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 13B93CAC582 for ; Tue, 9 Sep 2025 17:27:15 +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=HAFQuoEKspwLRd/H9Kd3b5OWJp44kKNa44M7zP9QiWg=; b=yXKKOMS0S1ya0Pblj0iJxyDTFn XfxSnd0sfKvX8Q1ZoQLl+34ZKX53GqzYgJFEouM26BjLfsfr2ZWvKbts9jFwjG0GdOdgJfudwj4S4 FKa78BHW1No8TQ+Nf5o47TDHjOvg70NILPo3cDMSo9F490mOh8bXAvc+85vKDHtCJWib/q3++KCHC af7fj/uLCcGTWxlG0q+HWdOCe6iRlN1RwEErRAJJHfHBeCpYWBSF1Y1hFBC/7lF4iDO75k0G/Xwn8 iQQfdEeKY/nFS06zFkmRgA5G+YYZCdxlpUXe9xf58KY0nvX5QK5Ya/5qZRcNqVfkBKXW6wUPG7uLA BDwB4dGA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uw27W-000000096tC-1EWM; Tue, 09 Sep 2025 17:27:06 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uw1l0-00000008jDr-1G6J for linux-arm-kernel@lists.infradead.org; Tue, 09 Sep 2025 17:03:50 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id AEB5260224; Tue, 9 Sep 2025 17:03:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5D7AC4CEF4; Tue, 9 Sep 2025 17:03:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757437429; bh=0ePioIJRedWiKF0fn+IJE4meuWisJGQBNojm9/VTE8k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Q3+ngas/LmfCKgPZgS169nXNhfUMi1tMAVKGAMExa9X/38EsL7MfulBUMkwfZZoTe EF6V/mhI34Ox2QTO9s9jc+vlIXF1iuc7UwoqLnxIiQguFuweWprRw9rDy817jTfk4M +22dYEsWWFJ4SmAw6+NxxjrOaTJgppaHnzoQ6sq0bZ0+t4O/hmpBdDCb7sk0blDggh GMPw7BByEmf61rxXpP8B25vPJW51PtIaDk4RgueiveFEskvx7pnKkwrWw3TkkflV8B JJxHYM0pcgdmUCgJCUMDnq5/i3ijSytnVEEweecUgcNsdSmlPYQcO2xSxFkJcaRF+c 0HJX8bWWEnw5w== Date: Tue, 9 Sep 2025 18:03:44 +0100 From: Will Deacon To: Krzysztof Kozlowski Cc: Mostafa Saleh , linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, alim.akhtar@samsung.com, Peter Griffin , =?iso-8859-1?Q?Andr=E9?= Draszik Subject: Re: [PATCH] soc: samsung: exynos-pmu: Fix for CONFIG_DEBUG_PREEMPT Message-ID: References: <20250905162446.88987-1-smostafa@google.com> <19a6f296-eb40-49cf-9571-2d7964cd3313@kernel.org> <84332e77-cfd2-4090-a3c0-114a9eb5422a@kernel.org> <52222467-4fc0-4a53-9682-a935ec8f1a44@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52222467-4fc0-4a53-9682-a935ec8f1a44@kernel.org> 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 Tue, Sep 09, 2025 at 05:43:16PM +0200, Krzysztof Kozlowski wrote: > On 09/09/2025 12:15, Will Deacon wrote: > > Krzysztof, > > > > On Sat, Sep 06, 2025 at 09:07:02AM +0200, Krzysztof Kozlowski wrote: > >> On 05/09/2025 19:43, Mostafa Saleh wrote: > >>>>> > >>>>> As this value is only read once, it doesn't require to be stable, so > >>>> > >>>> Why it does not need to be stable? Onlining wrong CPU number is not > >>>> desired... > >>>> > >>>>> just use "raw_smp_processor_id" instead. > >>>> > >>>> You might be just hiding some other real issue, because above stacktrace > >>>> is from gs101_cpuhp_pmu_online() which IRQs disabled and preemption > >>>> disabled. Provide analysis of the warning, instead of just making it > >>>> disappear. > >>> > >>> Not sure I understand, how is preemption disabled? that wouldn't fire > >>> in that case. > >> > >> Because there is explicit preempt_disable(). > > > > Where do you see that? > > I did look at the code. > > All the calls I saw (including calltrace from commit msg) were under raw > spinlock and raw spinlock does: > > preempt_disable(); The backtrace doesn't contain a raw spinlock. As Peter subsequently pointed out, the reported issue has been fixed in linux-next and there's a raw spinlock there but since the report is from vanilla -rc4, it doesn't have that fix. Will