From: Henry Burns henryburns@google.com
[ Upstream commit c92d2f38563db20c20c8db2f98fa1349290477d5 ]
z3fold_page_migration() calls memcpy(new_zhdr, zhdr, PAGE_SIZE). However, zhdr contains fields that can't be directly coppied over (ex: list_head, a circular linked list). We only need to initialize the linked lists in new_zhdr, as z3fold_isolate_page() already ensures that these lists are empty
Additionally it is possible that zhdr->work has been placed in a workqueue. In this case we shouldn't migrate the page, as zhdr->work references zhdr as opposed to new_zhdr.
Link: http://lkml.kernel.org/r/20190716000520.230595-1-henryburns@google.com Fixes: 1f862989b04ade61d3 ("mm/z3fold.c: support page migration") Signed-off-by: Henry Burns henryburns@google.com Reviewed-by: Shakeel Butt shakeelb@google.com Cc: Vitaly Vul vitaly.vul@sony.com Cc: Vitaly Wool vitalywool@gmail.com Cc: Jonathan Adams jwadams@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- mm/z3fold.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/mm/z3fold.c b/mm/z3fold.c index e1686bf6d689..7e764b0d8c8a 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -1350,12 +1350,22 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa unlock_page(page); return -EBUSY; } + if (work_pending(&zhdr->work)) { + z3fold_page_unlock(zhdr); + return -EAGAIN; + } new_zhdr = page_address(newpage); memcpy(new_zhdr, zhdr, PAGE_SIZE); newpage->private = page->private; page->private = 0; z3fold_page_unlock(zhdr); spin_lock_init(&new_zhdr->page_lock); + INIT_WORK(&new_zhdr->work, compact_page_work); + /* + * z3fold_page_isolate() ensures that new_zhdr->buddy is empty, + * so we only have to reinitialize it. + */ + INIT_LIST_HEAD(&new_zhdr->buddy); new_mapping = page_mapping(page); __ClearPageMovable(page); ClearPagePrivate(page);