Re: kern/56932: x68k frequently hangs up after uvm change in 9.99.75

[Tetsuya Isaki <isaki%pastel-flower.jp@localhost>]

At Mon, 18 Jul 2022 10:35:01 +0000 (UTC),
Chuck Silvers wrote:
>  this system has very very little RAM, so I'll guess that the hang
>  is because the system can't allocate memory.  in ddb, please do
>  "show uvmexp" and look at the number of free pages, eg.:
:
>  is the pagedaemon thread running after you notice the hang?

5 free pages, and pagedaemon seems stuck.
This is hand-copied.

|Stopped in pid 0.2 (system) at  netbsd:cpu_Debugger+0x6:    unlk a6
|db> show uvmexp
|Current UVM status:
|  pagesize=4096 (0x1000), pagemask=0xfff, pageshift=12, ncolors=1
|  2125 VM pages: 950 active, 55 inactive, 0 wired, 5 free
|  pages  558 anon, 177 file, 301 exec
|  freemin=32, free-target=42, wired-max=708
|  resv-pg=1, resv-kernel=5
|  bootpages=34, poolpages=868
|  faults=26552, traps=30585, intrs=77868, ctxswitch=29271
|   softint=13661, syscalls=115885
|  fault counts:
|    noram=10, noanon=0, pgwait=0, pgrele=0
|    ok relocks(total)=1725(1725), anget(retrys)=7103(177), amapcopy=3079
|    neighbor anon/obj pg=4799/34053, gets(lock/unlock)=13543/1549
|    cases: anon=4142, anoncow=2961, obj=11586, prcopy=1954, przero=5543
|  daemon and swap counts:
|    woke=46, revs=46, scans=12621, obscans=2674, anscans=306
|    busy=0, freed=2980, reactivate=1605, deactivate=12304
|    pageouts=22, pending=279, nswget=177
|    nswapdev=2, swpgavail=37098
|    swpages=37098, swpginuse=192, swpgonly=72, paging=0
|db> c

waited 10~15 seconds and then pressed NMI again.

|Got a keyboard NMI
|Stopped in pid 0.2 (system) at  netbsd:cpu_Debugger+0x6:    unlk a6
|db> show uvmexp

2nd "show uvmexp" differs only about interrupts, all others are the same.
-  faults=26552, traps=30585, intrs=77868, ctxswitch=29271
-   softint=13661, syscalls=115885
+  faults=26552, traps=30585, intrs=79782, ctxswitch=29854
+   softint=13913, syscalls=115885

>  please show a ddb stack trace from the
>  pagedaemon thread to confirm this.

Is this correct stack trace of pagedaemon?
|db> ps
|PID   LID S CPU   FLAGS    STRUCT LWP *          NAME WAIT
|:
|0      54 3   0     200          8ab440      pgdaemon tstile
|:
|db> trace/a 8ab440
|trace: pid 0 lid 54 at 0x39abdc8
|mi_switch(8ab440,7f7fbc,2d2700,8ab440,15c7be) + 2aa
|db>

Thanks,
---
Tetsuya Isaki <isaki%pastel-flower.jp@localhost / isaki%NetBSD.org@localhost>