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imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=B4HtHCRB; spf=pass (imf27.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770716046; a=rsa-sha256; cv=none; b=09ynwijnmJtTo9gtaEorOcPvhZk0goS58mLllSGqOa1wJLg7kYAFlmd3MAgUmcECWY77gd IAeCc4OCkVVkrBGZJM+eivBll2hlhJ99PodopILQkBJn8n/U4Qi3Dn2OeNxfB/H1byOiXd bXX4heMEStAFiuNlyh/YmteYiTTVjEs= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 027ED60123; Tue, 10 Feb 2026 09:34:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E64ACC116C6; Tue, 10 Feb 2026 09:34:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770716045; bh=kHOevYKx92hrqdv2N/RAdoI8D2Phsjefi4Civy+4aa4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=B4HtHCRBLN7Jix6BfISAxclRX1styTbisNLFoESjhE7h67PhgXM6TQMJR4WuafMI8 lUkwsjc86dPizQU3zLGN55KxTC22rTFoM2rqCj1vwLnQECh+r+GcDY7wQPQa9XWz60 T3jvFE3KDvl2Rzz37rN2xK+ZeDBIyMip43Yge9nH9Jr30APRiR67CAiEvomhpr6OkA C6ZJqQLeHsLsV6zMfS3ismOHcFqt1zlAc4yxnfAIh+fpRwVPr6czDrmkDhTGWEe7CF f/YFMhGUfX1MlLiEZZWYv0UfNygbKw9FoL82+KkxGUYAE8Ms3OxemEP2Nf0tlSWg1g 1EL5Yz1ahiykg== Message-ID: Date: Tue, 10 Feb 2026 10:33:57 +0100 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: Deepanshu Kartikey Cc: Ackerley Tng , 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: 8bit X-Stat-Signature: xazx4bqqxgtfctqiihr4hjd4tcrpw9js X-Rspamd-Queue-Id: 6CAE740011 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1770716046-493465 X-HE-Meta: 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 InZpHtzT KQDFJ28LzX7eCNnhsK2JDucRgX3mUL/Za9at87fzRQ1R0Ah/X9Y2vQjIVsC8am2Py4WPdFoB3O9TQr6u7xwv5seXl/b7o5r4KpnZFQC6hYURb46c+M1qcFCDoio+5LwzQ2QiraGsiclC8Xv4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/10/26 02:51, Deepanshu Kartikey wrote: > On Tue, Feb 10, 2026 at 1:43 AM David Hildenbrand (Arm) > wrote: >> > >> The following is a bit nasty as well but should do the trick until we rip >> out the CONFIG_READ_ONLY_THP_FOR_FS stuff. >> >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index 03886d4ccecc..4ac1cb36b861 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -40,6 +40,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include "internal.h" >> @@ -94,6 +95,10 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma) >> >> inode = file_inode(vma->vm_file); >> >> + if (mapping_inaccessible(inode->i_mapping) || >> + secretmem_mapping(inode->i_mapping)) >> + return false; >> + >> return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode); >> } >> >> > > Hi David, > > Agreed, using mapping_inaccessible() for guest_memfd and > secretmem_mapping() for secretmem is much simpler than introducing a > new AS flag. No changes needed outside of file_thp_enabled(). > > I will send a v2 with your suggested diff and test it on syzbot. Let's wait a bit until we are in agreement that this is the right thing to do :) -- Cheers, David