On Tue, Feb 22, 2022 at 09:27:23AM +0100, Jan Kara wrote: > On Thu 17-02-22 20:10:03, Byungchul Park wrote: > > [ 7.009608] =================================================== > > [ 7.009613] DEPT: Circular dependency has been detected. > > [ 7.009614] 5.17.0-rc1-00014-g8a599299c0cb-dirty #30 Tainted: G W > > [ 7.009616] --------------------------------------------------- > > [ 7.009617] summary > > [ 7.009618] --------------------------------------------------- > > [ 7.009618] *** DEADLOCK *** > > [ 7.009618] > > [ 7.009619] context A > > [ 7.009619] [S] (unknown)(&(bit_wait_table + i)->dmap:0) > > [ 7.009621] [W] down_write(&ei->i_data_sem:0) > > [ 7.009623] [E] event(&(bit_wait_table + i)->dmap:0) > > [ 7.009624] > > [ 7.009625] context B > > [ 7.009625] [S] down_read(&ei->i_data_sem:0) > > [ 7.009626] [W] wait(&(bit_wait_table + i)->dmap:0) > > [ 7.009627] [E] up_read(&ei->i_data_sem:0) > > [ 7.009628] > > Looking into this I have noticed that Dept here tracks bitlocks (buffer > locks in particular) but it apparently treats locks on all buffers as one > locking class so it conflates lock on superblock buffer with a lock on > extent tree block buffer. These are wastly different locks with different > locking constraints. So to avoid false positives in filesystems we will > need to add annotations to differentiate locks on different buffers (based > on what the block is used for). Similarly how we e.g. annotate i_rwsem for > different inodes. Hi Jan Kara, I just understood why some guys in this space got mad at Dept reports. I barely got reports from the lock you mentioned with my system - precisely speaking only one, even though I've been rebooting my system many times. But another report that someone gave for me showed there were a lot of reports from the lock. Your comment and the report are so much helpful. I need to assign each's own class first for the buffer locks. Thank you very much. Thanks, Byungchul > > Honza > -- > Jan Kara <jack@xxxxxxxx> > SUSE Labs, CR
