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.
[akpm@linux-foundation.org: use struct initializers]
Signed-off-by: Sergei Rogachev <rogachevsergei@gmail.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 9ab4a9b..0993f5f 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -59,20 +59,19 @@
void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
{
- struct page_ext *page_ext;
- struct stack_trace *trace;
+ struct page_ext *page_ext = lookup_page_ext(page);
+ struct stack_trace trace = {
+ .nr_entries = 0,
+ .max_entries = ARRAY_SIZE(page_ext->trace_entries),
+ .entries = &page_ext->trace_entries[0],
+ .skip = 3,
+ };
- 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);
+ 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);
}
@@ -84,6 +83,10 @@
int ret;
int pageblock_mt, page_mt;
char *kbuf;
+ struct stack_trace trace = {
+ .nr_entries = page_ext->nr_entries,
+ .entries = &page_ext->trace_entries[0],
+ };
kbuf = kmalloc(count, GFP_KERNEL);
if (!kbuf)
@@ -121,8 +124,7 @@
if (ret >= count)
goto err;
- ret += snprint_stack_trace(kbuf + ret, count - ret,
- &page_ext->trace, 0);
+ ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
if (ret >= count)
goto err;