DragonFlyBSD

liuyb1 on IRC reported on 2023-06-20 the following HAMMER2 PFS panic.

Reproduce steps:

$ hammer2 snapshot / snap-1
$ hammer2 -u `hammer2 pfs-clid snap-1` pfs-create snap-slave
$ hammer2 -t master -u `hammer2 pfs-clid snap-1` pfs-create snap-master

Kernel panic trace:

panic with 1 spinlocks held
panic: hammer2_chain_insert: collision 0xfffff8011e688a40 0xfffff8011e694580 (key=0000000000000400)
cpuid = 1
Trace beginning at frame 0xfffff80097df6a90
hammer2_chain_insert() at hammer2_chain_insert+0x15b 0xffffffff8096ca7b
hammer2_chain_insert() at hammer2_chain_insert+0x15b 0xffffffff8096ca7b
hammer2_chain_create() at hammer2_chain_create+0xded 0xffffffff809734ed
hammer2_chain_rename() at hammer2_chain_rename+0xd1 0xffffffff809740c1
hammer2_chain_rename_obref() at hammer2_chain_rename_obref+0x20 0xffffffff809741d0
hammer2_chain_indirect_maintenance() at hammer2_chain_indirect_maintenance+0x421 0xffffffff809746b1

Although the above PFS clustering commands are documented in the hammer2(8) man page, the clustering feature is actually still in early development phase, as per the DESIGN doc. So issues are expected and panic is quite possible.

Well, it should report the functionality is not implemented rather than panic the system.