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 8C718CD4F54 for ; Wed, 20 May 2026 11:24:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:Content-Type:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=s8BoFCt0pkUBMnLRpJ4UVI49v07JwiXpXVvsRBKBXi8=; b=Aa2vGqtKwUYDLB PlbQKhTGnyMS4/IaV17It+VK0xfN75uKW7f40DrjEX7bJqUoJAT4shJsnTymD8msZftwfoTJfcv+o 4d2wMgyeRyQKeJw56HFg778DhD5YFx3MhRE67c+c16WSh1T3lgArIyLG2oMlyVffw5p009emO6oK1 IAhycIvlC44za1kJ96prmGk+YLwOo0fPeAlOiKN2lElGUCF591lgLiloaob6aNWEhA/kUPZkbHOx6 v5fcPHBYB8XT0xQsJH9Q0GOqNDSvfUnuMKzaJCqV8JMamH5DiIxDAUIxLWeTTzULNTZZj/lhOduPX ecboWiPV4WSsAQa6mwnQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wPf1u-00000004RNN-2PTV; Wed, 20 May 2026 11:24:02 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wPf1s-00000004RMa-3eDP for linux-arm-kernel@lists.infradead.org; Wed, 20 May 2026 11:24:02 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1779276239; 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=s8BoFCt0pkUBMnLRpJ4UVI49v07JwiXpXVvsRBKBXi8=; b=bB2o1a2KIFIiKwBE3Z1zsrMtasLqz0KwBy9fRFrAqi2Ai/aCXGl2GeyT+Bk1Arw3j+kRmO jKD8GLzHKL2pepC47Lmkj+y6HcL8OoP/DQxL13qdevP5KT2SMN44lYG4H3cwDTaSnA142r QBBr84BHHPNOmcp8+OI6dveyvoEDlI0= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-517-J6PPBFReMm-ii0ZMEBLQ7w-1; Wed, 20 May 2026 07:23:55 -0400 X-MC-Unique: J6PPBFReMm-ii0ZMEBLQ7w-1 X-Mimecast-MFC-AGG-ID: J6PPBFReMm-ii0ZMEBLQ7w_1779276234 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0AA031956095; Wed, 20 May 2026 11:23:53 +0000 (UTC) Received: from localhost (unknown [10.22.64.8]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 4FBD630002E4; Wed, 20 May 2026 11:23:51 +0000 (UTC) Date: Wed, 20 May 2026 08:23:49 -0300 From: "Luis Claudio R. Goncalves" To: Sebastian Andrzej Siewior Subject: Re: [PATCH] arm64/entry: Don't disable preemption in debug_exception_enter() with RT kernel Message-ID: References: <20260519222524.886454-1-longman@redhat.com> <20260520061920.XCqBHe0x@linutronix.de> MIME-Version: 1.0 In-Reply-To: <20260520061920.XCqBHe0x@linutronix.de> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: J0-QtM5542ss-KKqLN2UzgWh6ZylmszNHOWr0soFoNo_1779276234 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260520_042400_976629_08D4C35D X-CRM114-Status: GOOD ( 11.83 ) 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: , Cc: Mark Rutland , Catalin Marinas , linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org, Steven Rostedt , linux-arm-kernel@lists.infradead.org, Waiman Long , Will Deacon , Clark Williams Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 20, 2026 at 08:19:20AM +0200, Sebastian Andrzej Siewior wrote: > On 2026-05-19 18:25:24 [-0400], Waiman Long wrote: > > Commit d8bb6718c4db ("arm64: Make debug exception handlers visible from > > RCU") introduces debug_exception_enter() and debug_exception_exit() > > where preemption is explicitly disabled. With a PREEMPT_RT debug kernel, > > the following bug report can happen. > … > > What kernel is this? I have backport (which is being tested) for v6.6 > and v6.12, the patches are from v6.17-rc1. Sebastian, hardware breakpoint and watchpoint handlers still call debug_exception_exit() and disable preemption on aarch64. That should happen on v7.1-rc4 indeed. The suggestion was to mimic what x86_64 does with notify_die() -> hw_breakpoint_exceptions_notify(). In ARM hw_breakpoint_exceptions_notify() is a stub that always returns NOTIFY_DONE. Luis > Sebastian > ---end quoted text---