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 6851A2D6638 for ; Wed, 30 Jul 2025 16:35:29 +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=1753893332; cv=none; b=sDECamtxuLsv18FHSZ/7c+KMA4si9aQAr0HIIZU9t6nBuaq6Bk15JfDRohDIJNHPeeErdopp7vrqH/TuNJugiL9sXWag5iy4kTNqW/R4XrOAu9A2/kUbeLuD6jBsqk/xyWxbjXffDlayugI9UsRTi0X2XJXpzO+tlOJvQW+GnXY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753893332; c=relaxed/simple; bh=6Rx5bCk0GBzKv3jiGxdoUSJNJ+IcX+VKB4kqJbtSBCg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JUIzNqgsAZnqmgLc7NJuy23BPcYWsRr54RQujYHochIz6LjRjSeNy6NHJniEU4D7v354/aN5+Gu6T1jIz6ReB/Vh7UEIFnBqbaGJlgl9QuoA/jZ2nDfrnRPDFznPnZhvKLmTOAHI096nhXWbRK0H7PMIMj0e7DVemUV9f7CZYCg= 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: by Chamillionaire.breakpoint.cc (Postfix, from userid 1003) id 3CD016035A; Wed, 30 Jul 2025 18:35:21 +0200 (CEST) Date: Wed, 30 Jul 2025 18:35:20 +0200 From: Florian Westphal To: Pablo Neira Ayuso Cc: netfilter-devel Subject: Re: [nf-next 0/2] netfilter: nf_tables: make set flush more resistant to memory pressure Message-ID: References: <20250704123024.59099-1-fw@strlen.de> Precedence: bulk X-Mailing-List: netfilter-devel@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: Pablo Neira Ayuso wrote: > > Yes, that part works, but we still need to kfree the elements after unlink. > > > > When commit phase does the unlink, the element becomes unreachable from > > the set. At this time, the DELSETELEM object keeps a pointer to the > > unlinked elements, and that allows us to kfree after synchronize_rcu > > from the worker. If we don't want DELSETELEM for flush, we need to > > provide the address to free by other means, e.g. stick a pointer into > > struct nft_set_ext. > > For the commit phase, I suggest to add a list of dying elements to the > transaction object. After unlinking the element from the (internal) > set data structure, add it to this transaction dying list so it > remains reachable to be released after the rcu grace period. Thats what I meant by 'stick a pointer into struct nft_set_ext'. Its awkward but I should be able to get the priv pointer back by doing the inverse of nft_set_elem_ext(). The cleaner solution would be to turn nft_elem_priv into a 'nft_elem_common', place a hlist_node into that and then use container_of(). But its too much code churn for my liking. So I'll extend each set element with a pointer and add a removed_elements hlist_head to struct nft_trans_elem. The transacion id isn't needed I think once that list exist: it provides the needed info to undo previous operations without the need to walk the set again. We can probably even rework struct nft_trans_elem to always use this pointer, even for inserts, and only use the struct nft_trans_one_elem elems[] member for elements that we update (no add or removal). But thats something for a later time.