On Fri, May 24, 2024 at 01:46:56AM +0000, Wei Yang wrote:
> On Tue, May 21, 2024 at 10:21:52AM +0300, Mike Rapoport wrote:
> >Hi,
> >
> >On Fri, May 10, 2024 at 02:04:22AM +0000, Wei Yang wrote:
> >> When CONFIG_ARCH_KEEP_MEMBLOCK not set, we expect to discard related
> >> code and data. But it doesn't until CONFIG_MEMORY_HOTPLUG not set
> >> neither.
> >>
> >> This patch puts memblock's .text/.data into its own section, so that it
> >> only depends on CONFIG_ARCH_KEEP_MEMBLOCK to discard related code and
> >> data.
> >>
> >> After this, from the log message in mem_init_print_info(), init size
> >> increase from 2420K to 2432K on arch x86.
> >>
> >> Signed-off-by: Wei Yang <richard.weiy...@gmail.com>
> >>
> >> ---
> >> v2: fix orphan section for powerpc
> >> ---
> >> arch/powerpc/kernel/vmlinux.lds.S | 1 +
> >> include/asm-generic/vmlinux.lds.h | 14 +++++++++++++-
> >> include/linux/memblock.h | 8 ++++----
> >> 3 files changed, 18 insertions(+), 5 deletions(-)
> >>
> >> +#define __init_memblock __section(".mbinit.text") __cold notrace \
> >> + __latent_entropy
> >> +#define __initdata_memblock __section(".mbinit.data")
> >> +
> >
> >The new .mbinit.* sections should be added to scripts/mod/modpost.c
> >alongside .meminit.* sections and then I expect modpost to report a bunch
> >of section mismatches because many memblock functions are called on memory
> >hotplug even on architectures that don't select ARCH_KEEP_MEMBLOCK.
> >
>
> I tried to add some code in modpost.c, "make all" looks good.
>
> May I ask how can I trigger the "mismatch" warning?
>
> BTW, if ARCH_KEEP_MEMBLOCK unset, we would discard memblock meta-data. If
> hotplug would call memblock function, it would be dangerous?
>
> The additional code I used is like below.
>
> ---
> scripts/mod/modpost.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 937294ff164f..c837e2882904 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -777,14 +777,14 @@ static void check_section(const char *modname, struct
> elf_info *elf,
>
> #define ALL_INIT_DATA_SECTIONS \
> ".init.setup", ".init.rodata", ".meminit.rodata", \
> - ".init.data", ".meminit.data"
> + ".init.data", ".meminit.data", "mbinit.data"
should be ".mbinit.data"
>
> #define ALL_PCI_INIT_SECTIONS \
> ".pci_fixup_early", ".pci_fixup_header", ".pci_fixup_final", \
> ".pci_fixup_enable", ".pci_fixup_resume", \
> ".pci_fixup_resume_early", ".pci_fixup_suspend"
>
> -#define ALL_XXXINIT_SECTIONS ".meminit.*"
> +#define ALL_XXXINIT_SECTIONS ".meminit.*", "mbinit.*"
and ".mbinit.*"
But regardless of typos, when ARCH_KEEP_MEMBLOCK=n the .mbinit is equivalent
to .init and it should not be referenced from .meminit, so I don't think
adding it here is correct.
If I simply alias __init_memblock to __init then with
CONFIG_MEMORY_HOTPLUG=y I get
WARNING: modpost: vmlinux: section mismatch in reference: early_pfn_to_nid+0x42
(section: .meminit.text) -> memblock_search_pfn_nid (section: .init.text)
WARNING: modpost: vmlinux: section mismatch in reference:
memmap_init_range+0x142 (section: .meminit.text) -> mirrored_kernelcore
(section: .init.data)
WARNING: modpost: vmlinux: section mismatch in reference:
memmap_init_range+0x1e1 (section: .meminit.text) -> memblock (section:
.init.data)
WARNING: modpost: vmlinux: section mismatch in reference:
memmap_init_range+0x1e8 (section: .meminit.text) -> memblock (section:
.init.data)
WARNING: modpost: vmlinux: section mismatch in reference:
sparse_buffer_alloc+0x3b (section: .meminit.text) -> memblock_free (section:
.init.text)
> #define ALL_INIT_SECTIONS INIT_SECTIONS, ALL_XXXINIT_SECTIONS
> #define ALL_EXIT_SECTIONS ".exit.*"
> @@ -799,7 +799,7 @@ static void check_section(const char *modname, struct
> elf_info *elf,
>
> #define INIT_SECTIONS ".init.*"
>
> -#define ALL_TEXT_SECTIONS ".init.text", ".meminit.text", ".exit.text", \
> +#define ALL_TEXT_SECTIONS ".init.text", ".meminit.text", ".mbinit.text",
> ".exit.text", \
> TEXT_SECTIONS, OTHER_TEXT_SECTIONS
>
> enum mismatch {
>
> --
> Wei Yang
> Help you, Help me
>
--
Sincerely yours,
Mike.
