[PATCH net-next v1 11/11] page_pool: add tracepoints for page_pool with details need by XDP

Jesper Dangaard Brouer
2019-06-13T18:29:03Z

The xdp tracepoints for mem id disconnect don't carry information about, why
it was not safe_to_remove. The tracepoint page_pool:page_pool_inflight in
this patch can be used for extract this info for further debugging.

This patchset also adds tracepoint for the pages_state_* release/hold
transitions, including a pointer to the page. This can be used for stats
about in-flight pages, or used to debug page leakage via keeping track of
page pointer and combining this with kprobe for __put_page().

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
include/trace/events/page_pool.h | 87 ++++++++++++++++++++++++++++++++++++++
net/core/net-traces.c | 4 ++
net/core/page_pool.c | 9 +++-
3 files changed, 99 insertions(+), 1 deletion(-)
create mode 100644 include/trace/events/page_pool.h

diff --git a/include/trace/events/page_pool.h b/include/trace/events/page_pool.h
new file mode 100644
index 000000000000..47b5ee880aa9
--- /dev/null
+++ b/include/trace/events/page_pool.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM page_pool
+
+#if !defined(_TRACE_PAGE_POOL_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_PAGE_POOL_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+#include <net/page_pool.h>
+
+TRACE_EVENT(page_pool_inflight,
+
+ TP_PROTO(const struct page_pool *pool,
+ s32 inflight, u32 hold, u32 release),
+
+ TP_ARGS(pool, inflight, hold, release),
+
+ TP_STRUCT__entry(
+ __field(const struct page_pool *, pool)
+ __field(s32, inflight)
+ __field(u32, hold)
+ __field(u32, release)
+ ),
+
+ TP_fast_assign(
+ __entry->pool = pool;
+ __entry->inflight = inflight;
+ __entry->hold = hold;
+ __entry->release = release;
+ ),
+
+ TP_printk("page_pool=%p inflight=%d hold=%u release=%u",
+ __entry->pool, __entry->inflight, __entry->hold, __entry->release)
+);
+
+TRACE_EVENT(page_pool_state_release,
+
+ TP_PROTO(const struct page_pool *pool,
+ const struct page *page, u32 release),
+
+ TP_ARGS(pool, page, release),
+
+ TP_STRUCT__entry(
+ __field(const struct page_pool *, pool)
+ __field(const struct page *, page)
+ __field(u32, release)
+ ),
+
+ TP_fast_assign(
+ __entry->pool = pool;
+ __entry->page = page;
+ __entry->release = release;
+ ),
+
+ TP_printk("page_pool=%p page=%p release=%u",
+ __entry->pool, __entry->page, __entry->release)
+);
+
+TRACE_EVENT(page_pool_state_hold,
+
+ TP_PROTO(const struct page_pool *pool,
+ const struct page *page, u32 hold),
+
+ TP_ARGS(pool, page, hold),
+
+ TP_STRUCT__entry(
+ __field(const struct page_pool *, pool)
+ __field(const struct page *, page)
+ __field(u32, hold)
+ ),
+
+ TP_fast_assign(
+ __entry->pool = pool;
+ __entry->page = page;
+ __entry->hold = hold;
+ ),
+
+ TP_printk("page_pool=%p page=%p hold=%u",
+ __entry->pool, __entry->page, __entry->hold)
+);
+
+#endif /* _TRACE_PAGE_POOL_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/net/core/net-traces.c b/net/core/net-traces.c
index 470b179d599e..283ddb2dbc7d 100644
--- a/net/core/net-traces.c
+++ b/net/core/net-traces.c
@@ -43,6 +43,10 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(fdb_delete);
EXPORT_TRACEPOINT_SYMBOL_GPL(br_fdb_update);
#endif

+#if IS_ENABLED(CONFIG_PAGE_POOL)
+#include <trace/events/page_pool.h>
+#endif
+
#include <trace/events/neigh.h>
EXPORT_TRACEPOINT_SYMBOL_GPL(neigh_update);
EXPORT_TRACEPOINT_SYMBOL_GPL(neigh_update_done);
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 42c3b0a5a259..f55ab055d543 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -4,6 +4,7 @@
* Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
* Copyright (C) 2016 Red Hat, Inc.
*/
+
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
@@ -14,6 +15,8 @@
#include <linux/page-flags.h>
#include <linux/mm.h> /* for __put_page() */

+#include <trace/events/page_pool.h>
+
static int page_pool_init(struct page_pool *pool,
const struct page_pool_params *params)
{
@@ -156,6 +159,8 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
/* Track how many pages are held 'in-flight' */
pool->pages_state_hold_cnt++;

+ trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
+
/* When page just alloc'ed is should/must have refcnt 1. */
return page;
}
@@ -191,7 +196,7 @@ static s32 page_pool_inflight(struct page_pool *pool)

distance = _distance(hold_cnt, release_cnt);

- /* TODO: Add tracepoint here */
+ trace_page_pool_inflight(pool, distance, hold_cnt, release_cnt);
return distance;
}

@@ -222,6 +227,8 @@ static void __page_pool_clean_page(struct page_pool *pool,
page->dma_addr = 0;
skip_dma_unmap:
atomic_inc(&pool->pages_state_release_cnt);
+ trace_page_pool_state_release(pool, page,
+ atomic_read(&pool->pages_state_release_cnt));
}

/* unmap the page and clean our state */