Public bug reported:
Hardware: MSI Bravo 15 A4DDR, AMD Ryzen APU with hybrid graphics
- iGPU: AMD Renoir (Radeon Vega, PCI 0000:08:00.0)
- dGPU: AMD Navi 14 (Radeon RX 5500M, PCI 0000:03:00.0)
Kernel: linux-image-generic-hwe-26.04, versions 7.0.0-27 and 7.0.0-28 (Xubuntu
26.04)
Previously stable on kernel 6.12.86 with no issues.
ISSUE 1 (confirmed, root-caused via kdump crash dump):
NULL pointer dereference at dc_allow_idle_optimizations_internal+0x20/0x3c0
[amdgpu],
address 00000000000000b4, triggered via workqueue call chain:
dm_ism_delayed_work_func -> amdgpu_dm_ism_commit_event ->
dm_ism_dispatch_power_state -> dm_ism_commit_idle_optimization_state ->
dc_allow_idle_optimizations_internal
This occurred during a PCI hot-remove test of the dGPU
(echo 1 > /sys/bus/pci/devices/0000:03:00.0/remove), where a background
Idle Power State (IPS) management workqueue raced against device teardown.
Full vmcore and dmesg captured via kdump-tools, available on request.
Workaround: booting with amdgpu.dcdebugmask=0x800 (DC_DISABLE_IPS) has
prevented recurrence of this specific crash signature for [X] days since
applying.
Note: amdgpu.dpm=0 was tried first as a broader workaround but caused a complete
boot failure (system would not reach the login screen / display never
initialized).
ISSUE 2 (unresolved, separate failure mode):
Independent of Issue 1, the system also experiences intermittent complete silent
hangs requiring a hard power-off/reboot - no kernel panic, no oops, no journal
entries logged near the freeze time, no watchdog trip, and kdump does NOT
trigger
(no crash dump produced). Journal logging simply stops abruptly with no
preceding
errors or warnings.
Pattern observed across ~10 occurrences over several weeks:
- Uptime before hang varies widely: as little as ~4 minutes after login,
up to 10+ hours of uptime.
- Frequently but not always correlates with Google Chrome being open/in use
(both idle background tabs and active text/article browsing, not
specifically video playback).
- Occurs on both kernel 7.0.0-27 and 7.0.0-28.
- Did not occur on kernel 6.12.86 prior to upgrade.
- Ruled out: RAM fault (memtest86+, ~13 hours run, one full pass completed,
0 errors). Chrome hardware acceleration disabled did not prevent recurrence.
amdgpu.dcdebugmask=0x800 (applied for Issue 1) has not prevented recurrence.
Requesting guidance on further diagnostics to capture Issue 2, since standard
kdump/journald logging does not capture any trace of this hang.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-28-generic 7.0.0-28.28
ProcVersionSignature: Ubuntu 7.0.0-28.28-generic 7.0.12
Uname: Linux 7.0.0-28-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: bosha 5400 F.... wireplumber
/dev/snd/controlC0: bosha 5400 F.... wireplumber
/dev/snd/seq: bosha 5387 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: XFCE
Date: Sun Aug 2 13:51:58 2026
InstallationDate: Installed on 2026-04-24 (100 days ago)
InstallationMedia: Xubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
MachineType: Micro-Star International Co., Ltd. Bravo 15 A4DDR
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB:
0 amdgpudrmfb
1 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-28-generic
root=UUID=54f59859-2b42-4007-8746-3db7be7a25fb ro quiet splash
crashkernel=384M-:128M amdgpu.dcdebugmask=0x800
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/12/2026
dmi.bios.release: 1.22
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: E16WKAMS.116
dmi.board.asset.tag: Default string
dmi.board.name: MS-16WK
dmi.board.vendor: Micro-Star International Co., Ltd.
dmi.board.version: REV:1.0
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 10
dmi.chassis.vendor: Micro-Star International Co., Ltd.
dmi.chassis.version: Default string
dmi.modalias:
dmi:bvnAmericanMegatrendsInc.:bvrE16WKAMS.116:bd02/12/2026:br1.22:svnMicro-StarInternationalCo.,Ltd.:pnBravo15A4DDR:pvrREV1.0:rvnMicro-StarInternationalCo.,Ltd.:rnMS-16WK:rvrREV1.0:cvnMicro-StarInternationalCo.,Ltd.:ct10:cvrDefaultstring:sku16WK.1:pfaBr:
dmi.product.family: Br
dmi.product.name: Bravo 15 A4DDR
dmi.product.sku: 16WK.1
dmi.product.version: REV:1.0
dmi.sys.vendor: Micro-Star International Co., Ltd.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute
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https://bugs.launchpad.net/bugs/2162679
Title:
amdgpu: NULL pointer dereference in
dc_allow_idle_optimizations_internal via dm_ism_delayed_work_func (IPS
race), plus separate unexplained silent full-system hangs on kernel
7.0.0-27/28
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