I have a workaround for this:
UBUNTU: SAUCE: riscv: Disable VMAP_STACK since it fails with efi
When VMAP_STACK is enabled, kernel threads have their stacks in the vmalloc
region.
So when The kworker responsible for handling efi work queue (efi_call_rts)
calls
efi_virtmap_load and then switch_mm, if the stack of the worker is in a
vmalloc
area not yet synchronized with efi_mm (since RISC-V lazily populates vmalloc
area), an attempt to access this stack will trigger a fault which can't be
resolved since when trying to save the context, a new trap will be
triggered and
so on.
So disable VMAP_STACK for now until we figure out the correct fix.
And I'm working on the proper fix which consists in synchronizing the
efi page table with the page table of the calling thread before
switching to efi mm.
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You received this bug notification because you are a member of Kernel
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https://bugs.launchpad.net/bugs/1967130
Title:
rcu_sched detected stalls on CPUs/tasks
Status in linux-riscv package in Ubuntu:
New
Bug description:
When running the riscv64 live installer
(https://cdimage.ubuntu.com/ubuntu-server/daily-live/20220330/jammy-
live-server-riscv64.iso) on the SiFive Unmatched board we reproducibly
see rcu_sched stalls related to accessing the UEFI runtime:
Mar 30 11:50:47 ubuntu-server kernel: [ 1313.451647] rcu: INFO: rcu_sched
detected stalls on CPUs/tasks:
Mar 30 11:50:47 ubuntu-server kernel: [ 1313.451673] rcu: 3-...0: (3
GPs behind) idle=d03/1/0x4000000000000000 softirq=85648/85648 fqs=7326
Mar 30 11:50:47 ubuntu-server kernel: [ 1313.451698] (detected by 0,
t=15002 jiffies, g=155853, q=1286)
Mar 30 11:50:47 ubuntu-server kernel: [ 1313.451712] Task dump for CPU 3:
Mar 30 11:50:47 ubuntu-server kernel: [ 1313.451720] task:kworker/u8:1
state:R running task stack: 0 pid: 3715 ppid: 2 flags:0x00000008
Mar 30 11:50:47 ubuntu-server kernel: [ 1313.451750] Workqueue: efi_rts_wq
efi_call_rts
Mar 30 11:50:47 ubuntu-server kernel: [ 1313.451777] Call Trace:
Mar 30 11:50:47 ubuntu-server kernel: [ 1313.451782] [<ffffffff809be1b6>]
__schedule+0x226/0x644
uname -a:
Linux ubuntu-server 5.15.0-1004-generic #4-Ubuntu SMP Wed Feb 9 18:17:33 UTC
2022 riscv64 riscv64 riscv64 GNU/Linux
---
ProblemType: Bug
Architecture: riscv64
DistroRelease: Ubuntu 22.04
Package: linux-image-generic 5.15.0.1004.4
PackageArchitecture: riscv64
ProcEnviron:
TERM=vt220
PATH=(custom, no user)
LANG=C.UTF-8
Uname: Linux 5.15.0-1004-generic riscv64
UserGroups: N/A
_MarkForUpload: True
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