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([2405:201:682f:389d:8864:6033:780:138b]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-354b21fb723sm8577308a91.10.2026.02.08.19.36.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Feb 2026 19:36:13 -0800 (PST) From: Deepanshu Kartikey To: akpm@linux-foundation.org, david@kernel.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, ackerleytng@google.com, seanjc@google.com, pbonzini@redhat.com, michael.roth@amd.com, vannapurve@google.com Cc: ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com, Deepanshu Kartikey Subject: [PATCH] mm: thp: Deny THP for guest_memfd and secretmem in file_thp_enabled() Date: Mon, 9 Feb 2026 09:05:58 +0530 Message-ID: <20260209033558.22943-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: q7mk97kej6pbgj8yjc1bg63db81zn75a X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: B72D0100008 X-HE-Tag: 1770608175-596949 X-HE-Meta: U2FsdGVkX18s9XjPGwxrjuGW/fDreg6w0GUYdWnj3NMSecHlCJHVn3kEYq3f4ehRnqpaknhcVqupNbaIpji4Svgh8FRRBk6AP+46WSlGVebW9KhxQuGyZxDKJpUtKihbCU0v4p5TLbULz9SJu6fAA80zsRgFahUGIyZgo622gGh/ZEKWHBOzK++DCfxzeiZdm3e1PV7MbrSS8k9/ufdu5n+tuXrvsljahJupYG++r1K0LJJ2cfANZNTAM2tAN3G37X5G6yDOGgExvLtYfc0pFdC+1fMdFH2MQTsHMLZdZxfDb/+t0ajati7+QpNE1hc5UJps3qfu0pXX1wdHNZXPAmECPyUF+EZfcB89Wz1JwGeVPIB3dLXixx4g93XTqJmxdf6dQcKGlYbD2RsjnxZXoiYKc8VrPnnb+mFCmemFc1X3g3Uee316/PoXTuHKkn4TL1IdE8qHhdt7AUOdVgxAzmfgL4J05fOIDjKojQJrTaN3k8U7uqyIcbaYC9y9ga7cheYLKNv6ompMhSoXjE2Z63Zog/SJxQb00qGeZUszjaW3PLgKy5Dgb2bNjmoGzz9EK4QtjS/omwyMaqvG9ElOqOwMDY+s3bcNDggHsucjtifqM1R6l+nVETkFji/rsg3G8/2EEFFzdRtUf2LOaPftJyqSuapClZ0WRD2mBPDxpxxSacyAf82GX4f55J0GE+BbvV3P1kiJD0i8ynLJwXhixyRr8UpdelowsEeWgEx5+54TfO/X2NFKmBQJ6gpjsfXT63kAqflFOKbes57zhF1roO6NANcGkgdh7wBdg8QZ8FpsUi+hUgL/HI/1VKzjG0QsNSoOjQj8vtHUJtjn5z13/fir81oeb8ZgJ9oESn26JEmCcffhIRq9EwQmAOHt/peA+bim1x6V1eq/SX+9Y9Qw4ZJbT6lMwsLTUm6BwnUMGy3q97bAY8qqdcwaVzgMVknBInw41AD8Sa4gAQ7i0dv Oi7yR4Nc 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 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: file_thp_enabled() incorrectly returns true for guest_memfd and secretmem inodes because they appear as regular read-only files when CONFIG_READ_ONLY_THP_FOR_FS is enabled. This allows khugepaged and MADV_COLLAPSE to create large folios in the page cache, but their fault handlers do not support large folios. Add explicit checks for GUEST_MEMFD_MAGIC and SECRETMEM_MAGIC to reject these filesystems early in file_thp_enabled(). Reported-by: syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=33a04338019ac7e43a44 Tested-by: syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com Signed-off-by: Deepanshu Kartikey --- mm/huge_memory.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 40cf59301c21..4f57c78b57dd 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -93,6 +93,9 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma) return false; inode = file_inode(vma->vm_file); + if (inode->i_sb->s_magic == GUEST_MEMFD_MAGIC || + inode->i_sb->s_magic == SECRETMEM_MAGIC) + return false; return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode); } -- 2.43.0