Memory overhead of 4MB is reduced by storing gfp_mask in stackdepot along
with stacktrace. Stackdepot memory usage increased by ~100kb for 4GB of RAM.
Page owner logs from dmesg:
Before patch:
allocated 20971520 bytes of page_ext
After patch:
allocated 16777216 bytes of page_ext
Signed-off-by: Sai Charan Sane <s.charan@xxxxxxxxxxx>
---
mm/page_owner.c | 61 +++++++++++++++++++++++++++++++++++----------------------
1 file changed, 38 insertions(+), 23 deletions(-)
diff --git a/mm/page_owner.c b/mm/page_owner.c
index addcbb2..01856ed 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -16,13 +16,14 @@
/*
* TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
* to use off stack temporal storage
+ * 16 stacktrace entries + 1 gfp mask
*/
-#define PAGE_OWNER_STACK_DEPTH (16)
+#define PAGE_OWNER_STACK_DEPTH (16 + 1)
+#define MAX_TRACE_ENTRIES(entries) (ARRAY_SIZE(entries) - 1)
struct page_owner {
unsigned short order;
short last_migrate_reason;
- gfp_t gfp_mask;
depot_stack_handle_t handle;
};
@@ -57,10 +58,11 @@ static bool need_page_owner(void)
static __always_inline depot_stack_handle_t create_dummy_stack(void)
{
- unsigned long entries[4];
+ unsigned long entries[8];
unsigned int nr_entries;
- nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
+ nr_entries = stack_trace_save(entries, MAX_TRACE_ENTRIES(entries), 0);
+ entries[nr_entries++] = 0;
return stack_depot_save(entries, nr_entries, GFP_KERNEL);
}
@@ -134,7 +136,7 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
depot_stack_handle_t handle;
unsigned int nr_entries;
- nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
+ nr_entries = stack_trace_save(entries, MAX_TRACE_ENTRIES(entries), 2);
/*
* We need to check recursion here because our request to
@@ -147,6 +149,8 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
if (check_recursive_alloc(entries, nr_entries, _RET_IP_))
return dummy_handle;
+ entries[nr_entries++] = flags;
+
handle = stack_depot_save(entries, nr_entries, flags);
if (!handle)
handle = failure_handle;
@@ -155,14 +159,13 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
}
static inline void __set_page_owner_handle(struct page_ext *page_ext,
- depot_stack_handle_t handle, unsigned int order, gfp_t gfp_mask)
+ depot_stack_handle_t handle, unsigned int order)
{
struct page_owner *page_owner;
page_owner = get_page_owner(page_ext);
page_owner->handle = handle;
page_owner->order = order;
- page_owner->gfp_mask = gfp_mask;
page_owner->last_migrate_reason = -1;
__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
@@ -178,7 +181,7 @@ noinline void __set_page_owner(struct page *page, unsigned int order,
return;
handle = save_stack(gfp_mask);
- __set_page_owner_handle(page_ext, handle, order, gfp_mask);
+ __set_page_owner_handle(page_ext, handle, order);
}
void __set_page_owner_migrate_reason(struct page *page, int reason)
@@ -220,7 +223,6 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage)
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;
@@ -248,6 +250,10 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
unsigned long count[MIGRATE_TYPES] = { 0, };
int pageblock_mt, page_mt;
int i;
+ unsigned long *entries;
+ unsigned int nr_entries;
+ depot_stack_handle_t handle;
+ gfp_t gfp_mask;
/* Scan block by block. First and last block may be incomplete */
pfn = zone->zone_start_pfn;
@@ -298,8 +304,15 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
continue;
page_owner = get_page_owner(page_ext);
- page_mt = gfpflags_to_migratetype(
- page_owner->gfp_mask);
+ handle = READ_ONCE(page_owner->handle);
+ if (!handle) {
+ pr_alert("page_owner info is not active (free page?)\n");
+ return;
+ }
+
+ nr_entries = stack_depot_fetch(handle, &entries);
+ gfp_mask = entries[--nr_entries];
+ page_mt = gfpflags_to_migratetype(gfp_mask);
if (pageblock_mt != page_mt) {
if (is_migrate_cma(pageblock_mt))
count[MIGRATE_MOVABLE]++;
@@ -329,23 +342,26 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
unsigned long *entries;
unsigned int nr_entries;
char *kbuf;
+ gfp_t gfp_mask;
count = min_t(size_t, count, PAGE_SIZE);
kbuf = kmalloc(count, GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
+ nr_entries = stack_depot_fetch(handle, &entries);
+ gfp_mask = entries[--nr_entries];
+
ret = snprintf(kbuf, count,
"Page allocated via order %u, mask %#x(%pGg)\n",
- page_owner->order, page_owner->gfp_mask,
- &page_owner->gfp_mask);
+ page_owner->order, gfp_mask, &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_owner->gfp_mask);
+ page_mt = gfpflags_to_migratetype(gfp_mask);
ret += snprintf(kbuf + ret, count - ret,
"PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
pfn,
@@ -357,7 +373,6 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
if (ret >= count)
goto err;
- nr_entries = stack_depot_fetch(handle, &entries);
ret += stack_trace_snprint(kbuf + ret, count - ret, entries, nr_entries, 0);
if (ret >= count)
goto err;
@@ -401,21 +416,21 @@ void __dump_page_owner(struct page *page)
}
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)) {
+ handle = READ_ONCE(page_owner->handle);
+ if (!handle) {
pr_alert("page_owner info is not active (free page?)\n");
return;
}
- handle = READ_ONCE(page_owner->handle);
- if (!handle) {
+ nr_entries = stack_depot_fetch(handle, &entries);
+ gfp_mask = entries[--nr_entries];
+ 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;
}
- nr_entries = stack_depot_fetch(handle, &entries);
pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
stack_trace_print(entries, nr_entries, 0);
@@ -562,7 +577,7 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
continue;
/* Found early allocated page */
- __set_page_owner_handle(page_ext, early_handle, 0, 0);
+ __set_page_owner_handle(page_ext, early_handle, 0);
count++;
}
cond_resched();
--
1.9.1
