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 8EC8C1D5ADE; Thu, 10 Apr 2025 22:47:46 +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=1744325266; cv=none; b=YzxZ5U3ZmsbvVg3VwzU/NJYUQ9plyNhtqCtsphuhv8RNoG94QdnXkH++LwEJaQkDUpBbKqDIPo3Go4kZyygW2lRSzW3xf42v1KMbVdenI2tJbzRck8TN/MBGXasKJgQOR4eJ4vOKW1vFquPUems1cwqXsr5LHko9N41APqc1SAM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744325266; c=relaxed/simple; bh=1tnfPuvkdBHhkMd126G0IxK9k3gsj3KHkqYbgp6rqwk=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=t9VJB7dKsIqJ0fR3u5VO/GgfvMZXiTtgIulRHQBTRfTcBkvvq1B3VBSO1sWk60QvWpneBY3h4QknNWYr9lU0lHrf/rqu6IX7NDuA276YqQjhgrRA/6OENHkz6qYaqBiH0RN+cxlCIPmee0BamBXER1ak9ibAwwVjmn3NdsmOaUU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=e6xef16q; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="e6xef16q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72DF3C4CEDD; Thu, 10 Apr 2025 22:47:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1744325266; bh=1tnfPuvkdBHhkMd126G0IxK9k3gsj3KHkqYbgp6rqwk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=e6xef16qlSCuaWmvesXMrxudpX3PdJoqdNQrXzsVNJrRRrc/hIgkchadNM34Ppb4j YRP22ogIXwogTnAqDkh7D1n1YtKcQftorM0XAqg0S2/V4Yun6qCg+vGECTW9UKKua2 l9Tu9D3P64Os0dK/iz7clScFQuOJTR8wIZOF5Qj8= Date: Thu, 10 Apr 2025 15:47:44 -0700 From: Andrew Morton To: Alexander Gordeev Cc: Andrey Ryabinin , Hugh Dickins , Nicholas Piggin , Guenter Roeck , Juergen Gross , Jeremy Fitzhardinge , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 3/3] mm: Protect kernel pgtables in apply_to_pte_range() Message-Id: <20250410154744.44991b2abe5f842e34320917@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 10 Apr 2025 16:50:33 +0200 Alexander Gordeev wrote: > On Tue, Apr 08, 2025 at 06:07:32PM +0200, Alexander Gordeev wrote: > > Hi Andrew, > > > The lazy MMU mode can only be entered and left under the protection > > of the page table locks for all page tables which may be modified. > > Heiko Carstens noticed that the above claim is not valid, since > v6.15-rc1 commit 691ee97e1a9d ("mm: fix lazy mmu docs and usage"), > which restates it to: > > "In the general case, no lock is guaranteed to be held between entry and exit > of the lazy mode. So the implementation must assume preemption may be enabled" > > That effectively invalidates this patch, so it needs to be dropped. > > Patch 2 still could be fine, except -stable and Fixes tags and it does > not need to aim 6.15-rcX. Do you want me to repost it? I dropped the whole series - let's start again.