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Date:      Sat, 2 May 2020 18:46:54 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        "vangyzen@freebsd.org " <vangyzen@FreeBSD.org>, svn-src-head@freebsd.org, FreeBSD Current <freebsd-current@freebsd.org>, FreeBSD Hackers <freebsd-hackers@freebsd.org>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org>
Subject:   Re: svn commit: r360233 - in head: contrib/jemalloc . . . : This partially breaks a 2-socket 32-bit powerpc (old PowerMac G4) based on head -r360311
Message-ID:  <C24EE1A1-FAED-42C2-8204-CA7B1D20A369@yahoo.com>
References:  <C24EE1A1-FAED-42C2-8204-CA7B1D20A369.ref@yahoo.com>

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[I'm only claiming the new jemalloc is involved and that
reverting avoids the problem.]

I've been reporting to some lists problems with:

dhclient
sendmail
rpcbind
mountd
nfsd

getting SIGSEGV (signal 11) crashes and some core
dumps on the old 2-socket (1 core per socket) 32-bit
PowerMac G4 running head -r360311.

Mika=C3=ABl Urankar sent a note suggesting that I try
testing reverting head -r360233 for my head -r360311
context. He got it right . . .


Context:

The problem was noticed by an inability to have
other machines do a:

mount -onoatime,soft OLDPOWERMAC-LOCAL-IP:/... /mnt

sort of operation and to have succeed. By contrast, on
the old PowerMac G4 I could initiate mounts against
other machines just fine.

I do not see any such problems on any of (all based
on head -r360311):

powerpc64 (old PowerMac G5 2-sockets with 2 cores each)
armv7 (OrangePi+ 2ed)
aarch64 (Rock64, RPi4, RPi3,
         OverDrive 1000,
         Macchiatobin Double Shot)
amd64 (ThreadRipper 1950X)

So I expect something 32-bit powerpc specific
is somehow involved, even if jemalloc is only
using whatever it is.

(A kyua run with a debug kernel did not find other
unexpected signal 11 sources on the 32-bit PowerMac
compared to past kyua runs, at least that I noticed.
There were a few lock order reversals that I do not
know if they are expected or known-safe or not.
I've reported those reversals to the lists as well.)


Recent experiments based on the suggestion:

Doing the buildworld, buildkernel and installing just
the new kernel and rebooting made no difference.

But then installing the new world and rebooting did
make things work again: I no longer get core files
for the likes of (old cores from before the update):

# find / -name "*.core" -print
/var/spool/clientmqueue/sendmail.core
/rpcbind.core
/mountd.core
/nfsd.core

Nor do I see the various notices for sendmail
signal 11's that did not leave behind a core file
--or for dhclient (no core file left behind).
And I can mount the old PowerMac's drive from
other machines just fine.


Other notes:

I do not actively use sendmail but it was left
to do its default things, partially to test if
such default things are working. Unfortunately,
PowerMacs have a problematical status under
FreeBSD and my context has my historical
experiments with avoiding various problems.

=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)




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