From 79789db03fdd77510cfb35cb4b3bd52b6c50c901 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Mon, 12 Jul 2021 16:32:07 +0100 Subject: mm: Make copy_huge_page() always available Rewrite copy_huge_page() and move it into mm/util.c so it's always available. Fixes an exposure of uninitialised memory on configurations with HUGETLB and UFFD enabled and MIGRATION disabled. Fixes: 8cc5fcbb5be8 ("mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY") Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Mike Kravetz Signed-off-by: Linus Torvalds --- mm/util.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'mm/util.c') diff --git a/mm/util.c b/mm/util.c index 99c6cc77de9e..9043d03750a7 100644 --- a/mm/util.c +++ b/mm/util.c @@ -731,6 +731,16 @@ int __page_mapcount(struct page *page) } EXPORT_SYMBOL_GPL(__page_mapcount); +void copy_huge_page(struct page *dst, struct page *src) +{ + unsigned i, nr = compound_nr(src); + + for (i = 0; i < nr; i++) { + cond_resched(); + copy_highpage(nth_page(dst, i), nth_page(src, i)); + } +} + int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; int sysctl_overcommit_ratio __read_mostly = 50; unsigned long sysctl_overcommit_kbytes __read_mostly; -- cgit v1.2.3