Excerpts from Michael Ellerman's message of June 15, 2021 11:44 pm:
> Nicholas Piggin <npig...@gmail.com> writes:
>> diff --git a/arch/powerpc/lib/feature-fixups.c
>> b/arch/powerpc/lib/feature-fixups.c
>> index fe26f2fa0f3f..fbe94e2d5011 100644
>> --- a/arch/powerpc/lib/feature-fixups.c
>> +++ b/arch/powerpc/lib/feature-fixups.c
>> @@ -412,12 +430,19 @@ void do_entry_flush_fixups(enum l1d_flush_type types)
>> stop_machine(__do_entry_flush_fixups, &types, NULL);
>> }
>>
>> -void do_rfi_flush_fixups(enum l1d_flush_type types)
>> +static int __do_rfi_flush_fixups(void *data)
>> {
>> + enum l1d_flush_type types = *(enum l1d_flush_type *)data;
>> unsigned int instrs[3], *dest;
>> long *start, *end;
>> int i;
>>
>> + if (types & L1D_FLUSH_FALLBACK)
>> + rfi_exit_not_reentrant = true;
>> + else
>> + rfi_exit_not_reentrant = false;
>> + update_interrupt_exit();
>
> This is not happy:
Ah, needs a static_key_enable_cpuslocked. I'll fix.
Thanks,
Nick
>
> [ 0.000000][ T0] ============================================
> [ 0.000000][ T0] WARNING: possible recursive locking detected
> [ 0.000000][ T0] 5.13.0-rc2-00118-gca433a3a44e3 #1 Not tainted
> [ 0.000000][ T0] --------------------------------------------
> [ 0.000000][ T0] swapper/0 is trying to acquire lock:
> [ 0.000000][ T0] c00000000252fa10 (cpu_hotplug_lock){....}-{0:0}, at:
> static_key_enable+0x24/0x50
> [ 0.000000][ T0]
> [ 0.000000][ T0] but task is already holding lock:
> [ 0.000000][ T0] c00000000252fa10 (cpu_hotplug_lock){....}-{0:0}, at:
> stop_machine+0x2c/0x60
> [ 0.000000][ T0]
> [ 0.000000][ T0] other info that might help us debug this:
> [ 0.000000][ T0] Possible unsafe locking scenario:
> [ 0.000000][ T0]
> [ 0.000000][ T0] CPU0
> [ 0.000000][ T0] ----
> [ 0.000000][ T0] lock(cpu_hotplug_lock);
> [ 0.000000][ T0] lock(cpu_hotplug_lock);
> [ 0.000000][ T0]
> [ 0.000000][ T0] *** DEADLOCK ***
> [ 0.000000][ T0]
> [ 0.000000][ T0] May be due to missing lock nesting notation
> [ 0.000000][ T0]
> [ 0.000000][ T0] 1 lock held by swapper/0:
> [ 0.000000][ T0] #0: c00000000252fa10 (cpu_hotplug_lock){....}-{0:0},
> at: stop_machine+0x2c/0x60
> [ 0.000000][ T0]
> [ 0.000000][ T0] stack backtrace:
> [ 0.000000][ T0] CPU: 0 PID: 0 Comm: swapper Not tainted
> 5.13.0-rc2-00118-gca433a3a44e3 #1
> [ 0.000000][ T0] Call Trace:
> [ 0.000000][ T0] [c0000000027db8f0] [c00000000093dd28]
> dump_stack+0xec/0x144 (unreliable)
> [ 0.000000][ T0] [c0000000027db940] [c0000000001ed5b4]
> __lock_acquire+0x1744/0x28b0
> [ 0.000000][ T0] [c0000000027dba70] [c0000000001ef338]
> lock_acquire+0x128/0x600
> [ 0.000000][ T0] [c0000000027dbb70] [c00000000015035c]
> cpus_read_lock+0x4c/0x170
> [ 0.000000][ T0] [c0000000027dbba0] [c0000000003c2594]
> static_key_enable+0x24/0x50
> [ 0.000000][ T0] [c0000000027dbbd0] [c0000000000ae87c]
> __do_rfi_flush_fixups+0x7c/0x300
> [ 0.000000][ T0] [c0000000027dbc80] [c0000000002ab7e4]
> stop_machine_cpuslocked+0xe4/0x200
> [ 0.000000][ T0] [c0000000027dbcf0] [c0000000002ab940]
> stop_machine+0x40/0x60
> [ 0.000000][ T0] [c0000000027dbd30] [c0000000000aef30]
> do_rfi_flush_fixups+0x30/0x50
> [ 0.000000][ T0] [c0000000027dbd60] [c000000000040890]
> setup_rfi_flush+0xa0/0x140
> [ 0.000000][ T0] [c0000000027dbdd0] [c00000000201c6c4]
> pnv_setup_arch+0x304/0x4ac
> [ 0.000000][ T0] [c0000000027dbe60] [c00000000200a31c]
> setup_arch+0x374/0x3c4
> [ 0.000000][ T0] [c0000000027dbee0] [c000000002003d08]
> start_kernel+0xb0/0x790
> [ 0.000000][ T0] [c0000000027dbf90] [c00000000000d79c]
> start_here_common+0x1c/0x600
> [ 0.000000][ T0] rfi-flush: patched 12 locations (fallback displacement
> flush)
>
>
> cheers
>
