netdev - [PATCH net 4/4] netfilter: conntrack: warn when cleanup is stuck

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Message-ID: <20251207010942.1672972-5-kuba@kernel.org>
Date: Sat,  6 Dec 2025 17:09:42 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	andrew+netdev@...n.ch,
	horms@...nel.org,
	pablo@...filter.org,
	fw@...len.de,
	netfilter-devel@...r.kernel.org,
	willemdebruijn.kernel@...il.com,
	kuniyu@...gle.com,
	Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net 4/4] netfilter: conntrack: warn when cleanup is stuck

nf_conntrack_cleanup_net_list() calls schedule() so it does not
show up as a hung task. Add an explicit check to make debugging
leaked skbs/conntack references more obvious.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 net/netfilter/nf_conntrack_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 0b95f226f211..d1f8eb725d42 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2487,6 +2487,7 @@ void nf_conntrack_cleanup_net(struct net *net)
 void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
 {
 	struct nf_ct_iter_data iter_data = {};
+	unsigned long start = jiffies;
 	struct net *net;
 	int busy;
 
@@ -2507,6 +2508,8 @@ void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
 			busy = 1;
 	}
 	if (busy) {
+		DEBUG_NET_WARN_ONCE(time_after(jiffies, start + 60 * HZ),
+				    "conntrack cleanup blocked for 60s");
 		schedule();
 		goto i_see_dead_people;
 	}
-- 
2.52.0