From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (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 BAB303597B; Sun, 1 Feb 2026 01:45:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769910323; cv=pass; b=Yw5er7UJOQXmeFkxoBNl6DLVLvn3ZywKd5MwaiX1ZejCPpGSPi2yto2tVF/NffcCbBGTQLSQmceAvXm7Ffnu40ewSi8JuaDM1H7HkaIqqEO+8c0Qr82FOJVD9k2CUB1bbHARZLcTSDEfeXqzOEMkAtrB8CIIlFioIQHpOV0Ggzg= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769910323; c=relaxed/simple; bh=+BE/aOCCJtfEvwl/rY/BaFAqJGwQ3CQ/5FKlrXU36Us=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: MIME-Version:Content-Type; b=QGXGgpsLsXx5sd6TbEfQCIA5L+bF1+3+92VRuqIiNGVP0eWdxRkzxhHWGPauMlF5rf7CvLaCNxmP/rF2UHR00WKlnrjiugPtTfetGd+KrgjHsZTHGna4GUXe0f5YGXSN0V93duIb+wQxjnwIrpTFu2UEWziwgnsWxPmLMsdO1g0= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=linux.beauty; spf=pass smtp.mailfrom=linux.beauty; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b=dtTXRY3C; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=linux.beauty Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.beauty Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b="dtTXRY3C" ARC-Seal: i=1; a=rsa-sha256; t=1769910269; cv=none; d=zohomail.com; s=zohoarc; b=m0IOtmd5YqZsEJ/pwodTe27kB+pIBoW4WbFCt4/2HBk2Tyt9/b2eRTnA1uPRavHsUryo5b1JYTEe9SLAbB0crrmMEudEl4TsJkKO3IR5978gq57qSeuDs2L7H+cP1GYnCcww/2fzHY5/GKlZ44sjiVOe1BsH0rIylZ+vuyfbA4o= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1769910269; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=IlG1n9BLDZ09VGbQUqKZBipsjvO2o1DnNBZKvwfyDwk=; b=Ojpcf78xHG+VH9H+S4tL7P1V/m269NAUOSjTzoIIM8q3h4W7dlpZfjFcsLkPiaF/01V1fAHoYWQL9PXFBMa3XLP+/XVrMA0lmtDrMDwyHolxh7K7yAGgMPw4Ub64txwvuhmI8/tXMTRrdlgesIbrau1FQHNZpzUZC7wCS0x/Sag= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=linux.beauty; spf=pass smtp.mailfrom=me@linux.beauty; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1769910269; s=zmail; d=linux.beauty; i=me@linux.beauty; h=Date:Date:From:From:To:To:Cc:Cc:Message-ID:In-Reply-To:References:Subject:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-Id:Reply-To; bh=IlG1n9BLDZ09VGbQUqKZBipsjvO2o1DnNBZKvwfyDwk=; b=dtTXRY3C6JqHvcRiViY4SIotEiRzuDmvKpN0smf6mdUy9EbPUx+17cTp+tB7l6DW DNIEIc9ABwfrnYBUmYjbx81UkTHolhiu/FCJFUhI2zhKpFifEfGHkycX4AieV/g94sw hKoQa9hMSTG/7r3FxOhs0BZ49csvDBxX4Emz6H2Y= Received: from mail.zoho.com by mx.zohomail.com with SMTP id 1769910267415394.81945402914016; Sat, 31 Jan 2026 17:44:27 -0800 (PST) Date: Sun, 01 Feb 2026 09:44:27 +0800 From: Li Chen To: "Jakub Kicinski" Cc: "Jonathan Corbet" , "Pasha Tatashin" , "Mike Rapoport" , "Pratyush Yadav" , "Eric Dumazet" , "Neal Cardwell" , "Kuniyuki Iwashima" , "David S. Miller" , "David Ahern" , "Paolo Abeni" , "Simon Horman" , "Andrew Morton" , "Borislav Petkov" , "Randy Dunlap" , "Pawan Gupta" , "Petr Mladek" , "Feng Tang" , "Kees Cook" , "Li RongQing" , "Arnd Bergmann" , "Askar Safin" , "Frank van der Linden" , "linux-doc" , "linux-kernel" , "netdev" Message-ID: <19c16df6e07.5d6555571430461.7492468111934043630@linux.beauty> In-Reply-To: <20260130170533.257db5fb@kernel.org> References: <20260130145122.368748-1-me@linux.beauty> <20260130145122.368748-4-me@linux.beauty> <20260130170533.257db5fb@kernel.org> Subject: Re: [PATCH v1 3/3] liveupdate: suppress TCP RST during post-kexec restore window Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Importance: Medium User-Agent: Zoho Mail X-Mailer: Zoho Mail Hi Jakub, > On Fri, 30 Jan 2026 22:51:19 +0800 Li Chen wrote: > > During a kexec-based live update, userspace may restore established TCP > > connections after the new kernel has booted (e.g. via CRIU). Any packet > > arriving for a not-yet-restored socket will hit the no-socket path and > > trigger a TCP RST, causing the peer to immediately drop the connection. > > Can you not add a filter to simply drop those packets until workload is > running again? It'd actually be less racy than this hac^w patch ... > Thanks for the suggestion. When you say "add a filter", do you mean installing a temporary drop rule (nftables/iptables/tc) in the network domain which does not get rebooted by kexec (e.g. LB/ToR/host firewall), so packets never reach the new kernel until the workload is restored and ready? If you meant a filter inside the kexec'ed kernel, I'm worried it won't cover the critical window: kexec resets the ruleset, so we'd have to install the drop rule extremely early (initramfs) before any packets hit the no-socket path, which still seems inherently racy. If the expectation is to drain/blackhole traffic externally and re-enable it once the workload is running again, I can rework the series to keep only the restore-window tracking plus a clear "restore done" control plane, and rely on the external filter for the data plane. Regards Li