[net-next v1 PATCH 4/4] page_pool: extend tracepoint to also include the page PFN

Jesper Dangaard Brouer
2019-11-15T15:06:27Z

The MM tracepoint for page free (called kmem:mm_page_free) doesn't provide
the page pointer directly, instead it provides the PFN (Page Frame Number).
This is annoying when writing a page_pool leak detector in BPF.

This patch change page_pool tracepoints to also provide the PFN.
The page pointer is still provided to allow other kinds of
troubleshooting from BPF.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
include/trace/events/page_pool.h | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/trace/events/page_pool.h b/include/trace/events/page_pool.h
index ee7f1aca7839..2f2a10e8eb56 100644
--- a/include/trace/events/page_pool.h
+++ b/include/trace/events/page_pool.h
@@ -8,6 +8,7 @@
#include <linux/types.h>
#include <linux/tracepoint.h>

+#include <trace/events/mmflags.h>
#include <net/page_pool.h>

TRACE_EVENT(page_pool_release,
@@ -49,16 +50,18 @@ TRACE_EVENT(page_pool_state_release,
__field(const struct page_pool *, pool)
__field(const struct page *, page)
__field(u32, release)
+ __field(unsigned long, pfn)
),

TP_fast_assign(
__entry->pool = pool;
__entry->page = page;
__entry->release = release;
+ __entry->pfn = page_to_pfn(page);
),

- TP_printk("page_pool=%p page=%p release=%u",
- __entry->pool, __entry->page, __entry->release)
+ TP_printk("page_pool=%p page=%p pfn=%lu release=%u",
+ __entry->pool, __entry->page, __entry->pfn, __entry->release)
);

TRACE_EVENT(page_pool_state_hold,
@@ -72,16 +75,18 @@ TRACE_EVENT(page_pool_state_hold,
__field(const struct page_pool *, pool)
__field(const struct page *, page)
__field(u32, hold)
+ __field(unsigned long, pfn)
),

TP_fast_assign(
__entry->pool = pool;
__entry->page = page;
__entry->hold = hold;
+ __entry->pfn = page_to_pfn(page);
),

- TP_printk("page_pool=%p page=%p hold=%u",
- __entry->pool, __entry->page, __entry->hold)
+ TP_printk("page_pool=%p page=%p pfn=%lu hold=%u",
+ __entry->pool, __entry->page, __entry->pfn, __entry->hold)
);

#endif /* _TRACE_PAGE_POOL_H */