kexec: update VMCOREINFO for compound_order/dtor
authorAtsushi Kumagai <ats-kumagai@wm.jp.nec.com>
Thu, 28 Apr 2016 23:18:18 +0000 (16:18 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 29 Apr 2016 02:34:04 +0000 (19:34 -0700)
commit8639a847b0e11f8d2daa3eafe15a9609c91fd357
tree7a7d9ff8fe22c2376eb193870ec26a38c44665ef
parentb75a2bf899b668b1d52de8846aafdbcf81349c73
kexec: update VMCOREINFO for compound_order/dtor

makedumpfile refers page.lru.next to get the order of compound pages for
page filtering.

However, now the order is stored in page.compound_order, hence
VMCOREINFO should be updated to export the offset of
page.compound_order.

The fact is, page.compound_order was introduced already in kernel 4.0,
but the offset of it was the same as page.lru.next until kernel 4.3, so
this was not actual problem.

The above can be said also for page.lru.prev and page.compound_dtor,
it's necessary to detect hugetlbfs pages.  Further, the content was
changed from direct address to the ID which means dtor.

The problem is that unnecessary hugepages won't be removed from a dump
file in kernels 4.4.x and later.  This means that extra disk space would
be consumed.  It's a problem, but not critical.

Signed-off-by: Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/kexec_core.c