netdev - [PATCH net-next v1] page_pool: avoid infinite loop to schedule delayed worker

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Message-Id: <20250210130953.26831-1-kerneljasonxing@gmail.com>
Date: Mon, 10 Feb 2025 21:09:53 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	hawk@...nel.org,
	ilias.apalodimas@...aro.org,
	horms@...nel.org
Cc: netdev@...r.kernel.org,
	Jason Xing <kerneljasonxing@...il.com>
Subject: [PATCH net-next v1] page_pool: avoid infinite loop to schedule delayed worker

If the buggy driver causes the inflight less than 0 [1] and warns
us in page_pool_inflight(), it means we should not expect the
whole page_pool to get back to work normally.

We noticed the kworker is waken up repeatedly and infinitely[1]
in production. If the page pool detect the error happening,
probably letting it go is a better way and do not flood the
var log messages. This patch mitigates the adverse effect.

[1]
[Mon Feb 10 20:36:11 2025] ------------[ cut here ]------------
[Mon Feb 10 20:36:11 2025] Negative(-51446) inflight packet-pages
...
[Mon Feb 10 20:36:11 2025] Call Trace:
[Mon Feb 10 20:36:11 2025]  page_pool_release_retry+0x23/0x70
[Mon Feb 10 20:36:11 2025]  process_one_work+0x1b1/0x370
[Mon Feb 10 20:36:11 2025]  worker_thread+0x37/0x3a0
[Mon Feb 10 20:36:11 2025]  kthread+0x11a/0x140
[Mon Feb 10 20:36:11 2025]  ? process_one_work+0x370/0x370
[Mon Feb 10 20:36:11 2025]  ? __kthread_cancel_work+0x40/0x40
[Mon Feb 10 20:36:11 2025]  ret_from_fork+0x35/0x40
[Mon Feb 10 20:36:11 2025] ---[ end trace ebffe800f33e7e34 ]---

Signed-off-by: Jason Xing <kerneljasonxing@...il.com>
---
 net/core/page_pool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 1c6fec08bc43..8e9f5801aabb 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -1167,7 +1167,7 @@ void page_pool_destroy(struct page_pool *pool)
 	page_pool_disable_direct_recycling(pool);
 	page_pool_free_frag(pool);
 
-	if (!page_pool_release(pool))
+	if (page_pool_release(pool) <= 0)
 		return;
 
 	page_pool_detached(pool);
-- 
2.43.5