Re: [PATCH v2 7/8] mm/migrate: enable noref migration for jbd2

Jan Kara
2025-04-14T12:12:44Z

On Thu 10-04-25 10:30:28, Davidlohr Bueso wrote:
> On Thu, 10 Apr 2025, Jan Kara wrote:
>
> > > @@ -851,6 +851,8 @@ static int __buffer_migrate_folio(struct address_space *mapping,
> > > bool busy;
> > > bool invalidated = false;
> > >
> > > + VM_WARN_ON_ONCE(test_and_set_bit_lock(BH_Migrate,
> > > + &head->b_state));
> >
> > Careful here. This breaks the logic with !CONFIG_DEBUG_VM.
>
> Ok, I guess just a WARN_ON_ONCE() here then.

Or just:

bool migrating = test_and_set_bit_lock(BH_Migrate, &head->b_state);

VM_WARN_ON_ONCE(migrating);

Frankly, I find statements with side-effects in WARN_ON / BUG_ON statements
rather confusing practice...

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR