From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + userfaultfd-wp-support-swap-and-page-migration.patch added to -mm tree Date: Mon, 09 Mar 2020 20:41:46 -0700 Message-ID: <20200310034146.aFOVxxJ1a%akpm@linux-foundation.org> References: <20200305222751.6d781a3f2802d79510941e4e@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:54002 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726195AbgCJDls (ORCPT ); Mon, 9 Mar 2020 23:41:48 -0400 In-Reply-To: <20200305222751.6d781a3f2802d79510941e4e@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: aarcange@redhat.com, bgeffon@google.com, bobbypowers@gmail.com, cracauer@cons.org, david@redhat.com, dgilbert@redhat.com, dplotnikov@virtuozzo.com, gokhale2@llnl.gov, hannes@cmpxchg.org, hughd@google.com, jglisse@redhat.com, kirill@shutemov.name, mcfadden8@llnl.gov, mgorman@suse.de, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, peterx@redhat.com, riel@redhat.com, rppt@linux.vnet.ibm.com, shli@fb.com, xemul@parallels.com, xemul@virtuozzo.com The patch titled Subject: userfaultfd: wp: support swap and page migration has been added to the -mm tree. Its filename is userfaultfd-wp-support-swap-and-page-migration.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-wp-support-swap-and-page-migration.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-wp-support-swap-and-page-migration.patch 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 and is updated there every 3-4 working days ------------------------------------------------------ From: Peter Xu Subject: userfaultfd: wp: support swap and page migration For either swap and page migration, we all use the bit 2 of the entry to identify whether this entry is uffd write-protected. It plays a similar role as the existing soft dirty bit in swap entries but only for keeping the uffd-wp tracking for a specific PTE/PMD. Something special here is that when we want to recover the uffd-wp bit from a swap/migration entry to the PTE bit we'll also need to take care of the _PAGE_RW bit and make sure it's cleared, otherwise even with the _PAGE_UFFD_WP bit we can't trap it at all. In change_pte_range() we do nothing for uffd if the PTE is a swap entry. That can lead to data mismatch if the page that we are going to write protect is swapped out when sending the UFFDIO_WRITEPROTECT. This patch also applies/removes the uffd-wp bit even for the swap entries. Link: http://lkml.kernel.org/r/20200220163112.11409-11-peterx@redhat.com Signed-off-by: Peter Xu Cc: Andrea Arcangeli Cc: Bobby Powers Cc: Brian Geffon Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Cc: Pavel Emelyanov Cc: Rik van Riel Cc: Shaohua Li Signed-off-by: Andrew Morton --- include/linux/swapops.h | 2 ++ mm/huge_memory.c | 3 +++ mm/memory.c | 8 ++++++++ mm/migrate.c | 6 ++++++ mm/mprotect.c | 28 +++++++++++++++++----------- mm/rmap.c | 6 ++++++ 6 files changed, 42 insertions(+), 11 deletions(-) --- a/include/linux/swapops.h~userfaultfd-wp-support-swap-and-page-migration +++ a/include/linux/swapops.h @@ -68,6 +68,8 @@ static inline swp_entry_t pte_to_swp_ent if (pte_swp_soft_dirty(pte)) pte = pte_swp_clear_soft_dirty(pte); + if (pte_swp_uffd_wp(pte)) + pte = pte_swp_clear_uffd_wp(pte); arch_entry = __pte_to_swp_entry(pte); return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); } --- a/mm/huge_memory.c~userfaultfd-wp-support-swap-and-page-migration +++ a/mm/huge_memory.c @@ -2271,6 +2271,7 @@ static void __split_huge_pmd_locked(stru write = is_write_migration_entry(entry); young = false; soft_dirty = pmd_swp_soft_dirty(old_pmd); + uffd_wp = pmd_swp_uffd_wp(old_pmd); } else { page = pmd_page(old_pmd); if (pmd_dirty(old_pmd)) @@ -2303,6 +2304,8 @@ static void __split_huge_pmd_locked(stru entry = swp_entry_to_pte(swp_entry); if (soft_dirty) entry = pte_swp_mksoft_dirty(entry); + if (uffd_wp) + entry = pte_swp_mkuffd_wp(entry); } else { entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); entry = maybe_mkwrite(entry, vma); --- a/mm/memory.c~userfaultfd-wp-support-swap-and-page-migration +++ a/mm/memory.c @@ -733,6 +733,8 @@ copy_one_pte(struct mm_struct *dst_mm, s pte = swp_entry_to_pte(entry); if (pte_swp_soft_dirty(*src_pte)) pte = pte_swp_mksoft_dirty(pte); + if (pte_swp_uffd_wp(*src_pte)) + pte = pte_swp_mkuffd_wp(pte); set_pte_at(src_mm, addr, src_pte, pte); } } else if (is_device_private_entry(entry)) { @@ -762,6 +764,8 @@ copy_one_pte(struct mm_struct *dst_mm, s is_cow_mapping(vm_flags)) { make_device_private_entry_read(&entry); pte = swp_entry_to_pte(entry); + if (pte_swp_uffd_wp(*src_pte)) + pte = pte_swp_mkuffd_wp(pte); set_pte_at(src_mm, addr, src_pte, pte); } } @@ -3098,6 +3102,10 @@ vm_fault_t do_swap_page(struct vm_fault flush_icache_page(vma, page); if (pte_swp_soft_dirty(vmf->orig_pte)) pte = pte_mksoft_dirty(pte); + if (pte_swp_uffd_wp(vmf->orig_pte)) { + pte = pte_mkuffd_wp(pte); + pte = pte_wrprotect(pte); + } set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte); vmf->orig_pte = pte; --- a/mm/migrate.c~userfaultfd-wp-support-swap-and-page-migration +++ a/mm/migrate.c @@ -243,11 +243,15 @@ static bool remove_migration_pte(struct entry = pte_to_swp_entry(*pvmw.pte); if (is_write_migration_entry(entry)) pte = maybe_mkwrite(pte, vma); + else if (pte_swp_uffd_wp(*pvmw.pte)) + pte = pte_mkuffd_wp(pte); if (unlikely(is_zone_device_page(new))) { if (is_device_private_page(new)) { entry = make_device_private_entry(new, pte_write(pte)); pte = swp_entry_to_pte(entry); + if (pte_swp_uffd_wp(*pvmw.pte)) + pte = pte_mkuffd_wp(pte); } } @@ -2334,6 +2338,8 @@ again: swp_pte = swp_entry_to_pte(entry); if (pte_soft_dirty(pte)) swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pte)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); set_pte_at(mm, addr, ptep, swp_pte); /* --- a/mm/mprotect.c~userfaultfd-wp-support-swap-and-page-migration +++ a/mm/mprotect.c @@ -139,11 +139,11 @@ static unsigned long change_pte_range(st } ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); pages++; - } else if (IS_ENABLED(CONFIG_MIGRATION)) { + } else if (is_swap_pte(oldpte)) { swp_entry_t entry = pte_to_swp_entry(oldpte); + pte_t newpte; if (is_write_migration_entry(entry)) { - pte_t newpte; /* * A protection check is difficult so * just be safe and disable write @@ -152,22 +152,28 @@ static unsigned long change_pte_range(st newpte = swp_entry_to_pte(entry); if (pte_swp_soft_dirty(oldpte)) newpte = pte_swp_mksoft_dirty(newpte); - set_pte_at(vma->vm_mm, addr, pte, newpte); - - pages++; - } - - if (is_write_device_private_entry(entry)) { - pte_t newpte; - + if (pte_swp_uffd_wp(oldpte)) + newpte = pte_swp_mkuffd_wp(newpte); + } else if (is_write_device_private_entry(entry)) { /* * We do not preserve soft-dirtiness. See * copy_one_pte() for explanation. */ make_device_private_entry_read(&entry); newpte = swp_entry_to_pte(entry); - set_pte_at(vma->vm_mm, addr, pte, newpte); + if (pte_swp_uffd_wp(oldpte)) + newpte = pte_swp_mkuffd_wp(newpte); + } else { + newpte = oldpte; + } + if (uffd_wp) + newpte = pte_swp_mkuffd_wp(newpte); + else if (uffd_wp_resolve) + newpte = pte_swp_clear_uffd_wp(newpte); + + if (!pte_same(oldpte, newpte)) { + set_pte_at(vma->vm_mm, addr, pte, newpte); pages++; } } --- a/mm/rmap.c~userfaultfd-wp-support-swap-and-page-migration +++ a/mm/rmap.c @@ -1502,6 +1502,8 @@ static bool try_to_unmap_one(struct page swp_pte = swp_entry_to_pte(entry); if (pte_soft_dirty(pteval)) swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pteval)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte); /* * No need to invalidate here it will synchronize on @@ -1601,6 +1603,8 @@ static bool try_to_unmap_one(struct page swp_pte = swp_entry_to_pte(entry); if (pte_soft_dirty(pteval)) swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pteval)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); set_pte_at(mm, address, pvmw.pte, swp_pte); /* * No need to invalidate here it will synchronize on @@ -1667,6 +1671,8 @@ static bool try_to_unmap_one(struct page swp_pte = swp_entry_to_pte(entry); if (pte_soft_dirty(pteval)) swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pteval)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); set_pte_at(mm, address, pvmw.pte, swp_pte); /* Invalidate as we cleared the pte */ mmu_notifier_invalidate_range(mm, address, _ Patches currently in -mm which might be from peterx@redhat.com are mm-gup-rename-nonblocking-to-locked-where-proper.patch mm-gup-fix-__get_user_pages-on-fault-retry-of-hugetlb.patch mm-introduce-fault_signal_pending.patch x86-mm-use-helper-fault_signal_pending.patch arc-mm-use-helper-fault_signal_pending.patch arm64-mm-use-helper-fault_signal_pending.patch powerpc-mm-use-helper-fault_signal_pending.patch sh-mm-use-helper-fault_signal_pending.patch mm-return-faster-for-non-fatal-signals-in-user-mode-faults.patch userfaultfd-dont-retake-mmap_sem-to-emulate-nopage.patch mm-introduce-fault_flag_default.patch mm-introduce-fault_flag_interruptible.patch mm-allow-vm_fault_retry-for-multiple-times.patch mm-gup-allow-vm_fault_retry-for-multiple-times.patch mm-gup-allow-to-react-to-fatal-signals.patch mm-userfaultfd-honor-fault_flag_killable-in-fault-path.patch mm-merge-parameters-for-change_protection.patch userfaultfd-wp-apply-_page_uffd_wp-bit.patch userfaultfd-wp-drop-_page_uffd_wp-properly-when-fork.patch userfaultfd-wp-add-pmd_swp_uffd_wp-helpers.patch userfaultfd-wp-support-swap-and-page-migration.patch khugepaged-skip-collapse-if-uffd-wp-detected.patch userfaultfd-wp-dont-wake-up-when-doing-write-protect.patch userfaultfd-wp-declare-_uffdio_writeprotect-conditionally.patch userfaultfd-selftests-refactor-statistics.patch userfaultfd-selftests-add-write-protect-test.patch