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 C1741305688 for ; Thu, 9 Jul 2026 02:06:54 +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=1783562816; cv=none; b=bfFOWkwMPsPPrnJ3AbdaKIDsbiWyvWSYKY1LzXn+qGaMkZvEbwr5+zmGkgrUjPC6aPGm7Kpak7/rLQ6G+5KM3YzA5TxNyLx1ncrH9fHHql9UEcFcpGSeU+bkJfXfggOj2UJSNEbTxt7P+Jf+Vo2yATNViQ9Z5mDQLP76PWVObck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783562816; c=relaxed/simple; bh=ZC7grLdhAoYXv1eM0Y+CqEggMmBlz7U9zuPMogSU2Hc=; h=Date:To:From:Subject:Message-Id; b=L1V1KO/nfGFww80KilSjuDETZMlP7x6P5CXHkyWXtFZiLXnFoMZglc2CItBlvO2WJdy53Ej1UX9N1f7Bsq9Lzc70KDuUPaEzn+LASON9I5hmLhGyStIPdkYGxGiUN4I3AvVSlLjP0MIKSrddBMl3F3a77ddfHlX/Hpr9PgWRoTk= 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=zOgUM3sz; 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="zOgUM3sz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44FD91F000E9; Thu, 9 Jul 2026 02:06:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783562814; bh=CXM3MUzoCynSwY7tXXiK+fPPUv7MrW1QJeJk9AZwBGY=; h=Date:To:From:Subject; b=zOgUM3szjaHU/QbmAtuuV1ZASorNZqoQNMjiMTSsE7FKR/cSrtuMuMdXXCO2ZgSna J7LGoQcIcGfI3P1aCAT2bbJHy5DhtO8sGecG2lMWUGH1HZCAzFTPWAURiKSl2GwaTE H7yzTkFWfEVxSmpnvwEENQS200tQeciA8png+Kd8= Date: Wed, 08 Jul 2026 19:06:53 -0700 To: mm-commits@vger.kernel.org,kas@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-add-vm_uffd_rwp-vma-flag.patch added to mm-new branch Message-Id: <20260709020654.44FD91F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: add VM_UFFD_RWP VMA flag has been added to the -mm mm-new branch. Its filename is mm-add-vm_uffd_rwp-vma-flag.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-add-vm_uffd_rwp-vma-flag.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: "Kiryl Shutsemau (Meta)" Subject: mm: add VM_UFFD_RWP VMA flag Date: Wed, 8 Jul 2026 12:14:06 +0100 Preparatory patch for userfaultfd read-write protection (RWP). RWP extends userfaultfd protection from plain write-protection (WP) to full read-write protection: accesses to an RWP-protected range -- reads as well as writes -- trap through userfaultfd. Reserve VM_UFFD_RWP, add the userfaultfd_rwp() and userfaultfd_protected() helpers, and wire up the smaps "ur" entry and the trace-flag table the rest of the series will use. The flag is gated on CONFIG_USERFAULTFD_RWP, which is introduced together with the UAPI in a later patch; until then VM_UFFD_RWP aliases VM_NONE and every downstream check folds to dead code. Nothing sets or queries the flag yet. Link: https://lore.kernel.org/20260708111417.173443-6-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau Assisted-by: Claude:claude-opus-4-6 Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: SeongJae Park Reviewed-by: Lorenzo Stoakes Cc: Andrea Arcangeli Cc: David Hildenbrand Cc: James Houghton Cc: Jonathan Corbet Cc: Liam Howlett Cc: Paolo Bonzini Cc: Peter Xu Cc: Sean Christopherson Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton --- Documentation/filesystems/proc.rst | 1 fs/proc/task_mmu.c | 3 + include/linux/mm.h | 41 ++++++++++++++++-------- include/linux/userfaultfd_k.h | 45 +++++++++++++++++++++------ include/trace/events/mmflags.h | 7 ++++ 5 files changed, 74 insertions(+), 23 deletions(-) --- a/Documentation/filesystems/proc.rst~mm-add-vm_uffd_rwp-vma-flag +++ a/Documentation/filesystems/proc.rst @@ -608,6 +608,7 @@ encoded manner. The codes are the follow um userfaultfd missing tracking uw userfaultfd wr-protect tracking ui userfaultfd minor fault + ur userfaultfd read-write-protect tracking ss shadow/guarded control stack page sl sealed lf lock on fault pages --- a/fs/proc/task_mmu.c~mm-add-vm_uffd_rwp-vma-flag +++ a/fs/proc/task_mmu.c @@ -1237,6 +1237,9 @@ static void show_smap_vma_flags(struct s #ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR [ilog2(VM_UFFD_MINOR)] = "ui", #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ +#ifdef CONFIG_USERFAULTFD_RWP + [ilog2(VM_UFFD_RWP)] = "ur", +#endif #ifdef CONFIG_ARCH_HAS_USER_SHADOW_STACK [ilog2(VM_SHADOW_STACK)] = "ss", #endif --- a/include/linux/mm.h~mm-add-vm_uffd_rwp-vma-flag +++ a/include/linux/mm.h @@ -354,6 +354,7 @@ enum { #endif DECLARE_VMA_BIT(UFFD_MINOR, 41), DECLARE_VMA_BIT(SEALED, 42), + DECLARE_VMA_BIT(UFFD_RWP, 43), /* Flags that reuse flags above. */ DECLARE_VMA_BIT_ALIAS(PKEY_BIT0, HIGH_ARCH_0), DECLARE_VMA_BIT_ALIAS(PKEY_BIT1, HIGH_ARCH_1), @@ -497,12 +498,17 @@ enum { #else #define VM_UFFD_MINOR VM_NONE #endif +#ifdef CONFIG_USERFAULTFD_RWP +#define VM_UFFD_RWP INIT_VM_FLAG(UFFD_RWP) +#else +#define VM_UFFD_RWP VM_NONE +#endif /* - * vma_flags_t masks for the userfaultfd VMA flags. VMA_UFFD_MINOR is gated on - * the same config as VM_UFFD_MINOR -- which implies 64BIT, where the bit fits - * -- so an out-of-range bit is never fed to mk_vma_flags() on a build whose - * bitmap cannot hold it. + * vma_flags_t masks for the userfaultfd VMA flags. The two high-bit modes are + * gated on the same configs as their VM_* flags above -- both of which imply + * 64BIT -- so an out-of-range bit is never fed to mk_vma_flags() on a build + * whose bitmap cannot hold it. */ #define VMA_UFFD_MISSING mk_vma_flags(VMA_UFFD_MISSING_BIT) #define VMA_UFFD_WP mk_vma_flags(VMA_UFFD_WP_BIT) @@ -511,6 +517,11 @@ enum { #else #define VMA_UFFD_MINOR EMPTY_VMA_FLAGS #endif +#ifdef CONFIG_USERFAULTFD_RWP +#define VMA_UFFD_RWP mk_vma_flags(VMA_UFFD_RWP_BIT) +#else +#define VMA_UFFD_RWP EMPTY_VMA_FLAGS +#endif #ifdef CONFIG_64BIT #define VM_ALLOW_ANY_UNCACHED INIT_VM_FLAG(ALLOW_ANY_UNCACHED) @@ -649,22 +660,24 @@ enum { * reconsistuted upon page fault, so necessitate page table copying upon fork. * * Note that these flags should be compared with the DESTINATION VMA not the - * source, as VM_UFFD_WP may not be propagated to destination, while all other - * flags will be. + * source: VM_UFFD_WP and VM_UFFD_RWP may be cleared on the destination + * (dup_userfaultfd() -> userfaultfd_reset_ctx() when the parent context did + * not negotiate UFFD_FEATURE_EVENT_FORK), while all other flags propagate. * * VM_PFNMAP / VM_MIXEDMAP - These contain kernel-mapped data which cannot be * reasonably reconstructed on page fault. * * VM_UFFD_WP - Encodes metadata about an installed uffd - * write protect handler, which cannot be - * reconstructed on page fault. + * VM_UFFD_RWP write- or read-write-protect handler, which + * cannot be reconstructed on page fault. * - * We always copy pgtables when dst_vma has uffd-wp - * enabled even if it's file-backed - * (e.g. shmem). Because when uffd-wp is enabled, - * pgtable contains uffd-wp protection information, - * that's something we can't retrieve from page cache, - * and skip copying will lose those info. + * We always copy pgtables when dst_vma has the + * uffd PTE bit in use even if it's file-backed + * (e.g. shmem). Because when the uffd bit is + * in use, the pgtable contains the protection + * information, that's something we can't + * retrieve from page cache, and skip copying + * will lose those info. * * VM_MAYBE_GUARD - Could contain page guard region markers which * by design are a property of the page tables --- a/include/linux/userfaultfd_k.h~mm-add-vm_uffd_rwp-vma-flag +++ a/include/linux/userfaultfd_k.h @@ -21,10 +21,11 @@ #include /* The set of all possible UFFD-related VM flags. */ -#define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR) +#define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_MINOR | \ + VM_UFFD_WP | VM_UFFD_RWP) #define __VMA_UFFD_FLAGS mk_vma_flags_from_masks(VMA_UFFD_MISSING, VMA_UFFD_WP, \ - VMA_UFFD_MINOR) + VMA_UFFD_MINOR, VMA_UFFD_RWP) /* * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining @@ -168,7 +169,8 @@ static inline bool is_mergeable_vm_userf /* * Never enable huge pmd sharing on some uffd registered vmas: * - * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry. + * - VM_UFFD_WP and VM_UFFD_RWP VMAs, because the write protect / access + * tracking information is per pgtable entry. * * - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for * VMAs which share huge pmds. (If you have two mappings to the same @@ -179,20 +181,25 @@ static inline bool is_mergeable_vm_userf static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma) { return