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Message-Id: <20130315200411.59edc3c7af0ffafdef2a9d4b@mxc.nes.nec.co.jp>
Date: Fri, 15 Mar 2013 20:04:11 +0900
From: Atsushi Kumagai <kumagai-atsushi@....nes.nec.co.jp>
To: iamjoonsoo.kim@....com, ebiederm@...ssion.com
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, anderson@...hat.com, vgoyal@...hat.com,
lliubbo@...il.com, penberg@...nel.org, kexec@...ts.infradead.org,
js1304@...il.com
Subject: Re: [PATCH v2 7/8] mm, vmalloc: export vmap_area_list, instead of
vmlist
Hello,
On Tue, 12 Mar 2013 23:43:48 -0700
ebiederm@...ssion.com (Eric W. Biederman) wrote:
> Joonsoo Kim <iamjoonsoo.kim@....com> writes:
>
> > From: Joonsoo Kim <js1304@...il.com>
> >
> > Although our intention is to unexport internal structure entirely,
> > but there is one exception for kexec. kexec dumps address of vmlist
> > and makedumpfile uses this information.
> >
> > We are about to remove vmlist, then another way to retrieve information
> > of vmalloc layer is needed for makedumpfile. For this purpose,
> > we export vmap_area_list, instead of vmlist.
>
> That seems entirely reasonable to me. Usage by kexec should not limit
> the evoluion of the kernel especially usage by makedumpfile.
>
> Atsushi Kumagai can you make makedumpfile work with this change?
Sure! I'm going to work with this change in the next version.
But, I noticed that necessary information is missed in this patch,
and sorry for too late reply.
Both OFFSET(vmap_area.va_start) and OFFSET(vmap_area.list) are
necessary to get vmalloc_start value from vmap_area_list, but
they aren't exported in this patch.
I understand that the policy of this patch series "to unexport
internal structure entirely", although the information is necessary
for makedumpfile.
Additionally, OFFSET(vm_struct.addr) is no longer used, should be
removed. It was added for the same purpose as vmlist in the commit
below.
commit acd99dbf54020f5c80b9aa2f2ea86f43cb285b02
Author: Ken'ichi Ohmichi <oomichi@....nes.nec.co.jp>
Date: Sat Oct 18 20:28:30 2008 -0700
kdump: add vmlist.addr to vmcoreinfo for x86 vmalloc translation.
To sum it up, I would like to push the patch below.
Thanks
Atsushi Kumagai
--
From: Atsushi Kumagai <kumagai-atsushi@....nes.nec.co.jp>
Date: Fri, 15 Mar 2013 14:19:28 +0900
Subject: [PATCH] kexec, vmalloc: Export additional information of
vmalloc layer.
Now, vmap_area_list is exported as VMCOREINFO for makedumpfile
to get the start address of vmalloc region (vmalloc_start).
The address which contains vmalloc_start value is represented as
below:
vmap_area_list.next - OFFSET(vmap_area.list) + OFFSET(vmap_area.va_start)
However, both OFFSET(vmap_area.va_start) and OFFSET(vmap_area.list)
aren't exported as VMCOREINFO.
So, this patch exports them externally with small cleanup.
Signed-off-by: Atsushi Kumagai <kumagai-atsushi@....nes.nec.co.jp>
---
include/linux/vmalloc.h | 12 ++++++++++++
kernel/kexec.c | 3 ++-
mm/vmalloc.c | 11 -----------
3 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 8a25f90..62e0354 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -4,6 +4,7 @@
#include <linux/spinlock.h>
#include <linux/init.h>
#include <asm/page.h> /* pgprot_t */
+#include <linux/rbtree.h>
struct vm_area_struct; /* vma defining user mapping in mm_types.h */
@@ -35,6 +36,17 @@ struct vm_struct {
const void *caller;
};
+struct vmap_area {
+ unsigned long va_start;
+ unsigned long va_end;
+ unsigned long flags;
+ struct rb_node rb_node; /* address sorted rbtree */
+ struct list_head list; /* address sorted list */
+ struct list_head purge_list; /* "lazy purge" list */
+ struct vm_struct *vm;
+ struct rcu_head rcu_head;
+};
+
/*
* Highlevel APIs for driver use
*/
diff --git a/kernel/kexec.c b/kernel/kexec.c
index d9bfc6c..5db0148 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1527,7 +1527,8 @@ static int __init crash_save_vmcoreinfo_init(void)
VMCOREINFO_OFFSET(free_area, free_list);
VMCOREINFO_OFFSET(list_head, next);
VMCOREINFO_OFFSET(list_head, prev);
- VMCOREINFO_OFFSET(vm_struct, addr);
+ VMCOREINFO_OFFSET(vmap_area, va_start);
+ VMCOREINFO_OFFSET(vmap_area, list);
VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);
log_buf_kexec_setup();
VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 151da8a..72043d6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -249,17 +249,6 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
#define VM_LAZY_FREEING 0x02
#define VM_VM_AREA 0x04
-struct vmap_area {
- unsigned long va_start;
- unsigned long va_end;
- unsigned long flags;
- struct rb_node rb_node; /* address sorted rbtree */
- struct list_head list; /* address sorted list */
- struct list_head purge_list; /* "lazy purge" list */
- struct vm_struct *vm;
- struct rcu_head rcu_head;
-};
-
static DEFINE_SPINLOCK(vmap_area_lock);
/* Export for kexec only */
LIST_HEAD(vmap_area_list);
--
1.8.0.2
--
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