From 8639a847b0e11f8d2daa3eafe15a9609c91fd357 Mon Sep 17 00:00:00 2001
From: Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>
Date: Thu, 28 Apr 2016 16:18:18 -0700
Subject: 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 | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
(limited to 'kernel/kexec_core.c')
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 8d34308ea449..cbbb4c724149 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1415,6 +1415,8 @@ 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
@@ -1447,8 +1449,8 @@ 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();
--
cgit v1.2.3-70-g09d2
From d7f53518f713d3d9bf5ed150f943853fb94e7473 Mon Sep 17 00:00:00 2001
From: Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>
Date: Thu, 28 Apr 2016 16:18:21 -0700
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 1c290f642101
("mm: sanitize page->mapping for tail pages").
If makedumpfile checks page->mapping of a 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.
The problem is that unnecessary hugepages won't be removed from a dump
file in kernels 4.5.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 | 1 +
1 file changed, 1 insertion(+)
(limited to 'kernel/kexec_core.c')
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index cbbb4c724149..1391d3ee3b86 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1417,6 +1417,7 @@ static int __init crash_save_vmcoreinfo_init(void)
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
--
cgit v1.2.3-70-g09d2