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 5C6B922FE0E; Mon, 16 Feb 2026 23:26:38 +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=1771284398; cv=none; b=VRDw3KiSXmTIQNUlVyY9pBqp32xCZWz9mG9k4Lfqml2vATzudbB9/NQsnPUP5vKgP1vzqa2c2nl43HdwBCqmOxUGeHJ/qqSVEyomqdDjcE8y25oJIUwtM8ctjAboFQz1GM9hQ2UzqFYKMjTKoWvG9UyXew7yYUNRZ6Gbf0fmc+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771284398; c=relaxed/simple; bh=ssjv9Kr7MZ13eUSS+beOYAfhQx0ZYeS/67c2Lfb9HYk=; h=Date:To:From:Subject:Message-Id; b=ST8O9NOGMW3IZ6nOJ1OgD+13eWtsw2M1jmVixMhCNT1pIoOCUPHz+VsduXBV9QW3sQTjR9sORa43jLfyvdRxh2wiIkDcI0q20h9UryOvOPnIoCiep/WgWF3lInUi0HAyLZFPzZVaschDMiQgkICholsvrF/bSFaOdfGMCJOSeYs= 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=DOGQX9UQ; 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="DOGQX9UQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BBA73C116C6; Mon, 16 Feb 2026 23:26:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1771284397; bh=ssjv9Kr7MZ13eUSS+beOYAfhQx0ZYeS/67c2Lfb9HYk=; h=Date:To:From:Subject:From; b=DOGQX9UQXAN8lvFfWL4/ZNuHYhiOsGRuWg/83eshJRTeU2R4UavDP0oPZtySFllPp LYrDmDMPfTrmZn+tZrR6+hA6gE9Q/U3hQui5t5Bxa5cx2tJ6r5YA/U8VoF3vCX1hS8 K8EzVjG0KX4sjtFFlyKeh/JuibdF7C3U2mht9ryM= Date: Mon, 16 Feb 2026 15:26:37 -0800 To: mm-commits@vger.kernel.org,ziy@nvidia.com,stable@vger.kernel.org,shy828301@gmail.com,ryan.roberts@arm.com,npache@redhat.com,lorenzo.stoakes@oracle.com,liam.howlett@oracle.com,lance.yang@linux.dev,Kartikey406@gmail.com,i@maskray.me,dev.jain@arm.com,david@kernel.org,baolin.wang@linux.alibaba.com,baohua@kernel.org,ackerleytng@google.com,kartikey406@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-thp-deny-thp-for-files-on-anonymous-inodes.patch added to mm-hotfixes-unstable branch Message-Id: <20260216232637.BBA73C116C6@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: thp: deny THP for files on anonymous inodes has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-thp-deny-thp-for-files-on-anonymous-inodes.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-thp-deny-thp-for-files-on-anonymous-inodes.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Deepanshu Kartikey Subject: mm: thp: deny THP for files on anonymous inodes Date: Sat, 14 Feb 2026 05:45:35 +0530 file_thp_enabled() incorrectly allows THP for files on anonymous inodes (e.g. guest_memfd and secretmem). These files are created via alloc_file_pseudo(), which does not call get_write_access() and leaves inode->i_writecount at 0. Combined with S_ISREG(inode->i_mode) being true, they appear as read-only regular files when CONFIG_READ_ONLY_THP_FOR_FS is enabled, making them eligible for THP collapse. Anonymous inodes can never pass the inode_is_open_for_write() check since their i_writecount is never incremented through the normal VFS open path. The right thing to do is to exclude them from THP eligibility altogether, since CONFIG_READ_ONLY_THP_FOR_FS was designed for real filesystem files (e.g. shared libraries), not for pseudo-filesystem inodes. For guest_memfd, this allows khugepaged and MADV_COLLAPSE to create large folios in the page cache via the collapse path, but the guest_memfd fault handler does not support large folios. This triggers WARN_ON_ONCE(folio_test_large(folio)) in kvm_gmem_fault_user_mapping(). For secretmem, collapse_file() tries to copy page contents through the direct map, but secretmem pages are removed from the direct map. This can result in a kernel crash: BUG: unable to handle page fault for address: ffff88810284d000 RIP: 0010:memcpy_orig+0x16/0x130 Call Trace: collapse_file hpage_collapse_scan_file madvise_collapse Secretmem is not affected by the crash on upstream as the memory failure recovery handles the failed copy gracefully, but it still triggers confusing false memory failure reports: Memory failure: 0x106d96f: recovery action for clean unevictable LRU page: Recovered Check IS_ANON_FILE(inode) in file_thp_enabled() to deny THP for all anonymous inode files. Link: https://syzkaller.appspot.com/bug?extid=33a04338019ac7e43a44 Link: https://lore.kernel.org/linux-mm/CAEvNRgHegcz3ro35ixkDw39ES8=U6rs6S7iP0gkR9enr7HoGtA@mail.gmail.com Link: https://lkml.kernel.org/r/20260214001535.435626-1-kartikey406@gmail.com Fixes: 7fbb5e188248 ("mm: remove VM_EXEC requirement for THP eligibility") Signed-off-by: Deepanshu Kartikey Reported-by: syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=33a04338019ac7e43a44 Tested-by: syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com Tested-by: Lance Yang Acked-by: David Hildenbrand (Arm) Reviewed-by: Barry Song Reviewed-by: Ackerley Tng Tested-by: Ackerley Tng Reviewed-by: Lorenzo Stoakes Cc: Baolin Wang Cc: Dev Jain Cc: Fangrui Song Cc: Liam Howlett Cc: Nico Pache Cc: Ryan Roberts Cc: Yang Shi Cc: Zi Yan Cc: Signed-off-by: Andrew Morton --- mm/huge_memory.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/huge_memory.c~mm-thp-deny-thp-for-files-on-anonymous-inodes +++ a/mm/huge_memory.c @@ -94,6 +94,9 @@ static inline bool file_thp_enabled(stru inode = file_inode(vma->vm_file); + if (IS_ANON_FILE(inode)) + return false; + return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode); } _ Patches currently in -mm which might be from kartikey406@gmail.com are mm-thp-deny-thp-for-files-on-anonymous-inodes.patch