From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2E5794A8FD8 for ; Wed, 2 Sep 2026 16:56:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788368219; cv=none; b=jpEgGuJgwwhGqaPIzjURkqH+WQhaP5fG/isteFeqlcDvIBxjSZRmI12Jw2ooy7qeLdS5PbaH3YYLdB8PPN/NuvJbuzpFA4i5h2HB/FhvShzZj9LHaDf8VFspX8Zg39PwW0Ahe+GQywtL1WPVgePxxSzFtYEbbvkcIk/P5qiC7vc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788368219; c=relaxed/simple; bh=DN5KbZePw6JBSf5gJ1Gk6voIvhyzmKFHWMkFaN49J3E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ezPiETFT/PftGZQkON3A1rh4AYNQjcCqL9t67LY+agti2ENVShS7MtspdU+zXUeYuhBZdclc+39/TPjnwGqpIXd6ymfCqtI/cQ1SWj+7Z+McT/0w9ogXkSsMPmJHqg5KL/7YzTB08l8005rbsBsZamfoxE/z6SHg2LAZIdMHQDU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZhpPI8PL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZhpPI8PL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 991E71F000E9; Wed, 2 Sep 2026 16:56:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788368217; bh=u/9WYOn6nTCmf3XSaymTZiiNfVKKnWjGVtkZgKPcY+w=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ZhpPI8PLSQz/EoAgsByj1e5RL/+/fpdYN9l3BSlcLvS/j2OjRyy8ZxTePdstKvqtu A9EkqxPWHwclJGvlsPTZE+0a3iKVseF9b1/HebPXdqEbVJfLKAXvZcEq/5X+B2sI47 clswgi2/svh30zKzY+d3slzErRMD/8XfugBM6VWtPbVhrStkdZdDhCMeF3jz0RTwO1 jwNfDI+ROi2e5dMVSHwqDrXOYZmb7j4nXS5aP9uPy268aaIVt9IgMoNNqZfGfuXcB/ MP8cuddAM+QWhOdMb1t51QruLSKt12LeGQAoCTjMfIe2zPkxZKpvJXqHIPKrsSh1oM 9t4Lq6CccdDZQ== Message-ID: Date: Wed, 2 Sep 2026 18:56:54 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH mptcp-next 2/2] mptcp: pm: skip extra_subflows accounting on disconnected msk Content-Language: fr To: Tao Cui , mptcp@lists.linux.dev Cc: geliang@kernel.org, cuitao@kylinos.cn References: <20260831093206.689827-1-cui.tao@linux.dev> <20260831093206.689827-3-cui.tao@linux.dev> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Tao Cui, On 31/08/2026 11:32, Tao Cui wrote: > From: Tao Cui > > The WARN_ON_ONCE() guards added to the extra_subflows decrement sites > turn out to be reachable: > > mptcp_pm_data_reset() zeroes the counter with only the msk socket lock > held, while an MP_JOIN subflow can still sit in msk->join_list, its > reference already accounted by mptcp_pm_allow_new_subflow() under > pm->lock. If the socket gets disconnected(AF_UNSPEC) in that window, > mptcp_pm_data_reset() zeroes the counter, and the join list is flushed > later at release_sock() time: the leftover subflow then reaches > mptcp_pm_subflow_check_next() (or __mptcp_pm_close_subflow() for > kernel PM sockets) with the counter already at 0, firing the warning. > On panic_on_warn kernels this is a remotely triggerable panic, which > is worse than the silent wrap the guards replaced. > > Skip the PM accounting when the msk is already in TCP_CLOSE: in the > scenario above the state is set before the counters are cleared, and > once the msk is closed the accounting is not relevant anymore. Keep a > clamp and a rate-limited pr_warn() on the decrement sites instead, > to leave a trace of any imbalance we would still not know about. > > Fixes: e99c1ca89071 ("mptcp: pm: add WARN_ON_ONCE guards on extra_subflows underflow") > Link: https://github.com/multipath-tcp/mptcp_net-next/issues/629 This patch looks good to me, but could you please use the "Closes" tag for the last patch of the series closing this ticket, please? Cheers, Matt -- Sponsored by the NGI0 Core fund.