From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 01402347BBD; Mon, 1 Jun 2026 06:58:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780297097; cv=none; b=lJTQXp2TCx+lN4oIOycMjm9pYk56oJKpfAolGPlN/KyowTjUqeG7cYg8+r7+IY4ugrvpA7czS4Q4ZnY2b6fFDPP4UhW7BzvNm+8DCFqqiczAKhyLJ5NUhkYhaus5yEjFE3xtmYCHef8hFg9/uhiO3RsLpq/PsDa7szCL5MXXONg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780297097; c=relaxed/simple; bh=yJy0CmnIxJjAFp2xvW0lH2ZU1wwcYRyC/5qf0dtOaLU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Z8eGHmq90KuXCMkVCPnC91orW5yYk59xMWW9Rr/kCDeX9RacMUe/Co1j+uScU1ja/FTJgzIrVmjzMIpepIK6GNuVUdlZixrOP5juEBSxOloGK66Uqinn1y9oNHChXuALaHQzrvmYlzRJzVEC2ck6w6fWGC1UHp5b3b+TNToDcvE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=zORcKruJ; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=0FcOzPlV; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="zORcKruJ"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="0FcOzPlV" Date: Mon, 1 Jun 2026 08:58:13 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1780297094; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=yJy0CmnIxJjAFp2xvW0lH2ZU1wwcYRyC/5qf0dtOaLU=; b=zORcKruJ9QJOtW4JL1Pm23rr8Nn7859O839uqpFCiRaLhnVpt3vH5A45v3oD0GwU5zEKFp 5KoiJpX7ERkDuyC63RVc863tn+FhxNrbtSYDFuc9XRyXQKe098LP/duwnZ6B+DMlsG+va6 gBMoGhERg8d+Qryv1wRUdCzFR/nyy6IWl7NJxOE3QEiINHdZOIDw93MtX4O/A0Tg2Zl+Ot VMBejWMXFzpGnedfK2hJIGqYdCc5QQYg+xqIBqUXRnN3N8J2NkblzOca2Dhpg2ox4QKjDM vZpyeqt2EeCZ++90Cu00ZypywIJUdXYBZVkgN7cYdaIuJqTu3S3KeSTLp8qWZA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1780297094; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=yJy0CmnIxJjAFp2xvW0lH2ZU1wwcYRyC/5qf0dtOaLU=; b=0FcOzPlVIato7qS/odBjpYZVeForAreWqj7U1P+j8gvuU5FR/47koS4F5+qJ3QtgejkaMS lLIMMvRIEAawgHAA== From: Sebastian Andrzej Siewior To: "Matthieu Baerts (NGI0)" Cc: Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Florian Westphal , netdev@vger.kernel.org, mptcp@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, stable@vger.kernel.org, Clark Williams , Steven Rostedt , Hannes Reinecke , linux-rt-devel@lists.linux.dev Subject: Re: [PATCH net 09/10] mptcp: pm: avoid sleeping while holding rcu_read_lock Message-ID: <20260601065813.Z8V8Tb6d@linutronix.de> References: <20260601-net-mptcp-misc-fixes-7-1-rc7-v1-0-a5ae7791754b@kernel.org> <20260601-net-mptcp-misc-fixes-7-1-rc7-v1-9-a5ae7791754b@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260601-net-mptcp-misc-fixes-7-1-rc7-v1-9-a5ae7791754b@kernel.org> On 2026-06-01 13:10:05 [+1000], Matthieu Baerts (NGI0) wrote: > sk_stop_timer_sync() calls del_timer_sync(), which spin-waits for the There is no del_timer_sync() > timer callback to complete on non-RT kernels. But on PREEMPT_RT, it can > sleep. Sleeping inside an RCU read-side critical section might trigger a > lockdep splat. It can not sleep. timer_delete_sync() does not sleep. It can block on spinlock_t and schedule but this is okay within a RCU read section. Do you have a report for this? Sebastian