From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f202.google.com (mail-qk1-f202.google.com [209.85.222.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 969BF36308D for ; Tue, 19 May 2026 09:55:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779184543; cv=none; b=AgJhdQlSGOW/9BsfjC9hqHnehUtbTdvLK4jiizoUBY3HM+LCb+krMSAkuYUzB+yi5UqRjAWpnkksWLGWlTlTSxdmRmoDbHzpg8FDFdfVN+mSi8ClRsdzrvR3ULiPKuU2S3uCC1dzwKPfG5g+4JWH5ZDHCZit4LSxjekaRJnwnbg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779184543; c=relaxed/simple; bh=NidIrej7UvcItlv/QGIDkIVHZGZk1wkHjVJPh0+r+lw=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=ftPFbgtiSknlPpnUHeIrBY3lPacr26oHpfLdsA2CGxZE3rdxSDmpoy91A0xzFszFsEQidcK5x3de0FwI3QYYd6N6HTf+VbmH4DbXjk4IZMH0hW+BJ2K5IJ1gP6iBEB0b1HQYArMyQbeu47rvj7WO0TEZP427N2rofM0msD+hDPE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=g4kc4e17; arc=none smtp.client-ip=209.85.222.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="g4kc4e17" Received: by mail-qk1-f202.google.com with SMTP id af79cd13be357-90fbc9782c9so645144185a.0 for ; Tue, 19 May 2026 02:55:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1779184541; x=1779789341; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=UL5sa6moiS69L9aQq8Atm/ndGvM9Sc4sCh2Q07gTeeI=; b=g4kc4e175mASZeqO0S0rZn2Ye2OJb1xyIXxev8+Taubrtk7AN5Ob3AcBSiATfFpU6N yST2sKgEBSNmfiPg+S7IIGmatEE9ky1b3mTCHcodHHN3z5TRIY714YnrGT+x0wuaEAZv S1fOvz144GwTcxEHf058ylgPMCKqiC3shgBkHDOY5Y76JfPw0/rQTa3bekTJTqBVyHFp 1PGZJBRgk9xtiMlqTEIucD+T5jmQextk6GvL5qSR2hu2h7eAqPdLrmVuj2RWsSKPUwvo hZ8vXcDoGjoxXgjDGm5BqnDZ2Ae8Onco2OkV9I2lcHdRzE3LIkIG9puPMfj1qCNbJrZ7 ugIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779184541; x=1779789341; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=UL5sa6moiS69L9aQq8Atm/ndGvM9Sc4sCh2Q07gTeeI=; b=V45OXXAkE+VEQnheCnDmB4Hbc0gVw7Q8npkJGX0TXbimlbrMLn94nLndkm5vISDmkA uwh5IpC4KtZUjLyr2VrZ+57VcqjnpMbfk6c4dmiGpOooDBRgcgt9ahxY8dqYLHVztlTH oOijKsEGueBerc3il/Gm+/Gc3Fd6co0xHjTZU5TE1LMSXbDQPtF4Kp3HvyJEvAot46jA kQpzZVvauMTnM2c/WkQrPJ+7b1BmSY/QYsVE+IpNTtWU3vBE6bvMPIoqTTvWfr9iIxiT q/znDJLFBDWBt0lmlYwxfqRbEIKsAw3MKTZj4wiRG/MVS0ZLK2eeynPwcyFCogGBB3Gz zCLQ== X-Forwarded-Encrypted: i=1; AFNElJ++dDLSbpq18XFNziuMz6ir89u9NriA6oMEZ1cYJVboNx5ZegTT9Icj8NEBQFpdNy4X9uoio+4=@vger.kernel.org X-Gm-Message-State: AOJu0YzFs96EgyHefv6Ua/B95PiHDoBr3/ndImPGsRnfp8g6iBiDsYAd gbakEqgN3zuRH+fKxKyEyI6kCTE7I6No+9r8ttmiGBeDpgJme0XTJKkreog6dtnCeUpM1sx0ohD nVkiXVQCmHKaDEg== X-Received: from qkax10-n2.prod.google.com ([2002:a05:620a:224a:20b0:90d:7dbb:8d4c]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:a05:620a:2950:b0:8ef:f1c0:ab7f with SMTP id af79cd13be357-911ce524059mr2772821685a.24.1779184541336; Tue, 19 May 2026 02:55:41 -0700 (PDT) Date: Tue, 19 May 2026 09:55:40 +0000 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.54.0.563.g4f69b47b94-goog Message-ID: <20260519095540.2643318-1-edumazet@google.com> Subject: [PATCH net-next] net: bridge: remove stale rcu_barrier() in br_multicast_dev_del() From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet , Nikolay Aleksandrov , Ido Schimmel Content-Type: text/plain; charset="UTF-8" This rcu_barrier() came from a time call_rcu() calls were used in net/bridge/br_multicast.c. Now kfree_rcu() is there, we can remove this problematic rcu_barrier() which causes extreme RTNL pressure in many syzbot reports. INFO: task syz-executor:77945 is blocked on a mutex likely owned by task kworker/u1024:5:36537. task:kworker/u1024:5 state:D stack:24616 pid:36537 tgid:36537 ppid:2 task_flags:0x4208060 flags:0x00080000 last_sleep:612797637337 Workqueue: netns cleanup_net Call Trace: [] context_switch+0xf2a/0x1730 kernel/sched/core.c:6483 [] __schedule+0x1133/0x43a0 kernel/sched/core.c:8411 [] __schedule_loop kernel/sched/core.c:8514 [inline] [] schedule+0xab/0x260 kernel/sched/core.c:8529 [] schedule_timeout+0xc3/0x2b0 kernel/time/sleep_timeout.c:75 [] do_wait_for_common kernel/sched/completion.c:100 [inline] [] __wait_for_common kernel/sched/completion.c:121 [inline] [] wait_for_common kernel/sched/completion.c:132 [inline] [] wait_for_completion+0x2c7/0x5d0 kernel/sched/completion.c:153 [] rcu_barrier+0x49f/0x620 kernel/rcu/tree.c:3888 [] br_multicast_dev_del+0x303/0x350 net/bridge/br_multicast.c:4459 [] br_dev_uninit+0x1c/0x40 net/bridge/br_device.c:157 [] unregister_netdevice_many_notify+0x1c1c/0x2300 net/core/dev.c:12599 [] ops_exit_rtnl_list net/core/net_namespace.c:187 [inline] [] ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248 Signed-off-by: Eric Dumazet --- Cc: Nikolay Aleksandrov Cc: Ido Schimmel --- net/bridge/br_multicast.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 49ceea3ff9742d3043ac605d656b7fcf37dbcb96..8efa3add5d47508fb2b032ff6238ffbbabfd27ad 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -4453,8 +4453,6 @@ void br_multicast_dev_del(struct net_bridge *br) br_multicast_ctx_deinit(&br->multicast_ctx); br_multicast_gc(&deleted_head); cancel_work_sync(&br->mcast_gc_work); - - rcu_barrier(); } int br_multicast_set_router(struct net_bridge_mcast *brmctx, unsigned long val) -- 2.54.0.563.g4f69b47b94-goog