From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E22711A6829 for ; Sun, 5 Jul 2026 02:26:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783218386; cv=none; b=GH9MnmlzA9pEzH3O+kVcybRE603koPd3fqPxRbkYOlt59nFWJ45dqEQWjXVrzIorAUPpszoc7rGdwgRjZ5HpvgNNiwBEaDJ/D6Mym16r3j0/V5ma6/qkksXSq5H7Hc85RNnailwzY3TuWypQijRvjur8yb06fsy0SjP+3C/Lc2Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783218386; c=relaxed/simple; bh=pW+sNO3UzO1wkPRbA8HONrMI3wCZK1rPVUT7p1eqAKc=; h=Date:To:From:Subject:Message-Id; b=alJ7olXngCLaEYx5CkJcBTM+MoSv1yJsaaHyIl3KVYjAQ7kGALngOr31POIaG7kMy3Aq5vll/OmxowdQzi7gyMwySpKiKzyEAkTpPtM/oioZvoHbKZm/rAcu6JbOB1tgSR6bx1BA7hV89cGLeUd4dmPZLYGipKXIid7LxHmpKdw= 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=C5uPIgst; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="C5uPIgst" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 714FA1F000E9; Sun, 5 Jul 2026 02:26:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783218384; bh=3elzxcjJwW9czeh1DBh8aDWQlcTgCGJCxxh7qBsxnJA=; h=Date:To:From:Subject; b=C5uPIgstekpcCLK0feRQFBJJS0c+qIsSq0JGNrpcCy8McUeSjAi0Urt80Eh3HPgr/ XpEd9vWxsJ+T/FmAMiIb58J74CGpA0xbjfC/UItoDFw4ILr9WjLiyJfB8w2VFsphWE VMUqmvJ4UnHP8X8i3j3vKbrdwpwUs7FG8uHwU+JI= Date: Sat, 04 Jul 2026 19:26:24 -0700 To: mm-commits@vger.kernel.org,vbabka@kernel.org,surenb@google.com,rppt@kernel.org,mhocko@suse.com,ljs@kernel.org,liam@infradead.org,david@kernel.org,jackmanb@google.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-secretmem-disable-under-highmem.patch added to mm-new branch Message-Id: <20260705022624.714FA1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/secretmem: disable under HIGHMEM has been added to the -mm mm-new branch. Its filename is mm-secretmem-disable-under-highmem.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-secretmem-disable-under-highmem.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next 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: Brendan Jackman Subject: mm/secretmem: disable under HIGHMEM Date: Fri, 03 Jul 2026 14:48:26 +0000 secretmem_fault() allocates a folio with GFP_HIGHUSER and then calls set_direct_map_valid_noflush() without checking folio_test_highmem(). This causes a warning and process crash (vibe-coded reproducer in Link below): Su[ 30.071284] ------------[ cut here ]------------ ccessfully allocated and mapped 2097152000 bytes at 0x3a449000 Populating memor[ 30.074614] CPA: called for zero pte. vaddr = 0 cpa->vaddr = 0 y... [ 30.078636] WARNING: arch/x86/mm/pat/set_memory.c:1840 at __cpa_process_fault+0x34d/0x360, CPU#5: allocate_secret/570 [ 30.084789] CPU: 5 UID: 0 PID: 570 Comm: allocate_secret Not tainted 7.1.0-14063-g4edcdefd4083-dirty #10 PREEMPTLAZY [ 30.090937] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 [ 30.097543] EIP: __cpa_process_fault+0x34d/0x360 [ 30.100514] Code: ff ff 85 c0 0f 89 7d fe ff ff e9 3d fe ff ff 8b 03 8b 00 c7 04 24 c8 ff 64 c1 89 44 24 08 8b 45 e8 89 44 24 04 e8 53 7 a 00 00 <0f> 0b c7 45 f0 f2 ff ff ff e9 fc fc ff ff 90 8d 74 26 00 55 25 00 [ 30.110829] EAX: 00000000 EBX: f64afe98 ECX: 00000000 EDX: 00000000 [ 30.114799] ESI: 00000000 EDI: f64afe98 EBP: f64afe04 ESP: f64afdcc [ 30.118785] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00010246 [ 30.123020] CR0: 80050033 CR2: 46c48ffc CR3: 038c8000 CR4: 00000690 [ 30.127010] Call Trace: [ 30.129078] __change_page_attr_set_clr+0x5e7/0x870 [ 30.132275] ? console_unlock+0x99/0x130 [ 30.135069] ? irq_work_queue+0x36/0x70 [ 30.137853] ? page_address+0xd3/0xf0 [ 30.140421] set_direct_map_invalid_noflush+0x52/0x60 [ 30.143782] secretmem_fault+0x128/0x210 [ 30.146560] __do_fault+0x25/0x90 [ 30.149053] handle_mm_fault+0x6d1/0xcb0 [ 30.151759] exc_page_fault+0x135/0x3b0 [ 30.154487] ? doublefault_shim+0x150/0x150 [ 30.157416] handle_exception+0x130/0x130 [ 30.160137] EIP: 0x804d29f [ 30.162307] Code: 89 54 08 e1 89 54 08 e5 89 54 08 e9 89 54 08 ed c3 0f b6 44 24 08 89 7c 24 0c 69 c0 01 01 01 01 8b 7c 24 04 f7 c7 0f 0 0 00 00 <89> 44 0f fc 75 0e c1 e9 02 f3 ab 8b 44 24 04 8b 7c 24 0c c3 31 d2 [ 30.172936] EAX: 5a5a5a5a EBX: 00000000 ECX: 0c800000 EDX: 3a449000 [ 30.176927] ESI: 00000000 EDI: 3a449000 EBP: bfbbae18 ESP: bfbbadac [ 30.180897] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00010246 [ 30.185161] ? doublefault_shim+0x150/0x150 [ 30.187979] ---[ end trace 0000000000000000 ]--- Bus error (core dumped) ./allocate_secret_i686 2000M The equivalent bug was pointed out by a local Sashiko instance on https://lore.kernel.org/all/20260410151746.61150-3-kalyazin@amazon.com/ This hasn't been reproduced on older kernel versions but from code inspection the bug seems to go back to the original introduction in commit 1507f51255c9f ("mm: introduce memfd_secret system call to create "secret" memory areas"). If this configuration has always been broken, dropping support is not really a regression, so do that. Link: https://github.com/bjackman/limmat-kernel-nix/commit/7b2acba2d3a5ef01400d493a155beb1d135b6bb5 Link: https://lore.kernel.org/20260703-secretmem-highmem-v1-1-30d5ff944664@google.com Fixes: 1507f51255c9f ("mm: introduce memfd_secret system call to create "secret" memory areas") Signed-off-by: Brendan Jackman Reviewed-by: Mike Rapoport (Microsoft) Cc: David Hildenbrand Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/Kconfig~mm-secretmem-disable-under-highmem +++ a/mm/Kconfig @@ -1356,7 +1356,7 @@ config MEMFD_CREATE config SECRETMEM default y bool "Enable memfd_secret() system call" if EXPERT - depends on ARCH_HAS_SET_DIRECT_MAP + depends on ARCH_HAS_SET_DIRECT_MAP && !HIGHMEM help Enable the memfd_secret() system call with the ability to create memory areas visible only in the context of the owning process and _ Patches currently in -mm which might be from jackmanb@google.com are mm-page_alloc-drop-flag-conversion-optimisation.patch mm-secretmem-disable-under-highmem.patch