From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 7DA793CFF4B for ; Tue, 16 Jun 2026 17:48:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781632104; cv=none; b=OTaeO9rimJHN8RxS22Qevrp6kgtfikKo5r9Tpk8uBc4gnEAe7BsgnSzPEndMbBhjcurKU3/DwjAi9qbJEPmMeOVd7rRkfQ7a4vwVnwWqAuIJjv+kCbOiqh7rfi3eLpW3K3QbBhjB7TSs5CTHSrkDeqHejOUunoFuvNnX+pHCQo4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781632104; c=relaxed/simple; bh=03pf5/j3NaGgDKmpev630Mujf0qwm+ljLt88XRCabPg=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: Mime-Version:Content-Type; b=QxSzNMhU/f0KVjRjTBX5Dpr5msaby7hIXStQNRbjNmT1CIbg40CSEFWDW/jDmsUuG3JxuGIltbyS1+4UtXsfvCYAt9Gy+84D3wWO2eSSB+8IIZV61MoHDsbzbxDWlhr43f/3RAwwtDcmw+P+Rb0QBZlSCHSw1x5MPlbnjZmQkXA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=m8JwMayz; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="m8JwMayz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C6431F00A3F; Tue, 16 Jun 2026 17:48:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781632103; bh=03pf5/j3NaGgDKmpev630Mujf0qwm+ljLt88XRCabPg=; h=Date:From:To:Cc:In-Reply-To:References:Subject; b=m8JwMayz7XbS6AU76PPInUfzXGpqSEoOrAZQKKOjS1CYAzO4mePH0twohOKuSg8IW /xtIhZjUdI1BapUeTMFqAhgD+rZ03gUthTY47H7XXF5cYqucEFAGhYt/dAC0KU3KiK oK4kNAdFfU52pdc2KPsQwtPLNutQ+s2xAyXN2LXKUxlVkFuue/01caCmVbPBkrmHNg u+rrztweZuFPxVo/HSAH/hNPe1/qXIdXOx//f9JiGEyvoHCiLxQZ0jC1uBgmLSduS3 MlazOptH8Fu3tWU/h6hZlczWcOxTmccE9HPKwSVkco9txzOrWSCjaIqf1KqJ0D5Idb tZafMN/sFgQqw== Received: from phl-compute-05.internal (phl-compute-05.internal [10.202.2.45]) by mailfauth.phl.internal (Postfix) with ESMTP id 63666F40069; Tue, 16 Jun 2026 13:48:22 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-05.internal (MEProxy); Tue, 16 Jun 2026 13:48:22 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGLmkz7uKr1nHdeJCfWh26WhHA9wRCkSRVB2EW4+YwAPQJy0tDPAsb9w6mSto6Jim TXmhtVARgz9dZ/kbZ+Jy2KdgKFNFpzrhDZL2s4xVNrdL1o9U7eg0H7TU4RXgeKZL7zkTSi 12hL/sUfmr+CQdS/LxNmft5WEYWHX7RZKzbPZU76k0LIXxcKUa2E8Ydg+3zl7w6+8gwX5a FD4BcxHlEj8Ul+sPnmaIFwIOml6bwduMOi5D3Qp6hjmjaaA0YBZ3A5QD8GOSc/zpOV04OB NupRapVJwdbyqeig+p+3mE+TaSOTPzdhaRIGO4n23T3ik2jjdjkQYmCS2D2PZ+XK/DT8nP CnNKswe5fuJKDBXEhnuQICuPAezf1l00yhkHiurqK3KdvXmS8u+IZQ1jF7kjzygfo3BNo+ hIHWpGSlAcPMP/TWBpAtb8bMTwJ+UvjqUOvngcZP7Me0JlG8P2ob2fLnttpgKirkHN235n 4OA84mYLT4ZtuYUeCgC7w1FVnKyJACWws35BuvNoPCdNpqFY4/mHMbd+KJzJzDdSz4zS2d hAFCn8R+kCrRduBGqMEwq4ORLPMVIi0lAGXI0e2AmBwkDVwJYI63yLN+VA4x3GcPKSGucb txZaSlTIxYCn75wMI9nIrRS7105rTtpR1XwgzRTdrQK9VUyVMoWO0tcX0wCg X-ME-Proxy: Feedback-ID: i67ae4b3e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 16 Jun 2026 13:48:21 -0400 (EDT) Date: Tue, 16 Jun 2026 10:48:21 -0700 From: "Dan Williams (nvidia)" To: Dave Jiang , linux-cxl@vger.kernel.org Cc: djbw@kernel.org, dave@stgolabs.net, jic23@kernel.org, alison.schofield@intel.com, vishal.l.verma@intel.com, flavien@nus.edu.sg, stable@vger.kernel.org Message-ID: <6a318c65234a_199fc4100d4@djbw-dev.notmuch> In-Reply-To: <20260616004007.4186004-3-dave.jiang@intel.com> References: <20260616004007.4186004-1-dave.jiang@intel.com> <20260616004007.4186004-3-dave.jiang@intel.com> Subject: Re: [PATCH 2/2] cxl/mce: Serialize the MCE handler against endpoint teardown Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Dave Jiang wrote: > CXL endpoint has a shorter lifetime than CXL memdev state (mds) and > the MCE notifier is part of the mds. The MCE handler needs to take > a reference on the endpoint in order to keep it alive while operating > on it. Take the cxlmd lock to verify the endpoint is still valid and > take a reference on it before accessing it. The only way to synchronize against the removal of cxlmd would be to lock its parent device which is moving in the wrong direction. This lifetime problem disappears with a region-relative mce notification.