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Subject[PATCH 5/5] mm/page_owner: don't define fields on struct page_ext by hard-coding
Date
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

There is a memory waste problem if we define field on struct page_ext
by hard-coding. Entry size of struct page_ext includes the size of
those fields even if it is disabled at runtime. Now, extra memory request
at runtime is possible so page_owner don't need to define it's own fields
by hard-coding.

This patch removes hard-coded define and uses extra memory for storing
page_owner information in page_owner. Most of code are just mechanical
changes.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
include/linux/page_ext.h | 6 ----
mm/page_owner.c | 83 +++++++++++++++++++++++++++++++++---------------
2 files changed, 58 insertions(+), 31 deletions(-)

diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 179bdc4..9298c39 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -44,12 +44,6 @@ enum page_ext_flags {
*/
struct page_ext {
unsigned long flags;
-#ifdef CONFIG_PAGE_OWNER
- unsigned int order;
- gfp_t gfp_mask;
- int last_migrate_reason;
- depot_stack_handle_t handle;
-#endif
};

extern void pgdat_page_ext_init(struct pglist_data *pgdat);
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 14c8e65..59d7490 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -17,6 +17,13 @@
*/
#define PAGE_OWNER_STACK_DEPTH (16)

+struct page_owner {
+ unsigned int order;
+ gfp_t gfp_mask;
+ int last_migrate_reason;
+ depot_stack_handle_t handle;
+};
+
static bool page_owner_disabled = true;
DEFINE_STATIC_KEY_FALSE(page_owner_inited);

@@ -85,10 +92,16 @@ static void init_page_owner(void)
}

struct page_ext_operations page_owner_ops = {
+ .size = sizeof(struct page_owner),
.need = need_page_owner,
.init = init_page_owner,
};

+static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
+{
+ return (void *)page_ext + page_owner_ops.offset;
+}
+
void __reset_page_owner(struct page *page, unsigned int order)
{
int i;
@@ -155,14 +168,16 @@ noinline void __set_page_owner(struct page *page, unsigned int order,
gfp_t gfp_mask)
{
struct page_ext *page_ext = lookup_page_ext(page);
+ struct page_owner *page_owner;

if (unlikely(!page_ext))
return;

- page_ext->handle = save_stack(gfp_mask);
- page_ext->order = order;
- page_ext->gfp_mask = gfp_mask;
- page_ext->last_migrate_reason = -1;
+ page_owner = get_page_owner(page_ext);
+ page_owner->handle = save_stack(gfp_mask);
+ page_owner->order = order;
+ page_owner->gfp_mask = gfp_mask;
+ page_owner->last_migrate_reason = -1;

__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
}
@@ -170,21 +185,26 @@ noinline void __set_page_owner(struct page *page, unsigned int order,
void __set_page_owner_migrate_reason(struct page *page, int reason)
{
struct page_ext *page_ext = lookup_page_ext(page);
+ struct page_owner *page_owner;
+
if (unlikely(!page_ext))
return;

- page_ext->last_migrate_reason = reason;
+ page_owner = get_page_owner(page_ext);
+ page_owner->last_migrate_reason = reason;
}

void __split_page_owner(struct page *page, unsigned int order)
{
int i;
struct page_ext *page_ext = lookup_page_ext(page);
+ struct page_owner *page_owner;

if (unlikely(!page_ext))
return;

- page_ext->order = 0;
+ page_owner = get_page_owner(page_ext);
+ page_owner->order = 0;
for (i = 1; i < (1 << order); i++)
__copy_page_owner(page, page + i);
}
@@ -193,14 +213,18 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage)
{
struct page_ext *old_ext = lookup_page_ext(oldpage);
struct page_ext *new_ext = lookup_page_ext(newpage);
+ struct page_owner *old_page_owner, *new_page_owner;

if (unlikely(!old_ext || !new_ext))
return;

- new_ext->order = old_ext->order;
- new_ext->gfp_mask = old_ext->gfp_mask;
- new_ext->last_migrate_reason = old_ext->last_migrate_reason;
- new_ext->handle = old_ext->handle;
+ old_page_owner = get_page_owner(old_ext);
+ new_page_owner = get_page_owner(new_ext);
+ new_page_owner->order = old_page_owner->order;
+ new_page_owner->gfp_mask = old_page_owner->gfp_mask;
+ new_page_owner->last_migrate_reason =
+ old_page_owner->last_migrate_reason;
+ new_page_owner->handle = old_page_owner->handle;

