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. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-riscv in Ubuntu. 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 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-riscv/+bug/1967130/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp