| Message ID | 20190716000520.230595-1-henryburns@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] mm/z3fold.c: Reinitialize zhdr structs after migration | expand |
On Mon, Jul 15, 2019 at 5:05 PM Henry Burns <henryburns@google.com> wrote: > > 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. > > Fixes: bba4c5f96ce4 ("mm/z3fold.c: support page migration") > Signed-off-by: Henry Burns <henryburns@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> > --- > Changelog since v1: > - Made comments explicityly refer to new_zhdr->buddy. > > mm/z3fold.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/mm/z3fold.c b/mm/z3fold.c > index 42ef9955117c..f4b2283b19a3 100644 > --- a/mm/z3fold.c > +++ b/mm/z3fold.c > @@ -1352,12 +1352,22 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa > z3fold_page_unlock(zhdr); > 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); > -- > 2.22.0.510.g264f2c817a-goog >
diff --git a/mm/z3fold.c b/mm/z3fold.c index 42ef9955117c..f4b2283b19a3 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -1352,12 +1352,22 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa z3fold_page_unlock(zhdr); 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);
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. Fixes: bba4c5f96ce4 ("mm/z3fold.c: support page migration") Signed-off-by: Henry Burns <henryburns@google.com> --- Changelog since v1: - Made comments explicityly refer to new_zhdr->buddy. mm/z3fold.c | 10 ++++++++++ 1 file changed, 10 insertions(+)