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mm/page_owner: don't define fields on struct page_ext by hard-coding
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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.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Joonsoo Kim <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@JoonsooKim @torvalds
JoonsooKim authored and torvalds committed Oct 8, 2016
1 parent 980ac16 commit 9300d8d
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Showing 2 changed files with 58 additions and 31 deletions.
6 changes: 0 additions & 6 deletions include/linux/page_ext.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down
83 changes: 58 additions & 25 deletions mm/page_owner.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,13 @@
*/
#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);

Expand Down Expand Up @@ -86,10 +93,16 @@ 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;
Expand Down Expand Up @@ -156,36 +169,43 @@ 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);
}

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);
}
Expand All @@ -194,14 +214,18 @@ 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
Expand All @@ -220,6 +244,7 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
{
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, };
Expand Down Expand Up @@ -270,7 +295,9 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
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) {
if (is_migrate_cma(pageblock_mt))
count[MIGRATE_MOVABLE]++;
Expand All @@ -280,7 +307,7 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
pfn = block_end_pfn;
break;
}
pfn += (1UL << page_ext->order) - 1;
pfn += (1UL << page_owner->order) - 1;
}
}

Expand All @@ -293,7 +320,7 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,

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;
Expand All @@ -313,15 +340,15 @@ 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,
Expand All @@ -338,10 +365,10 @@ 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;
}
Expand All @@ -364,6 +391,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
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,
Expand All @@ -379,28 +407,30 @@ 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)) {
pr_alert("page_owner info is not active (free page?)\n");
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;
}

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
Expand All @@ -409,6 +439,7 @@ 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))
Expand Down Expand Up @@ -458,19 +489,21 @@ 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;

/* Record the next PFN to read in the file offset */
*ppos = (pfn - min_low_pfn) + 1;

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

return 0;
Expand Down

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