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 95B96282F31 for ; Thu, 28 May 2026 14:51:27 +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=1779979888; cv=none; b=coQKmFBpgg38v6QylBZhH2bg/Yqoa6j9NeZ1G3s6hAun5ic/E2T4Oixa+H8RrikSdYCvAUBNwVgpoavOdUeGtTvMs7Mi9h04H20HfAxpuzAaZdxrhX0gohkEDOfYqVO4gnGghBBbNEqqbnFpgh8+UuleGg+8NmRImcudoKiHc0A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779979888; c=relaxed/simple; bh=tes9eETmhbrfgk7DfFhxjNPU/OcGWQZ/gxVtYb53dAs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tYcGgHLQmE8bvhN3ycuL3tl4oVhMoFDG4DmeIg+41zOP3//Dcl2r7bF/m1IDLb1DzI7/yk55asDs4xXLoLjIMpVbCc56AYOpBMgJfe4JET0nxEMwQ8lF/dO67oASt5j8UwuA1d3mgkKTsogdUc/aD2GoQRHyZqZ2TPLwcbFI6V8= 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=HQ+ecjef; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=EcyQZcyv; 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="HQ+ecjef"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="EcyQZcyv" Date: Thu, 28 May 2026 16:51:24 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1779979886; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tes9eETmhbrfgk7DfFhxjNPU/OcGWQZ/gxVtYb53dAs=; b=HQ+ecjefrhd3lKo7MeHDceYtACK026uCjbf8UALWbQ/+35vdGKaVpFiGU4woUFbHWXfBeM 5tjZ9jrXOQOoqaTQG5a/b6jHNqMiTqr0qqNlVydmxNAoPSwDt/oUZE0Vfe+jPgzwcapJMn aicr1TsHin+oCcoopW3W/6nELXTACXHoR82yyUmaoTociOHgmiSTu+3u1ReKsMTEkhALxT Gygk4jplKr+IHFFpLO8ECxXBZ+TWwrwDiebG3GhMk1iVpm96h1ju/uoFYsWfDpXrEBwrMA Zl2qgUgHzAYn5NJuptua0lMfoVZn2zQDFeBxtz371ZO09OHKFlrZoTGjajIFWQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1779979886; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tes9eETmhbrfgk7DfFhxjNPU/OcGWQZ/gxVtYb53dAs=; b=EcyQZcyvPwqkHd0bsycUUrYzpTPcKbm8V+X8RafeKTe+8lwAhygLrg9Uc9VH4m/j4HDMeE oxoP4RPvZDUcwWBA== From: Sebastian Andrzej Siewior To: Waiman Long Cc: Catalin Marinas , Will Deacon , Mark Rutland , Clark Williams , Steven Rostedt , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH] arm64/entry: Don't disable preemption in debug_exception_enter() with RT kernel Message-ID: <20260528145124.v9o6OcOc@linutronix.de> References: <20260519222524.886454-1-longman@redhat.com> <20260520061920.XCqBHe0x@linutronix.de> 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 Content-Transfer-Encoding: quoted-printable In-Reply-To: On 2026-05-20 17:01:00 [-0400], Waiman Long wrote: >=20 > On 5/20/26 2:19 AM, Sebastian Andrzej Siewior wrote: > > On 2026-05-19 18:25:24 [-0400], Waiman Long wrote: > > > Commit d8bb6718c4db ("arm64: Make debug exception handlers visible fr= om > > > RCU") introduces debug_exception_enter() and debug_exception_exit() > > > where preemption is explicitly disabled. With a PREEMPT_RT debug kern= el, > > > the following bug report can happen. > > =E2=80=A6 > >=20 > > What kernel is this? I have backport (which is being tested) for v6.6 > > and v6.12, the patches are from v6.17-rc1. >=20 > The kernel backtrace is produced using the latest v7.1-rc4 kernel. There = are > a number of changes to the debug_exception_enter() and > debug_exception_exit() functions over the years, but the preemption disab= le > code remains since its introduction in v5.3. Let me look at this again. > BTW, what v6.17-rc1 patches are you talking about? https://lore.kernel.org/all/20260528144825.850351-1-bigeasy@linutronix.de/ > -Longman Sebastian