From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 F2D513E2756; Mon, 17 Aug 2026 09:42:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786959782; cv=none; b=frbD5x8lCh5FEzSnKalmTvJaDso1Sy9x78qGqNLtHHcd7rp/pFjBGpNXGqzMqKfF1GepYhnKogX26cNeIlV57nQ+tRxMJX3KQVTaqx3VoSktnIzAyv9kxVsOD1ATUeL3wuw6JRWIvlojtY9vgELwIjrL3UQOnLIfWPiNBFNbR8k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786959782; c=relaxed/simple; bh=0BDe1q0/PG+gtr3JikCZCyntPWIP75+wD6CVvwujyaA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=B7KW/xuI3iRONnidFrZ1mkws8/DO7ltyaVnFYFn45NYmCM972bpoEs2d7jJx0qdBKEI7wM6soZi6iFJkZf9nah5wejeNSE4Si8MDGBXpQqylkF4E8O7dJYATkh0YEQ3BEA4FZrCWjjZjvUVI+nMmLXWbXA9XYkX59qRwN8Mkf9o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=R/BcTH4Y; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="R/BcTH4Y" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0BDe1q0/PG+gtr3JikCZCyntPWIP75+wD6CVvwujyaA=; b=R/BcTH4Y4o5+7byWk+ZonuSEuo z7EoSTc+Dkhg1PySdgRQ0aVmIffDMhJZiaNcGIy1n3VIk1s3/80fm5dTY4XtZICnY1GC0HPCDKkeJ F1zJm3IkQEhikj5uHNEQcovf4kkaY45JSalrrXMnuB9wwokoia6UFY7KOmM6vnoBQ6y5VCIObETd7 chxIcyWSekKbMvbo8vLflL+CsIrOWQ7qkveJYKJQy15HNwEyT8/dH0r8SXOIiUFbO45LTXrLPQ1NI ugSQBq24ySnLal8GRO1uPZR+6/z+j134/EkMxGUDon7noaYI//6vWWgRzOHd0hEiJ710KipX7GoAP 6EXtJZIw==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wvtrm-0088JS-27; Mon, 17 Aug 2026 09:42:51 +0000 Date: Mon, 17 Aug 2026 02:42:46 -0700 From: Breno Leitao To: Adam Young Cc: Sudeep Holla , Jassi Brar , Adam Young , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, rmikey@meta.com, kernel-team@meta.com Subject: Re: [PATCH] mailbox: pcc: Free the channel before unmapping the shared memory Message-ID: References: <20260812-pcc-v1-1-5a94d2cc26cc@debian.org> <1a2fb06b-a5e1-46e6-93d8-829b7419142d@amperemail.onmicrosoft.com> 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: <1a2fb06b-a5e1-46e6-93d8-829b7419142d@amperemail.onmicrosoft.com> X-Debian-User: leitao Hello Adam, On Sat, Aug 15, 2026 at 11:58:16PM -0400, Adam Young wrote: > On 8/12/26 08:36, Breno Leitao wrote: > > Free the channel first, before the memory unmap. mbox_free_channel() > > calls pcc_shutdown(), which frees the platform interrupt, and then unmap > > shared memory. > > I posted a related fix undere the MCTP PCC Driver changes. > > This fix is necessary but not sufficient to deal with the race conditions. > Take a look at the series of patches under here: > > https://lore.kernel.org/all/20260721175258.87600-1-admiyo@os.amperecomputing.com/ That looks like a much bigger series, with new features, open discussions, Nacks, and already 45 revisions. This curent fix is only meant to address a real problem (user after free) I am hitting in production systems. My suggestion is that we get this real issue unblocked, even if not complete, while you keep working on your larger series. Thanks, --breno