On 18/12/22(Sun) 20:55, Martin Pieuchot wrote: > On 17/12/22(Sat) 14:15, David Hill wrote: > > > > > > On 10/28/22 03:46, Renato Aguiar wrote: > > > Use of bbolt Go library causes 7.2 to freeze. I suspect it is triggering > > > some > > > sort of deadlock in mmap because threads get stuck at vmmaplk. > > > > > > I managed to reproduce it consistently in a laptop with 4 cores > > > (i5-1135G7) > > > using one unit test from bbolt: > > > > > > $ doas pkg_add git go > > > $ git clone https://github.com/etcd-io/bbolt.git > > > $ cd bbolt > > > $ git checkout v1.3.6 > > > $ go test -v -run TestSimulate_10000op_10p > > > > > > The test never ends and this is the 'top' report: > > > > > > PID TID PRI NICE SIZE RES STATE WAIT TIME CPU > > > COMMAND > > > 32181 438138 -18 0 57M 13M idle uvn_fls 0:00 0.00% > > > bbolt.test > > > 32181 331169 10 0 57M 13M sleep/1 nanoslp 0:00 0.00% > > > bbolt.test > > > 32181 497390 10 0 57M 13M idle vmmaplk 0:00 0.00% > > > bbolt.test > > > 32181 380477 14 0 57M 13M idle vmmaplk 0:00 0.00% > > > bbolt.test > > > 32181 336950 14 0 57M 13M idle vmmaplk 0:00 0.00% > > > bbolt.test > > > 32181 491043 14 0 57M 13M idle vmmaplk 0:00 0.00% > > > bbolt.test > > > 32181 347071 2 0 57M 13M idle kqread 0:00 0.00% > > > bbolt.test > > > > > > After this, most commands just hang. For example, running a 'ps | grep > > > foo' in > > > another shell would do it. > > > > > > > I can reproduce this on MP, but not SP. Here is /trace from ddb after using > > the ddb.trigger sysctl. Is there any other information I could pull from > > DDB that may help? > > Thanks for the useful report David! > > The issue seems to be a deadlock between the `vmmaplk' and a particular > `vmobjlock'. uvm_map_clean() calls uvn_flush() which sleeps with the > `vmmaplk' held. > > I'll think a bit about this and try to come up with a fix ASAP.
I'm missing a piece of information. All the threads in your report seem to want a read version of the `vmmaplk' so they should not block. Could you reproduce the hang with a WITNESS kernel and print 'show all locks' in addition to all the informations you've reported?
