[PATCH 6.1 217/219] LoongArch/smp: Call rcutree_report_cpu_starting() at tlb_init()

Greg Kroah-Hartman
2024-02-03T04:11:14Z

From: Huacai Chen <chenhuacai@loongson.cn>

commit 5056c596c3d1848021a4eaa76ee42f4c05c50346 upstream.

Machines which have more than 8 nodes fail to boot SMP after commit
a2ccf46333d7b2cf96 ("LoongArch/smp: Call rcutree_report_cpu_starting()
earlier"). Because such machines use tlb-based per-cpu base address
rather than dmw-based per-cpu base address, resulting per-cpu variables
can only be accessed after tlb_init(). But rcutree_report_cpu_starting()
is now called before tlb_init() and accesses per-cpu variables indeed.

Since the original patch want to avoid the lockdep warning caused by
page allocation in tlb_init(), we can move rcutree_report_cpu_starting()
to tlb_init() where after tlb exception configuration but before page
allocation.

Fixes: a2ccf46333d7b2cf96 ("LoongArch/smp: Call rcutree_report_cpu_starting() earlier")
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/loongarch/kernel/smp.c | 1 -
arch/loongarch/mm/tlb.c | 16 ++++++++++------
2 files changed, 10 insertions(+), 7 deletions(-)

--- a/arch/loongarch/kernel/smp.c
+++ b/arch/loongarch/kernel/smp.c
@@ -473,7 +473,6 @@ asmlinkage void start_secondary(void)
sync_counter();
cpu = raw_smp_processor_id();
set_my_cpu_offset(per_cpu_offset(cpu));
- rcu_cpu_starting(cpu);

cpu_probe();
constant_clockevent_init();
--- a/arch/loongarch/mm/tlb.c
+++ b/arch/loongarch/mm/tlb.c
@@ -271,12 +271,16 @@ void setup_tlb_handler(int cpu)
set_handler(EXCCODE_TLBNR * VECSIZE, handle_tlb_protect, VECSIZE);
set_handler(EXCCODE_TLBNX * VECSIZE, handle_tlb_protect, VECSIZE);
set_handler(EXCCODE_TLBPE * VECSIZE, handle_tlb_protect, VECSIZE);
- }
+ } else {
+ int vec_sz __maybe_unused;
+ void *addr __maybe_unused;
+ struct page *page __maybe_unused;
+
+ /* Avoid lockdep warning */
+ rcu_cpu_starting(cpu);
+
#ifdef CONFIG_NUMA
- else {
- void *addr;
- struct page *page;
- const int vec_sz = sizeof(exception_handlers);
+ vec_sz = sizeof(exception_handlers);

if (pcpu_handlers[cpu])
return;
@@ -292,8 +296,8 @@ void setup_tlb_handler(int cpu)
csr_write64(pcpu_handlers[cpu], LOONGARCH_CSR_EENTRY);
csr_write64(pcpu_handlers[cpu], LOONGARCH_CSR_MERRENTRY);
csr_write64(pcpu_handlers[cpu] + 80*VECSIZE, LOONGARCH_CSR_TLBRENTRY);
- }
#endif
+ }
}

void tlb_init(int cpu)