Comment 3 for bug 1611360

OK, I've verified I can reproduce the segfault with a 32-bit i386 xenial kvm guest. Much futzing around to get the scsi multipathing working, I'll doc that when I get a chance so I can reproduce, but wanted to document the test results and make my fix available via PPA for others.

Before fix:

ubuntu@x32multipath:~$ sudo multipathd -k
multipathd> show paths
ubuntu@x32multipath:~$

But, dmesg shows the segfault:

[ 142.603813] scsi 2:0:0:0: Direct-Access QEMU QEMU HARDDISK 2.5+ PQ: 0 ANSI: 5
[ 142.605344] sd 2:0:0:0: Attached scsi generic sg0 type 0
[ 142.605744] sd 2:0:0:0: [sda] 40960 512-byte logical blocks: (21.0 MB/20.0 MiB)
[ 142.606901] sd 2:0:0:0: [sda] Write Protect is off
[ 142.606908] sd 2:0:0:0: [sda] Mode Sense: 63 00 00 08
[ 142.607054] sd 2:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 142.610992] sda: sda1
[ 142.611780] sd 2:0:0:0: [sda] Attached SCSI disk
[ 151.914198] scsi 2:0:0:1: Direct-Access QEMU QEMU HARDDISK 2.5+ PQ: 0 ANSI: 5
[ 151.917004] sd 2:0:0:1: Attached scsi generic sg1 type 0
[ 151.917385] sd 2:0:0:1: [sdb] 40960 512-byte logical blocks: (21.0 MB/20.0 MiB)
[ 151.917755] sd 2:0:0:1: [sdb] Write Protect is off
[ 151.917764] sd 2:0:0:1: [sdb] Mode Sense: 63 00 00 08
[ 151.917864] sd 2:0:0:1: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 151.920866] sdb: sdb1
[ 151.921576] sd 2:0:0:1: [sdb] Attached SCSI disk
[ 151.975052] device-mapper: multipath round-robin: version 1.0.0 loaded
[ 213.768916] show_signal_msg: 12 callbacks suppressed
[ 213.768929] multipathd[670]: segfault at 0 ip b761b7cd sp b71c6040 error 4 in libmultipath.so.0[b75f9000+45000]

^^^^ blows up as per submitter ^^^

After update with fix:

ubuntu@x32multipath:~$ sudo multipathd -k
multipathd> show paths
hcil dev dev_t pri dm_st chk_st dev_st next_check
2:0:0:0 sda 8:0 1 active ready running XXXX...... 4/10
2:0:0:1 sdb 8:16 1 active ready running XXXXX..... 5/10
multipathd>

So, looking good. Will get back to this next week.

If anyone else seeing this problem is interested in testing the fix:

Available via PPA (has yakkety and xenial, but I've only tested xenial):

sudo add-apt-repository ppa:jgrimm/multipath-1611360
sudo apt-get update
sudo apt-get upgrade

cheers,