On 11/07/22(Mon) 07:50, Theo Buehler wrote:
> On Fri, Jun 03, 2022 at 03:02:36PM +0200, Theo Buehler wrote:
> > > Please do note that this change can introduce/expose other issues.
> > 
> > It seems that this diff causes occasional hangs when building snapshots
> > on my mac M1 mini. This happened twice in 10 builds, both times in
> > xenocara. Unfortunately, both times the machine became entirely
> > unresponsive and as I don't have serial console, that's all the info I
> > have...
> > 
> > This machine has been very reliable and built >50 snaps without any hang
> > over the last 2.5 months. I'm now trying snap builds in a loop without
> > the diff to make sure the machine doesn't hang due to another recent
> > kernel change.
> > 
> 
> A little bit of info on this. The first three lines were a bit garbled on
> the screen:
> 
> panic: kernel diagnostic assertion "uvn->_oppa jai c:              ke r  el   
> d iag no   tic a  s   rt n "   map   ==    UL L  | | rw wr                    
>  k
> ite held(amap->amap_lock)" failed: file "/ss/uvm/uvm_fault.c", line 846.
> ernel diagnostic assertion "!_kernel_lock_held
> Stopped at panic+0160:  cmp w21, #0x0  ailed: file "/sys/kern/
>     TID    PID     UID     PRFLAGS     PFLAGS   CPU  COMMAND
>  411910  44540      21    0x100001          0     3  make
> *436444  84241      21    0x100003          0     6  sh
>  227952  53498      21    0x100003          0     5  sh
>  258925  15765      21    0x101005          0     0  make
>  128459   9649      21    0x100003          0     1  tradcpp
>  287213  64216      21    0x100003        0x8     7  make
>  173587   4617    1000    0x100000          0     2  tmux
>  126511  69919       0     0x14000      0x200     4  softnet
> db_enter() at panic+0x15c
> panic() at __assert+0x24
> uvm_fault() at uvm_fault_upper_lookup+0x258
> uvm_fault_upper() at uvm_fault+0xec
> uvm_fault() at udata_abort+0x128
> udata_abort() at do_el0_sync+0xdc
> do_el0_sync() at handle_el0_sync+0x74
> https://www.openbsd.org/ddb.html describes the minimum info required in bug
> reports.  Insufficient info makes it difficult to find and fix bugs.
> ddb{6}> show panic
> *cpu0: kernel diagnostic assertion "uvn->u_obj.uo_refs == 0" failed: file  
> "/sys/kern/uvn_vnode.c", line 231.
>  cpu6: kernel diagnostic assertion "amap == NULL || 
> rw_write_held(amap->am_lock)" failed: file  "/sys/uvm/uvm_fault", line 846.
>  cpu3: kernel diagnostic assertion "!_kernel_lock_held()" failed: file 
> "/sys/kern/kern_fork.c", line 678
> ddb{6}> mach ddbcpu 0
> 
> After pressing enter here, the machine locked up completely.

It's hard for me to tell what's going on.  I believe the interesting
trace is the one from cpu0 that we don't have.  Can you easily reproduce
this?  I'm trying on amd64 without luck.  I'd glad if you could gather
more infos.

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