The patch titled
Subject: mm/page_owner.c: remove unnecessary stack_trace field
has been added to the -mm tree. Its filename is
mm-page_ext-remove-unnecessary-stack_trace-field.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_ext-remove-unnecessary-stack_trace-field.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_ext-remove-unnecessary-stack_trace-field.patch
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------------------------------------------------------
From: Sergei Rogachev <rogachevsergei@xxxxxxxxx>
Subject: mm/page_owner.c: remove unnecessary stack_trace field
Page owner uses the page_ext structure to keep meta-information for every
page in the system. The structure also contains a field of type 'struct
stack_trace', page owner uses this field during invocation of the function
save_stack_trace. It is easy to notice that keeping a copy of this
structure for every page in the system is very inefficiently in terms of
memory.
The patch removes this unnecessary field of page_ext and forces page owner
to use a stack_trace structure allocated on the stack.
Signed-off-by: Sergei Rogachev <rogachevsergei@xxxxxxxxx>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page_ext.h | 2 +-
mm/page_owner.c | 21 ++++++++++++---------
2 files changed, 13 insertions(+), 10 deletions(-)
diff -puN include/linux/page_ext.h~mm-page_ext-remove-unnecessary-stack_trace-field include/linux/page_ext.h
--- a/include/linux/page_ext.h~mm-page_ext-remove-unnecessary-stack_trace-field
+++ a/include/linux/page_ext.h
@@ -40,7 +40,7 @@ struct page_ext {
#ifdef CONFIG_PAGE_OWNER
unsigned int order;
gfp_t gfp_mask;
- struct stack_trace trace;
+ unsigned int nr_entries;
unsigned long trace_entries[8];
#endif
};
diff -puN mm/page_owner.c~mm-page_ext-remove-unnecessary-stack_trace-field mm/page_owner.c
--- a/mm/page_owner.c~mm-page_ext-remove-unnecessary-stack_trace-field
+++ a/mm/page_owner.c
@@ -60,19 +60,19 @@ void __reset_page_owner(struct page *pag
void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
{
struct page_ext *page_ext;
- struct stack_trace *trace;
+ struct stack_trace trace;
page_ext = lookup_page_ext(page);
- trace = &page_ext->trace;
- trace->nr_entries = 0;
- trace->max_entries = ARRAY_SIZE(page_ext->trace_entries);
- trace->entries = &page_ext->trace_entries[0];
- trace->skip = 3;
- save_stack_trace(&page_ext->trace);
+ trace.nr_entries = 0;
+ trace.max_entries = ARRAY_SIZE(page_ext->trace_entries);
+ trace.entries = &page_ext->trace_entries[0];
+ trace.skip = 3;
+ save_stack_trace(&trace);
page_ext->order = order;
page_ext->gfp_mask = gfp_mask;
+ page_ext->nr_entries = trace.nr_entries;
__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
}
@@ -83,6 +83,7 @@ print_page_owner(char __user *buf, size_
{
int ret;
int pageblock_mt, page_mt;
+ struct stack_trace trace;
char *kbuf;
kbuf = kmalloc(count, GFP_KERNEL);
@@ -121,8 +122,10 @@ print_page_owner(char __user *buf, size_
if (ret >= count)
goto err;
- ret += snprint_stack_trace(kbuf + ret, count - ret,
- &page_ext->trace, 0);
+ trace.nr_entries = page_ext->nr_entries;
+ trace.entries = &page_ext->trace_entries[0];
+
+ ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
if (ret >= count)
goto err;
_
Patches currently in -mm which might be from rogachevsergei@xxxxxxxxx are
mm-page_ext-remove-unnecessary-stack_trace-field.patch
mm-page_ext-remove-unnecessary-stack_trace-field-fix.patch
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