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author | David Hildenbrand <david@redhat.com> | 2022-12-22 21:55:11 +0100 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-24 07:24:35 +0100 |
commit | 8d6a675cd744c1af2688778fba2404fdf9737ddd (patch) | |
tree | 2b7021915b20f8da6c0d5d88d320f5e8a0d0da22 /mm/hugetlb.c | |
parent | 6062c992e912df1eedad52cf64efb3d48e8d35c5 (diff) | |
download | linux-8d6a675cd744c1af2688778fba2404fdf9737ddd.tar.gz |
mm/hugetlb: fix uffd-wp handling for migration entries in hugetlb_change_protection()
commit 44f86392bdd165da7e43d3c772aeb1e128ffd6c8 upstream. We have to update the uffd-wp SWP PTE bit independent of the type of migration entry. Currently, if we're unlucky and we want to install/clear the uffd-wp bit just while we're migrating a read-only mapped hugetlb page, we would miss to set/clear the uffd-wp bit. Further, if we're processing a readable-exclusive migration entry and neither want to set or clear the uffd-wp bit, we could currently end up losing the uffd-wp bit. Note that the same would hold for writable migrating entries, however, having a writable migration entry with the uffd-wp bit set would already mean that something went wrong. Note that the change from !is_readable_migration_entry -> writable_migration_entry is harmless and actually cleaner, as raised by Miaohe Lin and discussed in [1]. [1] https://lkml.kernel.org/r/90dd6a93-4500-e0de-2bf0-bf522c311b0c@huawei.com Link: https://lkml.kernel.org/r/20221222205511.675832-3-david@redhat.com Fixes: 60dfaad65aa9 ("mm/hugetlb: allow uffd wr-protect none ptes") Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/hugetlb.c')
-rw-r--r-- | mm/hugetlb.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index cc766ddd24c7..3fc5a214f0b9 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6627,10 +6627,9 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, } else if (unlikely(is_hugetlb_entry_migration(pte))) { swp_entry_t entry = pte_to_swp_entry(pte); struct page *page = pfn_swap_entry_to_page(entry); + pte_t newpte = pte; - if (!is_readable_migration_entry(entry)) { - pte_t newpte; - + if (is_writable_migration_entry(entry)) { if (PageAnon(page)) entry = make_readable_exclusive_migration_entry( swp_offset(entry)); @@ -6638,13 +6637,15 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, entry = make_readable_migration_entry( swp_offset(entry)); newpte = swp_entry_to_pte(entry); - if (uffd_wp) - newpte = pte_swp_mkuffd_wp(newpte); - else if (uffd_wp_resolve) - newpte = pte_swp_clear_uffd_wp(newpte); - set_huge_pte_at(mm, address, ptep, newpte); pages++; } + + if (uffd_wp) + newpte = pte_swp_mkuffd_wp(newpte); + else if (uffd_wp_resolve) + newpte = pte_swp_clear_uffd_wp(newpte); + if (!pte_same(pte, newpte)) + set_huge_pte_at(mm, address, ptep, newpte); } else if (unlikely(is_pte_marker(pte))) { /* No other markers apply for now. */ WARN_ON_ONCE(!pte_marker_uffd_wp(pte)); |