vma_test_any_mask(vma, - mk_vma_flags_from_masks(VMA_UFFD_WP, VMA_UFFD_MINOR)); + mk_vma_flags_from_masks(VMA_UFFD_WP, VMA_UFFD_RWP, + VMA_UFFD_MINOR)); } /* - * Don't do fault around for either WP or MINOR registered uffd range. For + * Don't do fault around for WP, RWP or MINOR registered uffd range. For * MINOR registered range, fault around will be a total disaster and ptes can * be installed without notifications; for WP it should mostly be fine as long * as the fault around checks for pte_none() before the installation, however - * to be super safe we just forbid it. + * to be super safe we just forbid it; for RWP, pre-faulted neighbours would + * be indistinguishable from accessed pages in PAGEMAP_SCAN (PAGE_IS_ACCESSED) + * and pollute the tracked working set, so each page must be populated by its + * own fault. */ static inline bool uffd_disable_fault_around(struct vm_area_struct *vma) { return vma_test_any_mask(vma, - mk_vma_flags_from_masks(VMA_UFFD_WP, VMA_UFFD_MINOR)); + mk_vma_flags_from_masks(VMA_UFFD_WP, VMA_UFFD_RWP, + VMA_UFFD_MINOR)); } static inline bool userfaultfd_missing(struct vm_area_struct *vma) @@ -210,6 +217,16 @@ static inline bool userfaultfd_minor(str return vma_test_any_mask(vma, VMA_UFFD_MINOR); } +static inline bool userfaultfd_rwp(struct vm_area_struct *vma) +{ + return vma_test_single_mask(vma, VMA_UFFD_RWP); +} + +static inline bool userfaultfd_protected(struct vm_area_struct *vma) +{ + return userfaultfd_wp(vma) || userfaultfd_rwp(vma); +} + static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma, pte_t pte) { @@ -330,6 +347,16 @@ static inline bool userfaultfd_minor(str return false; } +static inline bool userfaultfd_rwp(struct vm_area_struct *vma) +{ + return false; +} + +static inline bool userfaultfd_protected(struct vm_area_struct *vma) +{ + return false; +} + static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma, pte_t pte) { @@ -423,8 +450,8 @@ static inline bool userfaultfd_wp_use_ma } /* - * Returns true if this is a swap pte and was uffd-wp wr-protected in either - * forms (pte marker or a normal swap pte), false otherwise. + * Returns true if this swap pte carries uffd-tracked state in either + * form (pte marker or a normal swap pte), false otherwise. */ static inline bool pte_swp_uffd_any(pte_t pte) { --- a/include/trace/events/mmflags.h~mm-add-vm_uffd_rwp-vma-flag +++ a/include/trace/events/mmflags.h @@ -186,6 +186,12 @@ IF_HAVE_PG_ARCH_3(arch_3) # define IF_HAVE_UFFD_MINOR(flag, name) #endif +#ifdef CONFIG_USERFAULTFD_RWP +# define IF_HAVE_UFFD_RWP(flag, name) {flag, name}, +#else +# define IF_HAVE_UFFD_RWP(flag, name) +#endif + #if defined(CONFIG_64BIT) || defined(CONFIG_PPC32) # define IF_HAVE_VM_DROPPABLE(flag, name) {flag, name}, #else @@ -207,6 +213,7 @@ IF_HAVE_UFFD_MINOR(VM_UFFD_MINOR, "uffd_ {VM_PFNMAP, "pfnmap" }, \ {VM_MAYBE_GUARD, "maybe_guard" }, \ {VM_UFFD_WP, "uffd_wp" }, \ +IF_HAVE_UFFD_RWP(VM_UFFD_RWP, "uffd_rwp" ) \ {VM_LOCKED, "locked" }, \ {VM_IO, "io" }, \ {VM_SEQ_READ, "seqread" }, \ _ Patches currently in -mm which might be from kas@kernel.org are mm-hugetlb-fix-swap-entry-corruption-when-clearing-uffd-wp-at-fork.patch fs-proc-task_mmu-fix-pagemap_scan-written-state-for-unpopulated-ptes.patch mm-decouple-protnone-helpers-from-config_numa_balancing.patch mm-rename-uffd-wp-pte-bit-macros-to-uffd.patch mm-rename-uffd-wp-pte-accessors-to-uffd.patch userfaultfd-test-uffd-vma-flags-through-the-vma_flags_t-api.patch mm-add-vm_uffd_rwp-vma-flag.patch mm-add-mm_cp_uffd_rwp-change_protection-flag.patch mm-preserve-rwp-marker-across-pte-rewrites.patch mm-handle-vm_uffd_rwp-in-khugepaged-rmap-and-gup.patch userfaultfd-add-uffdio_register_mode_rwp-and-uffdio_rwprotect-plumbing.patch mm-userfaultfd-add-rwp-fault-delivery-and-expose-uffdio_register_mode_rwp.patch mm-pagemap-add-page_is_accessed-for-rwp-tracking.patch userfaultfd-add-uffd_feature_rwp_async-for-async-fault-resolution.patch userfaultfd-add-uffdio_set_mode-for-runtime-sync-async-toggle.patch selftests-mm-add-userfaultfd-rwp-tests.patch documentation-userfaultfd-document-rwp-working-set-tracking.patch