| Date | Thu, 5 Jan 2023 10:17:59 +0000 | Subject | [PATCH 01/46] hugetlb: don't set PageUptodate for UFFDIO_CONTINUE | From | James Houghton <> |
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If would be bad if we actually set PageUptodate with UFFDIO_CONTINUE; PageUptodate indicates that the page has been zeroed, and we don't want to give a non-zeroed page to the user.
The reason this change is being made now is because UFFDIO_CONTINUEs on subpages definitely shouldn't set this page flag on the head page.
Signed-off-by: James Houghton <jthoughton@google.com> --- mm/hugetlb.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index b39b74e0591a..b061e31c1fb8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6229,7 +6229,16 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, * preceding stores to the page contents become visible before * the set_pte_at() write. */ - __SetPageUptodate(page); + if (!is_continue) + __SetPageUptodate(page); + else if (!PageUptodate(page)) { + /* + * This should never happen; HugeTLB pages are always Uptodate + * as soon as they are allocated. + */ + ret = -EFAULT; + goto out_release_nounlock; + } /* Add shared, newly allocated pages to the page cache. */ if (vm_shared && !is_continue) { -- 2.39.0.314.g84b9a713c41-goog
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