Re: [PATCH] powerpc/970: fix nap return address corruption on async interrupt exit

[Madhavan Srinivasan <maddy@linux.ibm.com>]

On 7/29/26 2:27 PM, Thorsten Leemhuis wrote:
> On 7/23/26 13:52, John Ogness wrote:
>> On 2026-07-16, John Ogness <john.ogness@linutronix.de> wrote:
>>> On 2026-07-07, "Mukesh Kumar Chaurasiya (IBM)" <mkchauras@gmail.com> wrote:
>>>> On PowerMac G5 (PPC970, CONFIG_PPC_970_NAP) the system panics shortly
>>>> after boot with symptoms including instruction fetch faults, kernel data
>>>> access faults, and stack corruption, predominantly on SMP and always
>>>> somewhere inside softirq processing.
>>>> [...]
>>>> Fix this by calling nap_adjust_return() inside DEFINE_INTERRUPT_HANDLER_ASYNC
>>>> immediately before irq_exit_rcu(), ensuring _TLF_NAPPING is cleared and
>>>> regs->NIP is adjusted before any code that can re-enable interrupts or
>>>> invoke softirqs runs.  Move the explanatory comment into
>>>> nap_adjust_return() itself and remove it from arch_interrupt_async_exit_prepare().
>>>>
>>>> Fixes: bee25f97ad24 ("powerpc: Enable GENERIC_ENTRY feature")
>>>> Closes: https://lore.kernel.org/all/87wlvazrdy.fsf@igel.home/
>>>> Reported-by: Andreas Schwab <schwab@linux-m68k.org>
>>>> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
>>> Tested-by: John Ogness <john.ogness@linutronix.de>
>> Is there a reason this is not being queued for 7.2? Without this fix,
>> PPC970 machines cannot boot 7.2.
> Wondering the same. Quick reminder: Linus afaik wants all regressions
> ideally be fixed by -rc6. So it would be good to get this mainlined
> within the next few days -- unless of course there is a reason why this
> fix is a bad idea. Is there?
I have added this to my fixes-test and will pull this as part of 
upcoming fixes PR
Maddy
>
> Ciao, Thorsten