On Tue, Mar 07, 2023 at 05:41:50PM +0100, Ard Biesheuvel wrote:
> From: Pierre Gondois <pierre.gondois@xxxxxxx>
>
> [ Upstream commit 0e68b5517d3767562889f1d83fdb828c26adb24 ]
>
> Running a rt-kernel base on 6.2.0-rc3-rt1 on an Ampere Altra outputs
> the following:
> BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 9, name: kworker/u320:0
> preempt_count: 2, expected: 0
> RCU nest depth: 0, expected: 0
> 3 locks held by kworker/u320:0/9:
> #0: ffff3fff8c27d128 ((wq_completion)efi_rts_wq){+.+.}-{0:0}, at: process_one_work (./include/linux/atomic/atomic-long.h:41)
> #1: ffff80000861bdd0 ((work_completion)(&efi_rts_work.work)){+.+.}-{0:0}, at: process_one_work (./include/linux/atomic/atomic-long.h:41)
> #2: ffffdf7e1ed3e460 (efi_rt_lock){+.+.}-{3:3}, at: efi_call_rts (drivers/firmware/efi/runtime-wrappers.c:101)
> Preemption disabled at:
> efi_virtmap_load (./arch/arm64/include/asm/mmu_context.h:248)
> CPU: 0 PID: 9 Comm: kworker/u320:0 Tainted: G W 6.2.0-rc3-rt1
> Hardware name: WIWYNN Mt.Jade Server System B81.03001.0005/Mt.Jade Motherboard, BIOS 1.08.20220218 (SCP: 1.08.20220218) 2022/02/18
> Workqueue: efi_rts_wq efi_call_rts
> Call trace:
> dump_backtrace (arch/arm64/kernel/stacktrace.c:158)
> show_stack (arch/arm64/kernel/stacktrace.c:165)
> dump_stack_lvl (lib/dump_stack.c:107 (discriminator 4))
> dump_stack (lib/dump_stack.c:114)
> __might_resched (kernel/sched/core.c:10134)
> rt_spin_lock (kernel/locking/rtmutex.c:1769 (discriminator 4))
> efi_call_rts (drivers/firmware/efi/runtime-wrappers.c:101)
> [...]
>
> This seems to come from commit ff7a167961d1 ("arm64: efi: Execute
> runtime services from a dedicated stack") which adds a spinlock. This
> spinlock is taken through:
> efi_call_rts()
> \-efi_call_virt()
> \-efi_call_virt_pointer()
> \-arch_efi_call_virt_setup()
>
> Make 'efi_rt_lock' a raw_spinlock to avoid being preempted.
>
> [ardb: The EFI runtime services are called with a different set of
> translation tables, and are permitted to use the SIMD registers.
> The context switch code preserves/restores neither, and so EFI
> calls must be made with preemption disabled, rather than only
> disabling migration.]
>
> Fixes: ff7a167961d1 ("arm64: efi: Execute runtime services from a dedicated stack")
> Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v6.1+
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Now queued up, thanks.
greg k-h
