From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [91.216.245.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C2F981CDFDA for ; Tue, 1 Oct 2024 19:36:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.216.245.30 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727811378; cv=none; b=n8wAH7V/he3Z3L4uUak61p3B1M9BbkqEimqFF/YSF+iPcD03WzrLeYGlNH0UXAoUrnCfGWCbCS62hNngTQd2l+ELi5KFb6B3/sGDG+omPKgLbtvrhjgRFozSNIMCltcwS6tQZvCpozG3+pRyisJJi4fiXuwFSR81zc0lEbxS62g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727811378; c=relaxed/simple; bh=7qgvZCGl9L0K8NsxKwAwANVYLKAycFej1Rrdno8rvsw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fjX76WtrJ3FVTCrorVAittiB+Pu+qEWLLJIimrFQWgGWwS31gOtoYw5TiFnni05NyCTkyyxvtMDyICR1ykCg18GRAst6ZtJ39VXoA2S3i9x6ubIkJfuyPjIX0VbazpY+HszC977A9vwicGjTDELhjEsTJqH9bX+ySyjRcFK0T7Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de; spf=pass smtp.mailfrom=strlen.de; arc=none smtp.client-ip=91.216.245.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=strlen.de Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1svifG-0002qm-9O; Tue, 01 Oct 2024 21:36:06 +0200 Date: Tue, 1 Oct 2024 21:36:06 +0200 From: Florian Westphal To: Ben Greear Cc: netdev , kent.overstreet@linux.dev, surenb@google.com, pablo@netfilter.org Subject: Re: nf-nat-core: allocated memory at module unload. Message-ID: <20241001193606.GA10530@breakpoint.cc> References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Ben Greear wrote: [ CCing codetag folks ] > Hello, > > I see this splat in 6.11.0 (plus a single patch to fix vrf xmit deadlock). > > Is this a known issue? Is it a serious problem? Not known to me. Looks like an mm (rcu)+codetag problem. > ------------[ cut here ]------------ > net/netfilter/nf_nat_core.c:1114 module nf_nat func:nf_nat_register_fn has 256 allocated at module unload > WARNING: CPU: 1 PID: 10421 at lib/alloc_tag.c:168 alloc_tag_module_unload+0x22b/0x3f0 > Modules linked in: nf_nat(-) btrfs ufs qnx4 hfsplus hfs minix vfat msdos fat ... > Hardware name: Default string Default string/SKYBAY, BIOS 5.12 08/04/2020 > RIP: 0010:alloc_tag_module_unload+0x22b/0x3f0 > codetag_unload_module+0x19b/0x2a0 > ? codetag_load_module+0x80/0x80 > ? up_write+0x4f0/0x4f0 "Well, yes, but actually no." At this time, kfree_rcu() has been called on all 4 objects. Looks like kfree_rcu no longer cares even about rcu_barrier(), and there is no kvfree_rcu_barrier() in 6.11. The warning goes away when I replace kfree_rcu with call_rcu+kfree plus rcu_barrier in module exit path. But I don't think its the right thing to do. (referring to nf_nat_unregister_fn(), kfree_rcu(priv, rcu_head);). Reproducer: unshare -n iptables-nft -t nat -A PREROUTING -p tcp grep nf_nat /proc/allocinfo # will list 4 allocations rmmod nft_chain_nat rmmod nf_nat # will WARN. Without rmmod, the 4 allocations go away after a few seconds, grep will no longer list them and then rmmod won't splat.