The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
Thanks, Sasha
------------------ original commit in Linus's tree ------------------
From 5580e96dad5a439d561d9648ffcbccb739c2a120 Mon Sep 17 00:00:00 2001 From: Michael Ellerman mpe@ellerman.id.au Date: Thu, 15 Feb 2024 00:14:04 +1100 Subject: [PATCH] powerpc/smp: Adjust nr_cpu_ids to cover all threads of a core
If nr_cpu_ids is too low to include at least all the threads of a single core adjust nr_cpu_ids upwards. This avoids triggering odd bugs in code that assumes all threads of a core are available.
Cc: stable@vger.kernel.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://msgid.link/20231229120107.2281153-1-mpe@ellerman.id.au --- arch/powerpc/kernel/prom.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c index 0b5878c3125b1..58e80076bed5c 100644 --- a/arch/powerpc/kernel/prom.c +++ b/arch/powerpc/kernel/prom.c @@ -375,6 +375,12 @@ static int __init early_init_dt_scan_cpus(unsigned long node, if (IS_ENABLED(CONFIG_PPC64)) boot_cpu_hwid = be32_to_cpu(intserv[found_thread]);
+ if (nr_cpu_ids % nthreads != 0) { + set_nr_cpu_ids(ALIGN(nr_cpu_ids, nthreads)); + pr_warn("nr_cpu_ids was not a multiple of threads_per_core, adjusted to %d\n", + nr_cpu_ids); + } + /* * PAPR defines "logical" PVR values for cpus that * meet various levels of the architecture: