在 2024/1/25 15:31, Mike Rapoport 写道:
On Wed, Jan 24, 2024 at 09:19:00AM -0800, Lameter, Christopher wrote:
On Tue, 23 Jan 2024, Huang Shijie wrote:
During the kernel booting, the generic cpu_to_node() is called too early in
arm64, powerpc and riscv when CONFIG_NUMA is enabled.
For arm64/powerpc/riscv, there are at least four places in the common code
where the generic cpu_to_node() is called before it is initialized:
1.) early_trace_init() in kernel/trace/trace.c
2.) sched_init() in kernel/sched/core.c
3.) init_sched_fair_class() in kernel/sched/fair.c
4.) workqueue_init_early() in kernel/workqueue.c
In order to fix the bug, the patch changes generic cpu_to_node to
function pointer, and export it for kernel modules.
Introduce smp_prepare_boot_cpu_start() to wrap the original
smp_prepare_boot_cpu(), and set cpu_to_node with early_cpu_to_node.
Introduce smp_prepare_cpus_done() to wrap the original smp_prepare_cpus(),
and set the cpu_to_node to formal _cpu_to_node().
Would you please fix this cleanly without a function pointer?
What I think needs to be done is a patch series.
1. Instrument cpu_to_node so that some warning is issued if it is used too
early. Preloading the array with NUMA_NO_NODE would allow us to do that.
2. Implement early_cpu_to_node on platforms that currently do not have it.
3. A series of patches that fix each place where cpu_to_node is used too
early.
For step 3, I find it it hard to change the cpu_to_node() to
early_cpu_to_node() for early_trace_init().
In early_trace_init(), the __ring_buffer_alloc() calls the cpu_to_node().
In order to fix the bug, we should use early_cpu_to_node() for
__ring_buffer_alloc().
But __ring_buffer_alloc() is also used by the kernel after the booting
finished.
After the booting finishes, we should use the cpu_to_node(), not the
early_cpu_to_node().
I think step 3 can be simplified with a generic function that sets
per_cpu(numa_node) using early_cpu_to_node(). It can be called right after
setup_per_cpu_areas().
I think this method maybe better..
I will try this too.
Thanks
Huang Shijie