/*
* We don't clear the bit on the oldpage as it's going to be freed
@@ -219,6 +243,7 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, pg_data_t *pgdat,
{
struct page *page;
struct page_ext *page_ext;
+ struct page_owner *page_owner;
unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
unsigned long end_pfn = pfn + zone->spanned_pages;
unsigned long count[MIGRATE_TYPES] = { 0, };
@@ -269,14 +294,16 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, pg_data_t *pgdat,
if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
continue;

- page_mt = gfpflags_to_migratetype(page_ext->gfp_mask);
+ page_owner = get_page_owner(page_ext);
+ page_mt = gfpflags_to_migratetype(
+ page_owner->gfp_mask);
if (pageblock_mt != page_mt) {
count[pageblock_mt]++;

pfn = block_end_pfn;
break;
}
- pfn += (1UL << page_ext->order) - 1;
+ pfn += (1UL << page_owner->order) - 1;
}
}

@@ -289,7 +316,7 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, pg_data_t *pgdat,

static ssize_t
print_page_owner(char __user *buf, size_t count, unsigned long pfn,
- struct page *page, struct page_ext *page_ext,
+ struct page *page, struct page_owner *page_owner,
depot_stack_handle_t handle)
{
int ret;
@@ -309,15 +336,15 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,

ret = snprintf(kbuf, count,
"Page allocated via order %u, mask %#x(%pGg)\n",
- page_ext->order, page_ext->gfp_mask,
- &page_ext->gfp_mask);
+ page_owner->order, page_owner->gfp_mask,
+ &page_owner->gfp_mask);

if (ret >= count)
goto err;

/* Print information relevant to grouping pages by mobility */
pageblock_mt = get_pageblock_migratetype(page);
- page_mt = gfpflags_to_migratetype(page_ext->gfp_mask);
+ page_mt = gfpflags_to_migratetype(page_owner->gfp_mask);
ret += snprintf(kbuf + ret, count - ret,
"PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
pfn,
@@ -334,10 +361,10 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
if (ret >= count)
goto err;

- if (page_ext->last_migrate_reason != -1) {
+ if (page_owner->last_migrate_reason != -1) {
ret += snprintf(kbuf + ret, count - ret,
"Page has been migrated, last migrate reason: %s\n",
- migrate_reason_names[page_ext->last_migrate_reason]);
+ migrate_reason_names[page_owner->last_migrate_reason]);
if (ret >= count)
goto err;
}
@@ -360,6 +387,7 @@ err:
void __dump_page_owner(struct page *page)
{
struct page_ext *page_ext = lookup_page_ext(page);
+ struct page_owner *page_owner;
unsigned long entries[PAGE_OWNER_STACK_DEPTH];
struct stack_trace trace = {
.nr_entries = 0,
@@ -375,7 +403,9 @@ void __dump_page_owner(struct page *page)
pr_alert("There is not page extension available.\n");
return;
}
- gfp_mask = page_ext->gfp_mask;
+
+ page_owner = get_page_owner(page_ext);
+ gfp_mask = page_owner->gfp_mask;
mt = gfpflags_to_migratetype(gfp_mask);

if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
@@ -383,7 +413,7 @@ void __dump_page_owner(struct page *page)
return;
}

- handle = READ_ONCE(page_ext->handle);
+ handle = READ_ONCE(page_owner->handle);
if (!handle) {
pr_alert("page_owner info is not active (free page?)\n");
return;
@@ -391,12 +421,12 @@ void __dump_page_owner(struct page *page)

depot_fetch_stack(handle, &trace);
pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
- page_ext->order, migratetype_names[mt], gfp_mask, &gfp_mask);
+ page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
print_stack_trace(&trace, 0);

- if (page_ext->last_migrate_reason != -1)
+ if (page_owner->last_migrate_reason != -1)
pr_alert("page has been migrated, last migrate reason: %s\n",
- migrate_reason_names[page_ext->last_migrate_reason]);
+ migrate_reason_names[page_owner->last_migrate_reason]);
}

static ssize_t
@@ -405,6 +435,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
unsigned long pfn;
struct page *page;
struct page_ext *page_ext;
+ struct page_owner *page_owner;
depot_stack_handle_t handle;

if (!static_branch_unlikely(&page_owner_inited))
@@ -454,11 +485,13 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
continue;

+ page_owner = get_page_owner(page_ext);
+
/*
* Access to page_ext->handle isn't synchronous so we should
* be careful to access it.
*/
- handle = READ_ONCE(page_ext->handle);
+ handle = READ_ONCE(page_owner->handle);
if (!handle)
continue;

@@ -466,7 +499,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
*ppos = (pfn - min_low_pfn) + 1;

return print_page_owner(buf, count, pfn, page,
- page_ext, handle);
+ page_owner, handle);
}

return 0;
--
1.9.1
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