Atsushi Kumagai <ats-kumagai at wm.jp.nec.com> writes:
> Hello Vitaly,
>
>>_count member was renamed to _refcount in linux commit commit 0139aa7b7fa12
>>("mm: rename _count, field of the struct page, to _refcount") and this
>>broke makedumpfile. The reason for making the change was to find all users
>>accessing it directly and not through the recommended API. I tried
>>suggesting to revert the change but failed, I see no other choice than to
>>start supporting both _count and _refcount in makedumpfile.
>>
>>Signed-off-by: Vitaly Kuznetsov <vkuznets at redhat.com>
>
> Thanks for your report and fixing it.
>
>>---
>>- 'crash' tool is now broken as well.
>>---
>> makedumpfile.c | 18 +++++++++++++++++-
>> makedumpfile.h | 1 +
>> 2 files changed, 18 insertions(+), 1 deletion(-)
>>
>>diff --git a/makedumpfile.c b/makedumpfile.c
>>index 853b999..96dfe39 100644
>>--- a/makedumpfile.c
>>+++ b/makedumpfile.c
>>@@ -1580,6 +1580,13 @@ get_structure_info(void)
>> SIZE_INIT(page, "page");
>> OFFSET_INIT(page.flags, "page", "flags");
>> OFFSET_INIT(page._count, "page", "_count");
>>+ if (OFFSET(page._count) == NOT_FOUND_STRUCTURE) {
>>+ info->flag_refcount = TRUE;
>>+ OFFSET_INIT(page._count, "page", "_refcount");
>>+ } else {
>>+ info->flag_refcount = FALSE;
>>+ }
>>+
>
> I prefer to check the new symbol name first since it's likely
> from now on.
>
In that case I suggest we also rename '_count' filed to '_refcount' and
'flag_refcount' to 'flag_count' to support this default. I'll send v2.
>> OFFSET_INIT(page.mapping, "page", "mapping");
>> OFFSET_INIT(page._mapcount, "page", "_mapcount");
>> OFFSET_INIT(page.private, "page", "private");
>>@@ -2151,7 +2158,10 @@ write_vmcoreinfo_data(void)
>> * write the member offset of 1st kernel
>> */
>> WRITE_MEMBER_OFFSET("page.flags", page.flags);
>>- WRITE_MEMBER_OFFSET("page._count", page._count);
>>+ if (info->flag_refcount)
>>+ WRITE_MEMBER_OFFSET("page._refcount", page._count);
>>+ else
>>+ WRITE_MEMBER_OFFSET("page._count", page._count);
>> WRITE_MEMBER_OFFSET("page.mapping", page.mapping);
>> WRITE_MEMBER_OFFSET("page.lru", page.lru);
>> WRITE_MEMBER_OFFSET("page._mapcount", page._mapcount);
>>@@ -2492,6 +2502,12 @@ read_vmcoreinfo(void)
>>
>> READ_MEMBER_OFFSET("page.flags", page.flags);
>> READ_MEMBER_OFFSET("page._count", page._count);
>>+ if (OFFSET(page._count) == NOT_FOUND_STRUCTURE) {
>>+ info->flag_refcount = TRUE;
>>+ READ_MEMBER_OFFSET("page._refcount", page._count);
>>+ } else {
>>+ info->flag_refcount = FALSE;
>>+ }
>
> same as OFFSET_INIT.
>
> Thanks,
> Atsushi Kumagai
>
>> READ_MEMBER_OFFSET("page.mapping", page.mapping);
>> READ_MEMBER_OFFSET("page.lru", page.lru);
>> READ_MEMBER_OFFSET("page._mapcount", page._mapcount);
>>diff --git a/makedumpfile.h b/makedumpfile.h
>>index 251d4bf..3742389 100644
>>--- a/makedumpfile.h
>>+++ b/makedumpfile.h
>>@@ -1100,6 +1100,7 @@ struct DumpInfo {
>> int flag_nospace; /* the flag of "No space on device" error */
>> int flag_vmemmap; /* kernel supports vmemmap address space */
>> int flag_excludevm; /* -e - excluding unused vmemmap pages */
>>+ int flag_refcount; /* _count is renamed to _refcount */
>> unsigned long vaddr_for_vtop; /* virtual address for debugging */
>> long page_size; /* size of page */
>> long page_shift;
>>--
>>2.5.5
--
Vitaly
