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From:
Jeremie Courreges-Anglas <jca@wxcvbn.org>
Subject:
Re: Please test: parallel fault handling
To:
tech@openbsd.org
Date:
Thu, 22 May 2025 18:54:08 +0200

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On Mon, May 19, 2025 at 09:23:27PM +0200, Jeremie Courreges-Anglas wrote:
> On Tue, May 13, 2025 at 02:28:08PM +0200, Martin Pieuchot wrote:
> > On 13/05/25(Tue) 13:57, Jeremie Courreges-Anglas wrote:
> [...]
> > > The sparc64 LDOM went into two panics - I somehow managed to break it
> > > out of ddb after the first panic due to bogus conserver.  The data
> > > below is minimal, sorry, I didn't recover the full trace from dmesg
> > > after the 1st panic, and 'mach ddbcpu 0' locked up during the 2nd
> > > panic.
> > 
> > I wonder if sparc64's pmap is in need for some love...
> > 
> > > 
> > > I had not run a sparc64 bulk build on this machine in the recent
> > > months, and I don't know whether both panics are related to your diff,
> > > but I'll do my best to try and reproduce them.  Currently I've
> > > restarted the bulk build without the uvm change. Maybe someone with
> > > more sparc64 knowledge will bring some clue here.
> > 
> > Please let me know.
> 
> I can already tell that this LDOM ran the rest of the bulk with the
> parallel uvm fault diff reverted...  Now restarting another build from
> scratch, with your diff on top of -current.
> 
> > You can also start by "ps /o" or "show proc".
> 
> Hopefully that will be enough!  mach ddbcpu x didn't seem very usable.

*Bzzzt*

The same LDOM was busy compiling two devel/llvm copies under dpb(1).
Input welcome, I'm not sure yet what other ddb commands could help.

login: panic: trap type 0x34 (mem address not aligned): pc=1012f68 npc=1012f6c pstate=820006<PRIV,IE>
Stopped at      db_enter+0x8:   nop
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
  57488   1522      0        0x11          0    1  perl
 435923   9891     55   0x1000002          0    4  cc1plus
 135860  36368     55   0x1000002          0   13  cc1plus
 333743  96489     55   0x1000002          0    0  cc1plus
 433162  55422     55   0x1000002          0    9  cc1plus
 171658  49723     55   0x1000002          0    5  cc1plus
  47127  57536     55   0x1000002          0   10  cc1plus
  56600   9350     55   0x1000002          0   14  cc1plus
 159792  13842     55   0x1000002          0    6  cc1plus
 510019  10312     55   0x1000002          0    8  cc1plus
  20489  65709     55   0x1000002          0   15  cc1plus
 337455  42430     55   0x1000002          0   12  cc1plus
 401407  80906     55   0x1000002          0   11  cc1plus
  22993  62317     55   0x1000002          0    2  cc1plus
 114916  17058     55   0x1000002          0    7  cc1plus
*435412  33034      0     0x14000      0x200    3K pagedaemon
trap(400fe6b19b0, 34, 1012f68, 820006, 3, 42) at trap+0x334
Lslowtrap_reenter(40015a58a00, 77b5db2000, deadbeefdeadc0c7, 1d8, 2df0fc468, 468) at Lslowtrap_reenter+0xf8
pmap_page_protect(40010716ab8, c16, 1cc9860, 193dfa0, 1cc9000, 1cc9000) at pmap_page_protect+0x1fc
uvm_pagedeactivate(40010716a50, 40015a50d24, 18667a0, 0, 0, 1c8dac0) at uvm_pagedeactivate+0x54
uvmpd_scan_active(0, 0, 270f2, 18667a0, 0, ffffffffffffffff) at uvmpd_scan_active+0x150
uvm_pageout(400fe6b1e08, 55555556, 18667a0, 1c83f08, 1c83000, 1c8dc18) at uvm_pageout+0x2dc
proc_trampoline(0, 0, 0, 0, 0, 0) at proc_trampoline+0x10
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{3}>
ddb{3}>
ddb{3}> ps /o
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
  57488   1522      0        0x11          0    1  perl
 435923   9891     55   0x1000002          0    4  cc1plus
 135860  36368     55   0x1000002          0   13  cc1plus
 333743  96489     55   0x1000002          0    0  cc1plus
 433162  55422     55   0x1000002          0    9  cc1plus
 171658  49723     55   0x1000002          0    5  cc1plus
  47127  57536     55   0x1000002          0   10  cc1plus
  56600   9350     55   0x1000002          0   14  cc1plus
 159792  13842     55   0x1000002          0    6  cc1plus
 510019  10312     55   0x1000002          0    8  cc1plus
  20489  65709     55   0x1000002          0   15  cc1plus
 337455  42430     55   0x1000002          0   12  cc1plus
 401407  80906     55   0x1000002          0   11  cc1plus
  22993  62317     55   0x1000002          0    2  cc1plus
 114916  17058     55   0x1000002          0    7  cc1plus
*435412  33034      0     0x14000      0x200    3K pagedaemon
ddb{3}> show proc
PROC (pagedaemon) tid=435412 pid=33034 tcnt=1 stat=onproc
    flags process=14000<NOZOMBIE,SYSTEM> proc=200<SYSTEM>
    runpri=4, usrpri=50, slppri=4, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0x40015a50fc0,0x40015a50a90
    process=0x403c1f0ac70 user=0x400fe6ae000, vmspace=0x1c8e2c0
    estcpu=0, cpticks=0, pctcpu=0.0, user=0, sys=0, intr=0
ddb{3}> show uvm
Current UVM status:
  pagesize=8192 (0x2000), pagemask=0x1fff, pageshift=13
  2057215 VM pages: 1446170 active, 104107 inactive, 1 wired, 91303 free (91303 zero)
  freemin=68573, free-target=91430, inactive-target=516759, wired-max=685738
  faults=-1646139234, traps=-1346997425, intrs=709572514, ctxswitch=368458634 fpuswitch=7786655
  softint=86318616, syscalls=-1689153682, kmapent=12
  fault counts:
    noram=0, noanon=0, noamap=0, pgwait=0, pgrele=0
    relocks=6994201(335164), upgrades=1050667241(9720) anget(retries)=1162622063(0), amapcopy=302352908
    neighbor anon/obj pg=403857156/660172689, gets(lock/unlock)=442541030/7329374
    cases: anon=884461767, anoncow=278160296, obj=382612954, prcopy=59590377, przero=1044001823
  daemon and swap counts:
    woke=153, revs=153, scans=0, obscans=0, anscans=0
    busy=0, freed=0, reactivate=0, deactivate=411398
    pageouts=0, pending=0, nswget=0
    nswapdev=1
    swpages=2130619, swpginuse=0, swpgonly=0 paging=0
  kernel pointers:
    objs(kern)=0x1c2d7a0

-- 
jca