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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>
This commit is contained in:
Sergei Rogachev 2015-02-11 15:28:34 -08:00 committed by Linus Torvalds
parent 740a5ddb0e
commit 94f759d62b
2 changed files with 15 additions and 13 deletions
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2
include/linux/page_ext.h
View File

@ -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
};

26
mm/page_owner.c
View File

@ -59,20 +59,19 @@ void __reset_page_owner(struct page *page, unsigned int order)
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 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
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 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
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;