Re: [BUG] powerpc: userspace processes crash in ld64.so.2 when running recent linux-next kernels

[Christophe Leroy (CS GROUP)]

Le 11/08/2026 à 06:23, Venkat Rao Bagalkote a écrit :
> As part of debugging and suggested by Maddy, I reverted the following 
> commit:
>
>    263e5159e00a ("powerpc: Fix exit_flags field placement in pt_regs for 
> ptrace")
>
> and rebuilt/booted linux-next with only that change reverted.
>
> After booting the reverted kernel, I rebuilt the latest upstream kernel
> using the same userspace and toolchain. The build completed
> successfully and I did not observe any of the ld64.so.2 userspace
> segfaults that were previously seen during kernel compilation.
>
> Kernel used for testing:
>
>    7.2.0-rc5-next-20260731-00001-g79d9c1ce90a9
>
> Top of tree:
>
>    commit 79d9c1ce90a9873422ca4d6d0124a1d1c10a098c
>    Revert "powerpc: Fix exit_flags field placement in pt_regs for ptrace"
>
> The upstream kernel build completed successfully:
>
>    INSTALL /lib/modules/7.2.0-rc7/kernel/net/openvswitch/vport-gre.ko
>    DEPMOD  /lib/modules/7.2.0-rc7
>    INSTALL /boot
>
> Based on this testing, reverting commit 263e5159e00a appears to
> eliminate the random userspace crashes observed during kernel builds,
> suggesting that the issue may be related to that change.

But commit 263e5159e00a fixes commit d7a6797e0bc1 ("powerpc: add 
exit_flags field in pt_regs"), by reverting commit 263e5159e00a you 
re-introduce other bugs.

It's a bit difficult to see what commit 263e5159e00a is doing exactly, 
most of it is a revert of commit d7a6797e0bc1 but it does something 
instead. Need to see what remains with both commits applied.

Christophe