Commit 94f759d6 authored by Sergei Rogachev's avatar Sergei Rogachev Committed by Linus Torvalds
Browse files

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: default avatarSergei Rogachev <rogachevsergei@gmail.com>
Acked-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 740a5ddb

include/linux/page_ext.h

+1 −1
Original line number Diff line number Diff line
@@ -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

};

mm/page_owner.c

+14 −12
Original line number Diff line number Diff line
@@ -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;



	page_ext = lookup_page_ext(page);

	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,

	};



	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;

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