On 01/10/18 at 02:16pm, Kirill A. Shutemov wrote:
> On Wed, Jan 10, 2018 at 03:08:04AM +0000, Dave Young wrote:
> > On Tue, Jan 09, 2018 at 12:05:52PM +0300, Kirill A. Shutemov wrote:
> > > On Tue, Jan 09, 2018 at 03:24:40PM +0800, Dave Young wrote:
> > > > On 01/09/18 at 01:41pm, Baoquan He wrote:
> > > > > On 01/09/18 at 09:09am, Dave Young wrote:
> > > > >
> > > > > > As for the macro name, VMCOREINFO_SYMBOL_ARRAY sounds better.
> > >
> > > Yep, that's better.
> > >
> > > > > I still think using vmcoreinfo_append_str is better. Unless we replace
> > > > > all array variables with the newly added macro.
> > > > >
> > > > > vmcoreinfo_append_str("SYMBOL(mem_section)=%lx\n",
> > > > > (unsigned long)mem_section);
> > > >
> > > > I have no strong opinion, either change all array uses or just introduce
> > > > the macro and start to use it from now on if we have similar array
> > > > symbols.
> > >
> > > Do you need some action on my side or will you folks take care about this?
> >
> > I think Baoquan was suggesting to update all array users in current
> > code, if you can check every VMCOREINFO_SYMBOL and update all the arrays
> > he will be happy. But if can not do it easily I'm fine with a
> > VMCOREINFO_SYMBOL_ARRAY changes only now, we kdump people can do it
> > later as well.
>
> It seems it's the only array we have there. swapper_pg_dir is a potential
> candidate, but it's 'unsigned long' on arm.
>
> Below it patch with corrected macro name.
>
> Please, consider applying.
>
> From 70f3a84b97f2de98d1364f7b10b7a42a1d8e9968 Mon Sep 17 00:00:00 2001
> From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> Date: Tue, 9 Jan 2018 02:55:47 +0300
> Subject: [PATCH] kdump: Write a correct address of mem_section into vmcoreinfo
>
> Depending on configuration mem_section can now be an array or a pointer
> to an array allocated dynamically. In most cases, we can continue to refer
> to it as 'mem_section' regardless of what it is.
>
> But there's one exception: '&mem_section' means "address of the array" if
> mem_section is an array, but if mem_section is a pointer, it would mean
> "address of the pointer".
>
> We've stepped onto this in kdump code. VMCOREINFO_SYMBOL(mem_section)
> writes down address of pointer into vmcoreinfo, not array as we wanted.
>
> Let's introduce VMCOREINFO_SYMBOL_ARRAY() that would handle the
> situation correctly for both cases.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Fixes: 83e3c48729d9 ("mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y")
Ack it, thanks.
Acked-by: Baoquan He <bhe@xxxxxxxxxx>
> ---
> include/linux/crash_core.h | 2 ++
> kernel/crash_core.c | 2 +-
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 06097ef30449..b511f6d24b42 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -42,6 +42,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
> vmcoreinfo_append_str("PAGESIZE=%ld\n", value)
> #define VMCOREINFO_SYMBOL(name) \
> vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)&name)
> +#define VMCOREINFO_SYMBOL_ARRAY(name) \
> + vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)name)
> #define VMCOREINFO_SIZE(name) \
> vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \
> (unsigned long)sizeof(name))
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index b3663896278e..4f63597c824d 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -410,7 +410,7 @@ static int __init crash_save_vmcoreinfo_init(void)
> VMCOREINFO_SYMBOL(contig_page_data);
> #endif
> #ifdef CONFIG_SPARSEMEM
> - VMCOREINFO_SYMBOL(mem_section);
> + VMCOREINFO_SYMBOL_ARRAY(mem_section);
> VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
> VMCOREINFO_STRUCT_SIZE(mem_section);
> VMCOREINFO_OFFSET(mem_section, section_mem_map);
> --
> Kirill A. Shutemov
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