+ kexec-export-offsetpagecompound_head-to-find-out-compound-tail-page.patch added to -mm tree

+ kexec-export-offsetpagecompound_head-to-find-out-compound-tail-page.patch added to -mm tree

[akpm]

The patch titled
     Subject: kexec: export OFFSET(page.compound_head) to find out compound tail page
has been added to the -mm tree.  Its filename is
     kexec-export-offsetpagecompound_head-to-find-out-compound-tail-page.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/kexec-export-offsetpagecompound_head-to-find-out-compound-tail-page.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/kexec-export-offsetpagecompound_head-to-find-out-compound-tail-page.patch

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------------------------------------------------------
From: Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>
Subject: kexec: export OFFSET(page.compound_head) to find out compound tail page

PageAnon() always look at head page to check PAGE_MAPPING_ANON and tail
page's page->mapping has just a poisoned data since commit 1c290f642101e6.

If makedumpfile checks page->mapping of an compound tail page to
distinguish anonymous page as usual, it must fail in newer kernel.  So
it's necessary to export OFFSET(page.compound_head) to avoid checking
compound tail pages.

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>
---

 kernel/kexec_core.c |    1 +
 1 file changed, 1 insertion(+)

diff -puN kernel/kexec_core.c~kexec-export-offsetpagecompound_head-to-find-out-compound-tail-page kernel/kexec_core.c
--- a/kernel/kexec_core.c~kexec-export-offsetpagecompound_head-to-find-out-compound-tail-page
+++ a/kernel/kexec_core.c
@@ -1417,6 +1417,7 @@ static int __init crash_save_vmcoreinfo_
 	VMCOREINFO_OFFSET(page, private);
 	VMCOREINFO_OFFSET(page, compound_dtor);
 	VMCOREINFO_OFFSET(page, compound_order);
+	VMCOREINFO_OFFSET(page, compound_head);
 	VMCOREINFO_OFFSET(pglist_data, node_zones);
 	VMCOREINFO_OFFSET(pglist_data, nr_zones);
 #ifdef CONFIG_FLAT_NODE_MEM_MAP
_

Patches currently in -mm which might be from ats-kumagai@wm.jp.nec.com are

kexec-update-vmcoreinfo-for-compound_order-dtor.patch
kexec-export-offsetpagecompound_head-to-find-out-compound-tail-page.patch