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author | 2020-04-06 20:06:01 -0700 | |
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committer | 2020-04-07 10:43:39 -0700 | |
commit | f45ec5ff16a75f96dac8c89862d75f1d8739efd4 (patch) | |
tree | d43c37d2984d54babd514edfcaa04e6485571a68 /mm | |
parent | userfaultfd: wp: add pmd_swp_*uffd_wp() helpers (diff) | |
download | linux-f45ec5ff16a7.tar.gz linux-f45ec5ff16a7.tar.bz2 linux-f45ec5ff16a7.zip |
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.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-11-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/huge_memory.c | 3 | ||||
-rw-r--r-- | mm/memory.c | 8 | ||||
-rw-r--r-- | mm/migrate.c | 6 | ||||
-rw-r--r-- | mm/mprotect.c | 28 | ||||
-rw-r--r-- | mm/rmap.c | 6 |
5 files changed, 40 insertions, 11 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8164787cd51f..6ecd1045113b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2297,6 +2297,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 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)) @@ -2329,6 +2330,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 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); diff --git a/mm/memory.c b/mm/memory.c index f8b1969669b7..8ac9af73e9d2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -733,6 +733,8 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 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, struct mm_struct *src_mm, 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 *vmf) 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; diff --git a/mm/migrate.c b/mm/migrate.c index c1412e04975e..7160c1556f79 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -243,11 +243,15 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, 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); } } @@ -2338,6 +2342,8 @@ 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); /* diff --git a/mm/mprotect.c b/mm/mprotect.c index e4fa41a24bec..1d823b050329 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -139,11 +139,11 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, } 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(struct vm_area_struct *vma, pmd_t *pmd, 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++; } } diff --git a/mm/rmap.c b/mm/rmap.c index 374a9bfdbffa..ed8889bf4ede 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1502,6 +1502,8 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, 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 *page, struct vm_area_struct *vma, 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 *page, struct vm_area_struct *vma, 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, |