From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Andrea Righi <andrea.righi@canonical.com>,
        Nicholas Piggin <npiggin@gmail.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Oleg Nesterov <oleg@redhat.com>, linuxppc-dev@lists.ozlabs.org,
        linux-kernel@vger.kernel.org
Subject: Re: boot regression on ppc64 with linux 6.2
In-Reply-To: <ZA7oJr1/Z4vzWy4N@righiandr-XPS-13-7390>
References: <ZA7oJr1/Z4vzWy4N@righiandr-XPS-13-7390>
Date:   Wed, 15 Mar 2023 14:30:53 +1100
Message-ID: <878rfyofma.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Andrea Righi <andrea.righi@canonical.com> writes:
> I'm triggering the following bug when booting my qemu powerpc VM:

I'm not seeing that here :/

Can you give a bit more detail?
 - qemu version
 - qemu command line
 - what userspace are you using?
 - full dmesg of the failing case

> event-sources: Unable to request interrupt 23 for /event-sources/hot-plug-events
> WARNING: CPU: 0 PID: 1 at arch/powerpc/platforms/pseries/event_sources.c:26 request_event_sources_irqs+0xbc/0xf0
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W          6.2.2-kc #1
> Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,HEAD pSeries
> NIP:  c000000002022eec LR: c000000002022ee8 CTR: 0000000000000000
> REGS: c000000003483910 TRAP: 0700   Tainted: G        W           (6.2.2-kc)
> MSR:  8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE>  CR: 24483200  XER: 00000000
> CFAR: c000000000180838 IRQMASK: 0 
> GPR00: c000000002022ee8 c000000003483bb0 c000000001a5ce00 0000000000000050 
> GPR04: c000000002437d78 c000000002437e28 0000000000000001 0000000000000001 
> GPR08: c000000002437d00 0000000000000001 0000000000000000 0000000044483200 
> GPR12: 0000000000000000 c000000002720000 c000000000012758 0000000000000000 
> GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
> GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
> GPR24: 0000000000000000 c0000000020033fc cccccccccccccccd c0000000000e07f0 
> GPR28: c000000000db0520 0000000000000000 c0000000fff92ac0 0000000000000017 
> NIP [c000000002022eec] request_event_sources_irqs+0xbc/0xf0
> LR [c000000002022ee8] request_event_sources_irqs+0xb8/0xf0
> Call Trace:
> [c000000003483bb0] [c000000002022ee8] request_event_sources_irqs+0xb8/0xf0 (unreliable)
> [c000000003483c40] [c000000002022fa0] __machine_initcall_pseries_init_ras_hotplug_IRQ+0x80/0xb0
> [c000000003483c70] [c0000000000121b8] do_one_initcall+0x98/0x300
> [c000000003483d50] [c000000002004b28] kernel_init_freeable+0x2ec/0x370
> [c000000003483df0] [c000000000012780] kernel_init+0x30/0x190
> [c000000003483e50] [c00000000000cf5c] ret_from_kernel_thread+0x5c/0x64
> --- interrupt: 0 at 0x0
>
> I did a bisect it and it seems that the offending commit is:
> baa49d81a94b ("powerpc/pseries: hvcall stack frame overhead")
>
> Reverting that and also dfecd06bc552 ("powerpc: remove
> STACK_FRAME_OVERHEAD"), because we need to re-introduce
> STACK_FRAME_OVERHEAD, seems to fix everything.

That function doesn't make a hcall, so presumably there was some earlier
problem which we only detect here.

cheers