v4.13 shows the same search_free stack as 4.14, but doesn't appear to be fatal (it doesn't result in a hung process nor a block device that cannot be wiped.
I suspect we've got a new upstream issue since 4.20 didn't fix things. Re-running 4.20 to see if we had a stack trace, we don't NULL pointer oops, but there is a stuck worker queue: [ 242.887966] kworker/0:47 D 0 2165 2 0x80000000 [ 242.888014] Workqueue: events cache_set_flush [bcache] [ 242.888027] Call Trace: [ 242.888084] __schedule+0x2a2/0x880 [ 242.888097] ? __switch_to+0xfc/0x4f0 [ 242.888105] schedule+0x2c/0x80 [ 242.888113] schedule_timeout+0x246/0x350 [ 242.888122] wait_for_completion+0xb7/0x140 [ 242.888141] ? wake_up_q+0x80/0x80 [ 242.888151] kthread_stop+0x49/0x110 [ 242.888176] cache_set_flush+0xdb/0x190 [bcache] [ 242.888186] process_one_work+0x20f/0x410 [ 242.888194] worker_thread+0x34/0x400 [ 242.888202] kthread+0x120/0x140 [ 242.888209] ? process_one_work+0x410/0x410 [ 242.888216] ? kthread_park+0x90/0x90 [ 242.888236] ret_from_fork+0x35/0x40 [ 242.888435] INFO: task bcache_allocato:9015 blocked for more than 120 seconds. [ 242.893786] Not tainted 4.20.0-042000rc3-generic #201811182231 [ 242.896669] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 242.900428] bcache_allocato D 0 9015 2 0x80000000 [ 242.900434] Call Trace: [ 242.900448] __schedule+0x2a2/0x880 [ 242.900455] ? __schedule+0x2aa/0x880 [ 242.900462] schedule+0x2c/0x80 [ 242.900480] bch_bucket_alloc+0x19d/0x380 [bcache] [ 242.900503] ? wait_woken+0x80/0x80 [ 242.900519] bch_prio_write+0x190/0x340 [bcache] [ 242.900530] bch_allocator_thread+0x482/0xd10 [bcache] [ 242.900535] kthread+0x120/0x140 [ 242.900546] ? bch_invalidate_one_bucket+0x80/0x80 [bcache] [ 242.900549] ? kthread_park+0x90/0x90 [ 242.900554] ret_from_fork+0x35/0x40 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1784665 Title: mkfs.ext4 over /dev/bcache0 hangs To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1784665/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
