From a3a476cb65a411e3fe1f1792779d5dd09927fe91 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Thu, 20 Nov 2025 14:56:55 -0500 Subject: [PATCH] net: netpoll: flush skb pool during cleanup [ Upstream commit 6c59f16f1770481a6ee684720ec55b1e38b3a4b2 ] The netpoll subsystem maintains a pool of 32 pre-allocated SKBs per instance, but these SKBs are not freed when the netpoll user is brought down. This leads to memory waste as these buffers remain allocated but unused. Add skb_pool_flush() to properly clean up these SKBs when netconsole is terminated, improving memory efficiency. Signed-off-by: Breno Leitao Link: https://patch.msgid.link/20241114-skb_buffers_v2-v3-2-9be9f52a8b69@debian.org Signed-off-by: Jakub Kicinski Stable-dep-of: 49c8d2c1f94c ("net: netpoll: fix incorrect refcount handling causing incorrect cleanup") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/core/netpoll.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/net/core/netpoll.c b/net/core/netpoll.c index ee7af71b7b10..f053141b8896 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -538,6 +538,14 @@ static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr) return -1; } +static void skb_pool_flush(struct netpoll *np) +{ + struct sk_buff_head *skb_pool; + + skb_pool = &np->skb_pool; + skb_queue_purge_reason(skb_pool, SKB_CONSUMED); +} + int netpoll_parse_options(struct netpoll *np, char *opt) { char *cur=opt, *delim; @@ -786,7 +794,7 @@ put_noaddr: err = __netpoll_setup(np, ndev); if (err) - goto put; + goto flush; rtnl_unlock(); /* Make sure all NAPI polls which started before dev->npinfo @@ -797,6 +805,8 @@ put_noaddr: return 0; +flush: + skb_pool_flush(np); put: DEBUG_NET_WARN_ON_ONCE(np->dev); if (ip_overwritten) @@ -844,6 +854,8 @@ void __netpoll_cleanup(struct netpoll *np) call_rcu(&npinfo->rcu, rcu_cleanup_netpoll_info); } else RCU_INIT_POINTER(np->dev->npinfo, NULL); + + skb_pool_flush(np); } EXPORT_SYMBOL_GPL(__netpoll_cleanup);