The patch titled
Subject: mm: hugetlb: fix missing cache flush in hugetlb_mcopy_atomic_pte()
has been added to the -mm tree. Its filename is
mm-hugetlb-fix-missing-cache-flush-in-hugetlb_mcopy_atomic_pte.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-fix-missing-cache-flush-in-hugetlb_mcopy_atomic_pte.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-fix-missing-cache-flush-in-hugetlb_mcopy_atomic_pte.patch
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------------------------------------------------------
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: mm: hugetlb: fix missing cache flush in hugetlb_mcopy_atomic_pte()
folio_copy() will copy the data from one page to the target page, then the
target page will be mapped to the user space address, which might have an
alias issue with the kernel address used to copy the data from the page
to. There are 2 ways to fix this issue.
1) insert flush_dcache_page() after folio_copy().
2) replace folio_copy() with copy_user_huge_page() which already
considers the cache maintenance.
We chose 2) way to fix the issue since architectures can optimize this
situation. It is also make backports easier.
Link: https://lkml.kernel.org/r/20220210123058.79206-5-songmuchun@xxxxxxxxxxxxx
Fixes: 8cc5fcbb5be8 ("mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY")
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Fam Zheng <fam.zheng@xxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lars Persson <lars.persson@xxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/hugetlb.c~mm-hugetlb-fix-missing-cache-flush-in-hugetlb_mcopy_atomic_pte
+++ a/mm/hugetlb.c
@@ -5816,7 +5816,8 @@ int hugetlb_mcopy_atomic_pte(struct mm_s
*pagep = NULL;
goto out;
}
- folio_copy(page_folio(page), page_folio(*pagep));
+ copy_user_huge_page(page, *pagep, dst_addr, dst_vma,
+ pages_per_huge_page(h));
put_page(*pagep);
*pagep = NULL;
}
_
Patches currently in -mm which might be from songmuchun@xxxxxxxxxxxxx are
mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd.patch
mm-fix-missing-cache-flush-for-all-tail-pages-of-compound-page.patch
mm-hugetlb-fix-missing-cache-flush-in-copy_huge_page_from_user.patch
mm-hugetlb-fix-missing-cache-flush-in-hugetlb_mcopy_atomic_pte.patch
mm-shmem-fix-missing-cache-flush-in-shmem_mfill_atomic_pte.patch
mm-userfaultfd-fix-missing-cache-flush-in-mcopy_atomic_pte-and-__mcopy_atomic.patch
mm-replace-multiple-dcache-flush-with-flush_dcache_folio.patch
mm-hugetlb-free-the-2nd-vmemmap-page-associated-with-each-hugetlb-page.patch
mm-hugetlb-replace-hugetlb_free_vmemmap_enabled-with-a-static_key.patch
mm-sparsemem-use-page-table-lock-to-protect-kernel-pmd-operations.patch
selftests-vm-add-a-hugetlb-test-case.patch
mm-sparsemem-move-vmemmap-related-to-hugetlb-to-config_hugetlb_page_free_vmemmap.patch
