From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 373D27319F for ; Tue, 6 Feb 2024 03:29:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707190176; cv=none; b=HVBeQwGlVFfrdJFXR69ynkwjCtSM9g7rOhut5WpQTj4j2LcaB2AU/GyJsu32Y0HNnDV/poD8svouxrvqI8DMh3f6/X1IOCsV6wJ8V/5nFh/a/6KNAh6591EiBw6cCRBygK7XIf6lrMrrMngeOqY7t4dWk2+txwhAxTjXJ2biYsY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707190176; c=relaxed/simple; bh=K47t6Qn8VX9LZd2vOHxHLV0Ys/CaGLr5+PC1CzGP2TU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=tCEHbEVQthxdgQR9x9qQTOEBv7gfai2XCiW/V6n2jjcG87WXDdtAKCcHXfhCe6xac3wDyMepnmaGN8Ej/qoQzfs+3IxshNvF4gV0MrWr34iY5OZ4O9sTd7yHHQiV4oLWB5p87LPPKkCq4pFI8ahKo8BcpIonBniPCoSxAZWL5N4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=TOoi/NnZ; arc=none smtp.client-ip=209.85.219.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="TOoi/NnZ" Received: by mail-yb1-f202.google.com with SMTP id 3f1490d57ef6-dbf216080f5so8480598276.1 for ; Mon, 05 Feb 2024 19:29:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1707190174; x=1707794974; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=/Tfd5OhfoKoOciQEBeRQDfj0WyGPDWpvLlZKvDtbwOk=; b=TOoi/NnZH+pUj3KWcAJqUOwBc0c7UoEkwSEdwf66eoWBdZcAhhPN8swGlvwOqxFDkp mzzYCAoip5P/yGQwTlxmz9KRuhSX2trcjL6e4e4f9gPhg44AKcksyuKB6YDPrkQ1k5v7 hOtGz9Q0VcgWLJRJj+7SMghr9zd1nI3r0BCfx/DCHMVaYsCbx2TnwZTDtK6kGv/UpUSJ 0chnSZ2EaLKri/8e7zGssw0b7/mLd7kqrAF4j2WtYUEaYr1sp8oLs79qbzDtlrlvdfML wXsoENVlptkI5EG6ELh4enZ5KSfX6Z4m/f/89PSHdVcbKk0Ar2OTfA+eIIOteJf5/swi DEVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707190174; x=1707794974; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=/Tfd5OhfoKoOciQEBeRQDfj0WyGPDWpvLlZKvDtbwOk=; b=i8en16wF9VTQ/JSVlPku0NABdySPwtZxXZ8iXADpV5G/6H8QxpLD+YMlDPui6MKD4v eX47nsymDo++kvdHcgUEpSgJy6swt4Qw1vxFrOjMRGotw3YFzsy+BKBSqrIQJCG95dQl JuwtjM0tJskbdYEo2fU2IXxwaSgyObbizsu8frXhslDoJiB8++L3Jij3iYqk3yURoQe2 verRdSAuAewB2Cwv56tqTOssZd49mIOpNkjsN9AZhXUUUaDvreDJRWk3bQA6c/erMtPn zS2Tm8vdTa0kzxg9Trl85rDxI/t5cHTjfMESkxzt4T/E7SJfL6HtI5aiyPylSMSXNEiG dggg== X-Gm-Message-State: AOJu0Yz6rUcDOz4DxHgL9CEqQ19/d2JWC4FN/htr7lC0kUdOICrvkRJy K5p0YMmVf+o469y+pgXichWTwkUzH608NBh6NvuQk4Hvf+tSw1YXg+lsnbHKMHS9zgH5XN+a0AU 86w== X-Google-Smtp-Source: AGHT+IFGKs7rwk/xOH6e9m0tOkG5KkbLAalcPqOVjHui+Z6DsE6kZ01uHKZEANcR0800iNMQT8Is5W6Gv14= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:160d:b0:dc2:1f34:fac4 with SMTP id bw13-20020a056902160d00b00dc21f34fac4mr139109ybb.2.1707190174210; Mon, 05 Feb 2024 19:29:34 -0800 (PST) Date: Mon, 5 Feb 2024 19:29:32 -0800 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20230911021637.1941096-1-stevensd@google.com> Message-ID: Subject: Re: [PATCH v9 0/6] KVM: allow mapping non-refcounted pages From: Sean Christopherson To: Christoph Hellwig Cc: David Stevens , Yu Zhang , Isaku Yamahata , Zhi Wang , kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Sun, Oct 01, 2023, Christoph Hellwig wrote: > On Fri, Sep 29, 2023 at 09:06:34AM -0700, Sean Christopherson wrote: > > With the cleanups done, playing nice with non-refcounted paged instead of outright > > rejecting them is a wash in terms of lines of code, complexity, and ongoing > > maintenance cost. > > I tend to strongly disagree with that, though. We can't just let these > non-refcounted pages spread everywhere and instead need to fix their > usage. Sorry for the horrifically slow reply. Is there a middle ground somewhere between allowing this willy nilly, and tainting the kernel? I too would love to get the TTM stuff fixed up, but every time I look at that code I am less and less confident that it will happen anytime soon. It's not even clear to me what all code needs to be touched. In other words, is there a way we can unblock David and friends, while still providing a forcing function of some kind to motivate/heckle the TTM (or whatever is making the allocations) to change?