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On Aug 31, 2017 7:38 PM, Kyeongdon Kim [off-list ref] wrote:

There was a memory leak problem when we did stressful test
on Android device.
The root cause of this was from page_frag_cache alloc
and it was very hard to find out.

We add to count the page frag allocation and free with function call.
The gap between pgfrag_alloc and pgfrag_free is good to to calculate
for the amount of page.
The gap between pgfrag_alloc_calls and pgfrag_free_calls is for
sub-indicator.
They can see trends of memory usage during the test.
Without it, it's difficult to check page frag usage so I believe we
should add it.

Signed-off-by: Kyeongdon Kim <redacted>
---
include/linux/vm_event_item.h | 4 ++++
mm/page_alloc.c               | 9 +++++++--
mm/vmstat.c                   | 4 ++++
3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index d77bc35..75425d4 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h

@@ -110,6 +110,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,

SWAP_RA,
SWAP_RA_HIT,
#endif
+PGFRAG_ALLOC,
+PGFRAG_FREE,
+PGFRAG_ALLOC_CALLS,
+PGFRAG_FREE_CALLS,
NR_VM_EVENT_ITEMS
};

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index db2d25f..b3ddd76 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c

@@ -4322,6 +4322,7 @@ void __page_frag_cache_drain(struct page *page, unsigned int count)

free_hot_cold_page(page, false);
else
__free_pages_ok(page, order);
+__count_vm_events(PGFRAG_FREE, 1 << order);
}
}
EXPORT_SYMBOL(__page_frag_cache_drain);

@@ -4338,7 +4339,7 @@ void *page_frag_alloc(struct page_frag_cache *nc,

page = __page_frag_cache_refill(nc, gfp_mask);
if (!page)
return NULL;
-
+__count_vm_events(PGFRAG_ALLOC, 1 << compound_order(page));
#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
/* if size can vary use size else just use PAGE_SIZE */
size = nc->size;

@@ -4375,6 +4376,7 @@ void *page_frag_alloc(struct page_frag_cache *nc,

nc->pagecnt_bias--;
nc->offset = offset;
+__count_vm_event(PGFRAG_ALLOC_CALLS);

return nc->va + offset;
}

@@ -4387,8 +4389,11 @@ void page_frag_free(void *addr)

{
struct page *page = virt_to_head_page(addr);

-if (unlikely(put_page_testzero(page)))
+if (unlikely(put_page_testzero(page))) {
+__count_vm_events(PGFRAG_FREE, 1 << compound_order(page));
__free_pages_ok(page, compound_order(page));
+}
+__count_vm_event(PGFRAG_FREE_CALLS);
}
EXPORT_SYMBOL(page_frag_free);

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 4bb13e7..c00fe05 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c

@@ -1217,6 +1217,10 @@ const char * const vmstat_text[] = {

"swap_ra",
"swap_ra_hit",
#endif
+"pgfrag_alloc",
+"pgfrag_free",
+"pgfrag_alloc_calls",
+"pgfrag_free_calls",
#endif /* CONFIG_VM_EVENTS_COUNTERS */
};
#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
-- 
2.6.2