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 924CE338581 for ; Wed, 11 Feb 2026 09:29:47 +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=1770802187; cv=none; b=nPsRt79bWdDmQ7FevKlJVwU1TZ5q7vdTtNLC10me0doQ2RpHYlq2bDCPTp/hjq5KoW+dAWynZAVBec8DltWuQVcpzCmzVjt9vNQ2l8WCffLqZka8wyFblL+9njA4X0KT3px6YBgjqavce7prgQHJRQX6PZdfccNo8nVmhzjy8L8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770802187; c=relaxed/simple; bh=3JiC8/bVFvEvx5XbMpJxOW9AXyw3Kn6clSPJCGhCMfg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QbBH+H4k5Au0nZo4lC9vgIvutUUfkmQeiiX++zS/Xc9qF4dw3YOW0VOuKM/Edo1/UX5KU75Aq/RXe4yLXEcrRhJQve9NaO20T/mUH0U2s3AaS44QvyYhOG32DeRepwvthQE+uhAWlNBKPNhYy+i/fNwc0U5ZXOHAfsonG1nth4Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BMaLRZBS; 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="BMaLRZBS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AF60C4CEF7; Wed, 11 Feb 2026 09:29:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770802187; bh=3JiC8/bVFvEvx5XbMpJxOW9AXyw3Kn6clSPJCGhCMfg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=BMaLRZBSoyJej9h8rFbWett7fI7DOWV01JMoluJ9BEXoEd5AIF4J7k9wct136eI9U zk9Bc6kwY3f0KkRVUwzu5DdBtmEg1chlAnqZYJSHxBQLpnca04PdXtNGANKu8r2eU/ hpcipX0X6sYrojfkh3i3oaPQePjYXTmXnKcNv6BeNI1CfHVQlzq5XOGjZ0IvN3MRjz th9ztcw5lWynGDAHr6IlsolYXGVF1pL78gR7EFWjjynsdV44InfyEoyHSs+XfyLtFt GTEVICd9mm7h0JuFjfLSTrlmtRV/QgpT8oA5si0ejdsnJ5txVNRD/54hrc3NLVJu1L qpWP78YC4CEZQ== Message-ID: <5759bfba-f235-4b2d-bb30-919dcdfe7b2c@kernel.org> Date: Wed, 11 Feb 2026 10:29:40 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: thp: Deny THP for guest_memfd and secretmem in file_thp_enabled() To: Ackerley Tng , Deepanshu Kartikey Cc: akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, seanjc@google.com, pbonzini@redhat.com, michael.roth@amd.com, vannapurve@google.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com References: <20260209033558.22943-1-kartikey406@gmail.com> <0d9cada8-7148-4a5c-a09d-120ef54559d7@kernel.org> <4ed1b111-f2f1-4f89-9308-fdd9d706ca37@kernel.org> <8f188d73-fc97-414b-bdaa-e72032b2bf82@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/11/26 01:58, Ackerley Tng wrote: > Ackerley Tng writes: > >> "David Hildenbrand (Arm)" writes: >> >>> >>> Yes. If there is no guest_memfd we wouldn't need it. >>> >> >> Seems like on 5.15.199 there's a hugepage_vma_check(), which will return >> false since secretmem has vma->vm_ops defined [1], so secretmem VMAs are >> skipped. >> >> [1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/mm/khugepaged.c?h=v5.15.199#n469 >> > > On 6.1.162, secretmem VMAs are skipped since secretmem VMAs are not > anonymous [2]. > > [2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/mm/huge_memory.c?h=v6.1.162#n135 > > Same for 6.6.123 [3]. > > [3] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/mm/huge_memory.c?h=v6.6.123#n125 > > It breaks in 6.12.69 [4]. Do you have a reproducer? If so, which behavior does it trigger? I would assume that we would suddenly have secretmem pages (THP) that have a directmap. Or some page copy would crash the kernel. -- Cheers, David