From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3950CCD98DA for ; Mon, 15 Jun 2026 17:22:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=g36MIwpGYoz3X7VL1Yutn+HhGIx2EjVVLG9IrRo4XS8=; b=UhvFGo7yz5RWWETe1im2867iqU /4qF678dLb242NIiQclwWeDT98aYs0/fXrpNLP0od9ZpKeTfxeH6rCU13sSP3roizj/5stepgNvF/ 7f/SmDBNifGB7WC/dDKRdUEpN8LNCDdD+LM/cl9V/lHBobVx6D2j4Vb/1SUc3b9B0u2Byl5Lw6lZ8 /nk/4rICmZ2FyK0anAPe0TXDqgpqPyG2CaKhwddwHHYvH7zK2Ybs8A7gITScdlDl7ImxKneM+6KWU 86ES69IBastR7G1n7lfztrfYM2c8GLlNSzdATf0BZsvxlaXfjhzQibFy4NQOGpygES/Vml/j8yTDs Oy8T8wGw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wZB0o-0000000Ee2e-0VbQ; Mon, 15 Jun 2026 17:22:14 +0000 Received: from galois.linutronix.de ([2a0a:51c0:0:12e:550::1]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wZB0h-0000000Ee0i-2h7k for linux-arm-kernel@lists.infradead.org; Mon, 15 Jun 2026 17:22:12 +0000 Date: Mon, 15 Jun 2026 19:21:58 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1781544120; 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=g36MIwpGYoz3X7VL1Yutn+HhGIx2EjVVLG9IrRo4XS8=; b=AwdVrvNTMnPiP117pH+w8Yusw6Pu9fpqsyY/bfv0hfJ9glQiTBK7M5v6xyuI+/od5zUjAV Nwb/yR1D6G2D27VWA/9Ajka/728BGF5OzevCisU98XPgaznpZdmJgC3NDfyItFWFXoAsQr fvBW3s35VfsU2Hz8Q0I/qMwuBR/7UZP3wK0yG40bAJEzhc0dyxcECkreKSY9y8jNGEiBb6 gcYC3sI+LGSc3U6b27t17nyukhwU3FdWGytMtwCHNQTkY5GZsmfEPZJTiLt0b2y1HubbTZ yMCCZRtrMzS1zc5SLZE8KFrkw3GzwgQjnymC1/a0eBkOoXsbKSa9p/dcED9Asw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1781544120; 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=g36MIwpGYoz3X7VL1Yutn+HhGIx2EjVVLG9IrRo4XS8=; b=bF2Jx9DjIAugTGfzqoeBJPeJfR2Oft6+R/cw7JPECtOjFGNdrEoN16C4yoqQlIfbIArarO YvsEFaxd9OJCvuBQ== From: Sebastian Andrzej Siewior To: "Luis Claudio R. Goncalves" Cc: Waiman Long , 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: <20260615172158.AoVQ3Q3K@linutronix.de> References: <20260519222524.886454-1-longman@redhat.com> <20260520061920.XCqBHe0x@linutronix.de> <20260528145124.v9o6OcOc@linutronix.de> <20260528153554.vllN7_T9@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260615_102207_823915_F24685E6 X-CRM114-Status: GOOD ( 16.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2026-05-29 21:51:06 [-0300], Luis Claudio R. Goncalves wrote: > On Thu, May 28, 2026 at 05:35:54PM +0200, Sebastian Andrzej Siewior wrote: > > On 2026-05-28 16:51:24 [+0200], To Waiman Long wrote: > > > > 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 disable > > > > code remains since its introduction in v5.3. > > > > > > Let me look at this again. > > > > So how do you reproduce this? The calls within debug_exception_enter()/ > > exit() look harmless or I miss the big thing here. > > From your backtrace, you have brk_handler() and this is gone since > > commit 31575e11ecf7e ("arm64: debug: split brk64 exception entry") which > > is v6.17-rc1. I can use gdb with breakpoint handling. > > Sebastian, in the original series Ada provided a few tests, including the > two files I list below. Running that test in a v7.1-rc5 kernel with > PREEMPT_RT and DEBUG_ATOMIC_SLEEP enabled, I get this backtrace: This is a reminder to myself that I need to look at this since it does not look solved with the breakpoint patches. But this is also perf. Sebastian