On Mon, Jun 13, 2022 at 08:48:40AM +0800, Xiubo Li wrote: > > On 6/10/22 11:40 PM, Jeff Layton wrote: > > Willy requested that we change this back to warning on folio->private > > being non-NULl. He's trying to kill off the PG_private flag, and so we'd > > like to catch where it's non-NULL. > > > > Add a VM_WARN_ON_FOLIO (since it doesn't exist yet) and change over to > > using that instead of VM_BUG_ON_FOLIO along with testing the ->private > > pointer. > > > > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > --- > > fs/ceph/addr.c | 2 +- > > include/linux/mmdebug.h | 9 +++++++++ > > 2 files changed, 10 insertions(+), 1 deletion(-) > > > > diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c > > index b43cc01a61db..b24d6bdb91db 100644 > > --- a/fs/ceph/addr.c > > +++ b/fs/ceph/addr.c > > @@ -122,7 +122,7 @@ static bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio) > > * Reference snap context in folio->private. Also set > > * PagePrivate so that we get invalidate_folio callback. > > */ > > - VM_BUG_ON_FOLIO(folio_test_private(folio), folio); > > + VM_WARN_ON_FOLIO(folio->private, folio); > > folio_attach_private(folio, snapc); > > return ceph_fscache_dirty_folio(mapping, folio); I found a couple of places where page->private needs to be NULLed out. Neither of them are Ceph's fault. I decided that testing whether folio->private and PG_private are in agreement was better done in folio_unlock() than in any of the other potential places we could check for it. diff --git a/mm/filemap.c b/mm/filemap.c index 8ef861297ffb..acef71f75e78 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1535,6 +1535,9 @@ void folio_unlock(struct folio *folio) BUILD_BUG_ON(PG_waiters != 7); BUILD_BUG_ON(PG_locked > 7); VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + VM_BUG_ON_FOLIO(!folio_test_private(folio) && + !folio_test_swapbacked(folio) && + folio_get_private(folio), folio); if (clear_bit_unlock_is_negative_byte(PG_locked, folio_flags(folio, 0))) folio_wake_bit(folio, PG_locked); } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 2e2a8b5bc567..af0751a79c19 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2438,6 +2438,7 @@ static void __split_huge_page_tail(struct page *head, int tail, page_tail); page_tail->mapping = head->mapping; page_tail->index = head->index + tail; + page_tail->private = 0; /* Page flags must be visible before we make the page non-compound. */ smp_wmb(); diff --git a/mm/migrate.c b/mm/migrate.c index eb62e026c501..fa8e36e74f0d 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1157,6 +1157,8 @@ static int unmap_and_move(new_page_t get_new_page, newpage = get_new_page(page, private); if (!newpage) return -ENOMEM; + BUG_ON(compound_order(newpage) != compound_order(page)); + newpage->private = 0; rc = __unmap_and_move(page, newpage, force, mode); if (rc == MIGRATEPAGE_SUCCESS)
