In a discussion with Andreas we failed to break it in his environment but it reliably failed in mine. Then I found the crash in dmesg, there it looks like this:
[2431454.082712] User process fault: interruption code 003b ilc:2 in clustalo[2aa2d000000+d4000] [2431454.082725] Failing address: 000000002d0d5000 TEID: 000000002d0d5800 [2431454.082727] Fault in primary space mode while using user ASCE. [2431454.082729] AS:0000000e6fcb41c7 R3:0000000000000024 [2431454.082734] CPU: 3 PID: 1359979 Comm: clustalo Tainted: P O 5.4.0-51-generic #56-Ubuntu [2431454.082735] Hardware name: IBM 2964 N63 400 (LPAR) [2431454.082737] User PSW : 0705200180000000 000002aa2d011028 [2431454.082739] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:1 AS:0 CC:2 PM:0 RI:0 EA:3 [2431454.082741] User GPRS: 000003ff00000018 0000000000000002 000000002d0d5560 000002aa2d0ba8e4 [2431454.082742] 000002aa2d0ba8e4 0000000000000007 0000000000000019 000000002d0d5560 [2431454.082743] 0000000000000000 000003ff00000001 000002aa2edaef70 000003ff8a6767a0 [2431454.082744] 000003ff8a62bf98 000002aa2d0baa80 000002aa2d01a130 000003ffcabfc350 [2431454.082753] User Code: 000002aa2d01101a: b9040013 lgr %r1,%r3 000002aa2d01101e: d207f0c0b028 mvc 192(8,%r15),40(%r11) #000002aa2d011024: b9040034 lgr %r3,%r4 >000002aa2d011028: 584020c0 l %r4,192(%r2) 000002aa2d01102c: 1941 cr %r4,%r1 000002aa2d01102e: a7240022 brc 2,000002aa2d011072 000002aa2d011032: eb110003000d sllg %r1,%r1,3 000002aa2d011038: b9080021 agr %r2,%r1 [2431454.082765] Last Breaking-Event-Address: [2431454.082770] [<000002aa2d01a12a>] 0x2aa2d01a12a -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1903817 Title: Clustalo 1.2.4-6 segfaults on s390x To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1903817/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs