Comment 0 for bug 1959529

== Comment: #0 - D. Gary Chapman <email address hidden> - 2022-01-26 12:43:25 ==
---Problem Description---
IBM IDAA customer exposes hypersocket page allocation failure on Ubuntu 20.04 based SSC

Contact Information = Gary Chapman (<email address hidden>)

---uname output---
5.4.0-73-generic #82-Ubuntu

Machine Type = IBM Z in IDAA SSC-mode lpar

---Debugger---
A debugger is not configured

----------

IBM SSC LEVEL: 4.1.5
IBM IDAA LEVEL: 7.5.6

On a client system we are observing this:

Jan 19 16:25:57 data5 kernel: kworker/u760:28: page allocation failure: order:0, mode:0xa20(GFP_ATOMIC), nodemask=(null),cpuset=/,mems_allowed=0
Jan 19 16:25:57 data5 kernel: CPU: 20 PID: 4137988 Comm: kworker/u760:28 Kdump: loaded Tainted: G OE 5.4.0-73-generic #82-Ubuntu
Jan 19 16:25:57 data5 kernel: Hardware name: IBM 8561 T01 727 (LPAR)
Jan 19 16:25:57 data5 kernel: Workqueue: kcryptd/253:11 kcryptd_crypt [dm_crypt]
Jan 19 16:25:57 data5 kernel: Call Trace:
Jan 19 16:25:57 data5 kernel: ([<0000006b6d63e092>] show_stack+0x7a/0xc0)
Jan 19 16:25:57 data5 kernel: [<0000006b6d64588a>] dump_stack+0x8a/0xb8
Jan 19 16:25:57 data5 kernel: [<0000006b6cfd8262>] warn_alloc+0xe2/0x160

IBM LTC Networking team has identified the upstream commit 714c9108851743bb718fbc1bfb81290f12a53854 as the root cause.

This patch shows up in the Ubuntu kernel source tree:
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/commit/?id=714c9108851743bb718fbc1bfb81290f12a53854
but has not been ported to Ubuntu 20.04 / kernel 5.4

IDAA on SSC requests backport to focal.