| Message ID | 20210712153207.39302-1-willy@infradead.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: Make copy_huge_page() always available | expand |
On 7/12/21 8:32 AM, Matthew Wilcox (Oracle) wrote: > 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) <willy@infradead.org> > --- > include/linux/migrate.h | 5 ----- > include/linux/mm.h | 1 + > mm/migrate.c | 48 ----------------------------------------- > mm/util.c | 10 +++++++++ > 4 files changed, 11 insertions(+), 53 deletions(-) Thanks Matthew, Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
On Mon, Jul 12, 2021 at 10:52 AM Mike Kravetz <mike.kravetz@oracle.com> wrote: > > On 7/12/21 8:32 AM, Matthew Wilcox (Oracle) wrote: > > 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) <willy@infradead.org> Reviewed-By: Mina Almasry <almasrymina@google.com> > > --- > > include/linux/migrate.h | 5 ----- > > include/linux/mm.h | 1 + > > mm/migrate.c | 48 ----------------------------------------- > > mm/util.c | 10 +++++++++ > > 4 files changed, 11 insertions(+), 53 deletions(-) > > Thanks Matthew, > > Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> > -- > Mike Kravetz
On Mon, 12 Jul 2021 16:32:07 +0100 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote: > 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. Wait. Exposing uninitialized memory is serious. Can we please include full info on this flaw and decide whether a -stable backport is justified? If not, why not, etc?
On Tue, Jul 13, 2021 at 07:12:44PM -0700, Andrew Morton wrote: > On Mon, 12 Jul 2021 16:32:07 +0100 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote: > > > 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. > > Wait. Exposing uninitialized memory is serious. Can we please include > full info on this flaw and decide whether a -stable backport is justified? > If not, why not, etc? Well, the code was only merged this merge window, so as long as it goes in in the next few weeks, there's no need to trouble -stable with it.
On Tue, Jul 13, 2021 at 7:21 PM Matthew Wilcox <willy@infradead.org> wrote: > > Well, the code was only merged this merge window, so as long as it goes > in in the next few weeks, there's no need to trouble -stable with it. It already went in on Monday as commit 79789db03fdd. Linus
diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 9b7b7cd3bae9..23dadf7aeba8 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -51,7 +51,6 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page); extern int migrate_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page, int extra_count); -extern void copy_huge_page(struct page *dst, struct page *src); #else static inline void putback_movable_pages(struct list_head *l) {} @@ -77,10 +76,6 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping, { return -ENOSYS; } - -static inline void copy_huge_page(struct page *dst, struct page *src) -{ -} #endif /* CONFIG_MIGRATION */ #ifdef CONFIG_COMPACTION diff --git a/include/linux/mm.h b/include/linux/mm.h index 8f8e9d8a8489..629df6a24527 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -874,6 +874,7 @@ void __put_page(struct page *page); void put_pages_list(struct list_head *pages); void split_page(struct page *page, unsigned int order); +void copy_huge_page(struct page *dst, struct page *src); /* * Compound pages have a destructor function. Provide a diff --git a/mm/migrate.c b/mm/migrate.c index 23cbd9de030b..34a9ad3e0a4f 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -536,54 +536,6 @@ int migrate_huge_page_move_mapping(struct address_space *mapping, return MIGRATEPAGE_SUCCESS; } -/* - * Gigantic pages are so large that we do not guarantee that page++ pointer - * arithmetic will work across the entire page. We need something more - * specialized. - */ -static void __copy_gigantic_page(struct page *dst, struct page *src, - int nr_pages) -{ - int i; - struct page *dst_base = dst; - struct page *src_base = src; - - for (i = 0; i < nr_pages; ) { - cond_resched(); - copy_highpage(dst, src); - - i++; - dst = mem_map_next(dst, dst_base, i); - src = mem_map_next(src, src_base, i); - } -} - -void copy_huge_page(struct page *dst, struct page *src) -{ - int i; - int nr_pages; - - if (PageHuge(src)) { - /* hugetlbfs page */ - struct hstate *h = page_hstate(src); - nr_pages = pages_per_huge_page(h); - - if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) { - __copy_gigantic_page(dst, src, nr_pages); - return; - } - } else { - /* thp page */ - BUG_ON(!PageTransHuge(src)); - nr_pages = thp_nr_pages(src); - } - - for (i = 0; i < nr_pages; i++) { - cond_resched(); - copy_highpage(dst + i, src + i); - } -} - /* * Copy the page to its new location */ 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;
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) <willy@infradead.org> --- include/linux/migrate.h | 5 ----- include/linux/mm.h | 1 + mm/migrate.c | 48 ----------------------------------------- mm/util.c | 10 +++++++++ 4 files changed, 11 insertions(+), 53 deletions(-)