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 5BEB1C44528 for ; Mon, 20 Jul 2026 07:26:46 +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-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc: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=UOIkjNoxbfIFYVHLI4yFssH6Y/D7YgIxGoQqmFG14oA=; b=lcoSzMGxxlSGe8Wml4rZyVRfad gPDlLUZcArg0DcU7Tcy5Yz1sWfm8WLtk2J0x/M7H5IrRkw2zaUeoy36ZVc77x6JuU9p/LV0T0Jfa6 xTpPeDpcX1dW2RHD0yoM/gesP87TBSc0Yd61c8UIP/IQdqxDwCBHUo5fe/qLYHogL7832MVY0bVA0 Hw9TdN/guU6SU7ZneMR8UzjLRjPViQrLelzEjgcLP9oEKKGX4HMSndG6f5fD4h3h/08KksO/LCoWl NAB2LGCyx0abRXt/Ihp0LNWhDCgPQ2zZcvp7CJ/NYovnLPFn2WA9yq8fYTDmjP1D9vcoN8GZnGTb5 AbcG2ZJw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wliOd-0000000659V-11Uh; Mon, 20 Jul 2026 07:26:39 +0000 Received: from galois.linutronix.de ([193.142.43.55]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wliOC-0000000655x-0Gy3 for linux-arm-kernel@lists.infradead.org; Mon, 20 Jul 2026 07:26:13 +0000 Date: Mon, 20 Jul 2026 09:26:06 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1784532368; 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=UOIkjNoxbfIFYVHLI4yFssH6Y/D7YgIxGoQqmFG14oA=; b=QJ/OLNIyW/TJH6J6PqTmIYtUt9lmVMlIdgree2nKfMNGTc36QnTnHmf+sKdvE027+YDb8M 1UQQpgFpcfcJ1MHRAktDNuoTd5WolIjay8KqgS2tyMu/09fD1PYaMTEYLXAEsF25IyRgAY UlLzkl1ZCqFBPHBl0Fc5jr88c5wdZY9ZxEnBQa6YwlfQKoLed31SMWKYMU8QbXbmgszL/i 4ogU+9lctCBtAriK35nHSaQxNdnUiFNaSnbhIO/NJB8Tc5r9OuZQ7p9DC7QA3Hvx2iRB+g LSEcFjdoJcJ4z8T0ovUjFlAbSWhkeE51tQT8uhOsSuNkN25Y3B5b1roLaHUpTA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1784532368; 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=UOIkjNoxbfIFYVHLI4yFssH6Y/D7YgIxGoQqmFG14oA=; b=7MJS/yYaGQqNlruweePnxz+qv2CAtkdQic4wCsA+gkGoVgGutUGPHgTgTXLeXKBaW9mZ0f y/l5ATAdtkpM4YAA== From: Sebastian Andrzej Siewior To: Karl Mehltretter Cc: Russell King , Arnd Bergmann , linux-rt-devel@lists.linux.dev, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] ARM: select HAVE_POSIX_CPU_TIMERS_TASK_WORK Message-ID: <20260720072606.8KxzuDAj@linutronix.de> References: <20260718214515.11275-1-kmehltretter@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20260718214515.11275-1-kmehltretter@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260720_002612_277675_77909EC0 X-CRM114-Status: UNSURE ( 8.22 ) X-CRM114-Notice: Please train this message. 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 2026-07-18 23:45:15 [+0200], Karl Mehltretter wrote: > Commit c6e61c06d606 ("ARM: 9463/1: Allow to enable RT") enabled PREEMPT_RT > on ARM but did not select HAVE_POSIX_CPU_TIMERS_TASK_WORK. This leaves > CONFIG_POSIX_CPU_TIMERS_TASK_WORK disabled, so CPU timers expire in hard > IRQ context. =E2=80=A6 > Fixes: c6e61c06d606 ("ARM: 9463/1: Allow to enable RT") > Assisted-by: Claude:claude-fable-5 > Signed-off-by: Karl Mehltretter Reviewed-by: Sebastian Andrzej Siewior > Found with a self-hosted syzkaller instance patched to fuzz kernels on > QEMU's versatilepb machine (ARM926EJ-S, ARMv5TE). Runtime-tested before > and after the change on that setup, and compile-tested mps2_defconfig > with PREEMPT_RT (NOMMU, CPU_V7M). I obviously got the rules confused while dropping the KVM patches. Sebastian