From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 60ED0281341; Thu, 4 Dec 2025 20:42:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764880978; cv=none; b=oDmOsYNQ8KmTp3/rtkp+V0r4ea0G1bmaXqkA3VXPoEqJqZip6Z60ddiPThwdPxM4vujjpsYfV9nXroGkHjajNZSUUBoTiqUKSfVF8P+VkcjtT0SCCwDMVN54TQCyANTTmMbiIYtlNcDqRMJA6XmPWCQLf4TfvYsU/2tEGggfgVw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764880978; c=relaxed/simple; bh=L7d1qiM8xYz9QN18vNQm2ZFkGv4gdjDPj0W/v44zrYc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VQquy2/FBnhaOLpe/2A6IlEEbJ5YXT5VT8gCn5sr2K9qZRDZ5J5gxJBVJFBKuqNtpRIswBxLDk6tkg5xsqZRnMmgFEqIl1kq8RKVERN0sOI3oJoRDSNksRDwXIsV8yhkDk0anuJIKHREAlj0AUuCnnH/koXfyQyegph7I8V4fIY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=E49xcUFr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="E49xcUFr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63AF0C4CEFB; Thu, 4 Dec 2025 20:42:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764880977; bh=L7d1qiM8xYz9QN18vNQm2ZFkGv4gdjDPj0W/v44zrYc=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=E49xcUFrUYpc6YCgzn86tmUuUfbaibTxEmI2IJLx73nGpi4hj3uihtwNwev1fDz5l TYRl5dhm9c4SzPPNeNxeIROryGXc7mO88PPpto7MEwPNkZk5Ap9SIKgqxJXDoymj7m 8f2uX+S1hxDVEEEQ2oYgSYb0jxUIXlhngOGwgPDGJt+rbYOUYnks3dx/Udm/Ta0FjM Y/9qh9nv+mQj78jde6qpu+ICfznOJLcvdfyV0w/+BMvdDWmRjMrh14xk18aU7C7c7B 4n4z1JwpOPmqBaz/9dHKJihqfPNdEzudEm+KutRk9gGT6ZJHcVyzNshg0R1siuvxbT EdT1TyIS3nUFw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 4B616CE0E8C; Thu, 4 Dec 2025 12:42:52 -0800 (PST) Date: Thu, 4 Dec 2025 12:42:52 -0800 From: "Paul E. McKenney" To: Borislav Petkov Cc: iommu@lists.linux.dev, Joerg Roedel , Suravee Suthikulpanit , Will Deacon , Robin Murphy , linux-kernel@vger.kernel.org Subject: Re: amd iommu: rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 8 jiffies s: 113 root: 0x1/. Message-ID: Reply-To: paulmck@kernel.org References: <20251126143219.GBaScPc1b6RAC9ZfCv@fat_crate.local> <20251126152637.GDaSccLZVBEOs20n6T@fat_crate.local> <17147c98-9f0d-45d0-9593-3ede27ba6135@paulmck-laptop> <20251203124422.GBaTAwpmOzChS2MDhX@fat_crate.local> <20251204144505.GCaTGecavu-E56OR8V@fat_crate.local> 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=us-ascii Content-Disposition: inline In-Reply-To: <20251204144505.GCaTGecavu-E56OR8V@fat_crate.local> On Thu, Dec 04, 2025 at 03:45:05PM +0100, Borislav Petkov wrote: > On Wed, Dec 03, 2025 at 09:16:37AM -0800, Paul E. McKenney wrote: > > Or to some value that works for you. But if you are not looking to be > > an expedited RCU CPU stall-warning pioneer, yes, setting it to zero is > > a good approach. > > > > If you would like to be a more sane pioneer, setting it to (say) 11000 > > (or 11 seconds) could be appropriate. But what fun is sanity? ;-) > > Oh, I have a lot of excitement even without RCU experiments. :-P ;-) ;-) ;-) > But if you need me to try things, lemme know. > > For now I've simply reset the values as to what defconfig sets them to: > > CONFIG_RCU_CPU_STALL_TIMEOUT=21 > CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=0 Sounds good, and thank you! Thanx, Paul > Thx. > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette