCH] x86_64: remove kernel_physical_mapping_init() from init section


kernel_physical_mapping_init() is called during memory hotplug
so it does not belong in the init section.

If the kernel is built with CONFIG_DEBUG_SECTION_MISMATCH=y on
the make command line, arch/x86/mm/init_64.c is compiled with
the -fno-inline-functions-called-once gcc option defeating
inlining of kernel_physical_mapping_init() within init_memory_mapping().
When kernel_physical_mapping_init() is not inlined it is placed
in the .init.text section according to the __init in it's current
declaration. A later call to kernel_physical_mapping_init() during
a memory hotplug operation encounters an int3 trap because the
.init.text section memory has been freed. This patch eliminates
the crash caused by the int3 trap by moving the non-inlined
kernel_physical_mapping_init() from .init.text to .meminit.text.

Signed-off-by: Gary Hade <[email protected]>

---

--- linux-2.6.29-rc2/arch/x86/mm/init_64.c.orig 2009-01-16 14:38:34.000000000 -0800
+++ linux-2.6.29-rc2/arch/x86/mm/init_64.c 2009-01-16 14:39:21.000000000 -0800
@@ -596,7 +596,7 @@ static void __init init_gbpages(void)
direct_gbpages = 0;
}

-static unsigned long __init kernel_physical_mapping_init(unsigned long start,
+static unsigned long __meminit kernel_physical_mapping_init(unsigned long start,
unsigned long end,
unsigned long page_size_mask)
{


2009-01-19 23:32:58

by Ingo Molnar

[permalink] [raw]
Subject: Re: [PATCH] x86_64: remove kernel_physical_mapping_init() from init section


* Gary Hade <[email protected]> wrote:

> kernel_physical_mapping_init() is called during memory hotplug so it
> does not belong in the init section.
>
> If the kernel is built with CONFIG_DEBUG_SECTION_MISMATCH=y on the make
> command line, arch/x86/mm/init_64.c is compiled with the
> -fno-inline-functions-called-once gcc option defeating inlining of
> kernel_physical_mapping_init() within init_memory_mapping(). When
> kernel_physical_mapping_init() is not inlined it is placed in the
> .init.text section according to the __init in it's current declaration.
> A later call to kernel_physical_mapping_init() during a memory hotplug
> operation encounters an int3 trap because the .init.text section memory
> has been freed. This patch eliminates the crash caused by the int3 trap
> by moving the non-inlined kernel_physical_mapping_init() from .init.text
> to .meminit.text.
>
> Signed-off-by: Gary Hade <[email protected]>

applied to tip/x86/urgent, thanks Gary!

Ingo