linux-kernel - [PATCH 1/2] kexec: update VMCOREINFO for compound

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Date:	Tue, 1 Mar 2016 06:14:32 +0000
From:	Atsushi Kumagai <ats-kumagai@...jp.nec.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>
Subject: [PATCH 1/2] 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.

Signed-off-by: Atsushi Kumagai <ats-kumagai@...jp.nec.com>
---
 kernel/kexec_core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 8dc6591..7c0b61d 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1413,6 +1413,8 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_OFFSET(page, lru);
 	VMCOREINFO_OFFSET(page, _mapcount);
 	VMCOREINFO_OFFSET(page, private);
+	VMCOREINFO_OFFSET(page, compound_dtor);
+	VMCOREINFO_OFFSET(page, compound_order);
 	VMCOREINFO_OFFSET(pglist_data, node_zones);
 	VMCOREINFO_OFFSET(pglist_data, nr_zones);
 #ifdef CONFIG_FLAT_NODE_MEM_MAP
@@ -1445,8 +1447,8 @@ static int __init crash_save_vmcoreinfo_init(void)
 #ifdef CONFIG_X86
 	VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
 #endif
-#ifdef CONFIG_HUGETLBFS
-	VMCOREINFO_SYMBOL(free_huge_page);
+#ifdef CONFIG_HUGETLB_PAGE
+	VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR);
 #endif

 	arch_crash_save_vmcoreinfo();
-- 
2.7.2