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