On Wed, Mar 31, 2021 at 08:11:38AM +0200, Dmitry Vyukov wrote: > On Wed, Mar 31, 2021 at 12:26 AM syzbot > <syzbot+1a33233ccd8201ec2...@syzkaller.appspotmail.com> wrote: > > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: db24726b Merge tag 'integrity-v5.12-fix' of git://git.kern.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=16c16b7cd00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=daeff30c2474a60f > > dashboard link: https://syzkaller.appspot.com/bug?extid=1a33233ccd8201ec2322 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+1a33233ccd8201ec2...@syzkaller.appspotmail.com > > I think this is a LOCKDEP issue. +LOCKDEP maintainers. > > Another bug happened on another thread ("WARNING: possible circular > locking dependency detected"). Lockdep disabled lock tracking > ("debug_locks = 0" in the report), which probably made it miss > rcu_unlock somewhere, but it did not turn off reporting yet and > produced the false positive first. > > I think if LOCKDEP disables lock tracking, it must also disable > reporting of issues that require lock tracking. That would avoid false > positives.
Still early and brain hasn't really booted yet, but features that require lock tracking are supposed to check debug_locks. And afaict debug_lockdep_rcu_enabled(), which is called by RCU_LOCKDEP_WARN(), which is called by rcu_sleep_check() does just that.
