[Makedumpfile PATCH v2] Fix SECTION_MAP_MASK for kernel >= v.13

[Atsushi Kumagai]

>commit 2d070eab2e82 "mm: consider zone which is not fully populated to
>have holes" added a new flag SECTION_IS_ONLINE and therefore
>SECTION_MAP_MASK has been changed. We are not able to find correct
>mem_map in makedumpfile for kernel version v4.13-rc1 and onward because
>of the above kernel change.
>
>This patch fixes the MASK value keeping the code backward compatible
>
>Signed-off-by: Pratyush Anand <panand at redhat.com>
>---
>v1->v2: Improved kernel_version comparison to take care of stable kernel
>versions as well.

Thanks, I'll merge this into v1.6.3.

Regards,
Atsushi Kumagai

> makedumpfile.c | 5 ++++-
> makedumpfile.h | 4 +++-
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
>diff --git a/makedumpfile.c b/makedumpfile.c
>index 30230a15a2e7..c975651ca357 100644
>--- a/makedumpfile.c
>+++ b/makedumpfile.c
>@@ -3304,7 +3304,10 @@ section_mem_map_addr(unsigned long addr)
> 		return NOT_KV_ADDR;
> 	}
> 	map = ULONG(mem_section + OFFSET(mem_section.section_mem_map));
>-	map &= SECTION_MAP_MASK;
>+	if (info->kernel_version < KERNEL_VERSION(4, 13, 0))
>+		map &= SECTION_MAP_MASK_4_12;
>+	else
>+		map &= SECTION_MAP_MASK;
> 	free(mem_section);
>
> 	return map;
>diff --git a/makedumpfile.h b/makedumpfile.h
>index 8a05794843fb..322f28c632b0 100644
>--- a/makedumpfile.h
>+++ b/makedumpfile.h
>@@ -183,7 +183,9 @@ isAnon(unsigned long mapping)
> #define SECTIONS_PER_ROOT()	(info->sections_per_root)
> #define SECTION_ROOT_MASK()	(SECTIONS_PER_ROOT() - 1)
> #define SECTION_NR_TO_ROOT(sec)	((sec) / SECTIONS_PER_ROOT())
>-#define SECTION_MAP_LAST_BIT	(1UL<<2)
>+#define SECTION_IS_ONLINE	(1UL<<2)
>+#define SECTION_MAP_LAST_BIT	(1UL<<3)
>+#define SECTION_MAP_MASK_4_12	(~(SECTION_IS_ONLINE-1))
> #define SECTION_MAP_MASK	(~(SECTION_MAP_LAST_BIT-1))
> #define NR_SECTION_ROOTS()	divideup(num_section, SECTIONS_PER_ROOT())
> #define SECTION_NR_TO_PFN(sec)	((sec) << PFN_SECTION_SHIFT())
>--
>2.9.4
>