ACK: [Artful SRU PATCH] kdump: write correct address of mem_section into vmcoreinfo

[Kleber Souza]

On 03/05/18 10:08, Thadeu Lima de Souza Cascardo wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov at linux.intel.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1750021
> 
> 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.
> 
> Link: http://lkml.kernel.org/r/20180112162532.35896-1-kirill.shutemov@linux.intel.com
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>
> Fixes: 83e3c48729d9 ("mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y")
> Acked-by: Baoquan He <bhe at redhat.com>
> Acked-by: Dave Young <dyoung at redhat.com>
> Cc: Ingo Molnar <mingo at redhat.com>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: "H. Peter Anvin" <hpa at zytor.com>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Cc: Dave Young <dyoung at redhat.com>
> Cc: Baoquan He <bhe at redhat.com>
> Cc: Vivek Goyal <vgoyal at redhat.com>
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
> (cherry picked from commit a0b1280368d1e91ab72f849ef095b4f07a39bbf1)
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>
> ---
>  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 2df2118fbe13..b1c889225e9a 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -41,6 +41,8 @@ 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 6db80fc0810b..2d90996dbe77 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -409,7 +409,7 @@ 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);
> 

Clean cherry pick, tested to fix a regression.

Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>