On 5/15/20 1:21 AM, Qian Cai wrote:
Lockdep is screwed here in next-20200514 due to "BUG: MAX_LOCKDEP_ENTRIES too
low". One of the traces below pointed to this linux-next commit,
8c8e824d4ef0 watch_queue: Introduce a non-repeating system-unique superblock ID
which was accidentally just showed up in next-20200514 along with,
46896d79c514 watch_queue: Add superblock notifications
I did have here,
CONFIG_SB_NOTIFICATIONS=y
CONFIG_MOUNT_NOTIFICATIONS=y
CONFIG_FSINFO=y
While MAX_LOCKDEP_ENTRIES is 32768, I noticed there is one type of lock had a
lot along,
# grep 'type->s_umount_key’ /proc/lockdep_chains | wc -l
6979
The lock_list table entries are for tracking a lock's forward and
backward dependencies. The lockdep_chains isn't the right lockdep file
to look at. Instead, check the lockdep files for entries with the
maximum BD (backward dependency) + FD (forward dependency). That will
give you a better view of which locks are consuming most of the
lock_list entries. Also take a look at lockdep_stats for an overall view
of how much various table entries are being consumed.
Cheers,
Longman
