fw_token is used for DT/ACPI systems to identify CPUs sharing caches. For DT based systems, fw_token is set to a pointer to a DT node.
Commit 22def0b492e6 ("arch_topology: Build cacheinfo from primary CPU") removed clearing of per_cpu_cacheinfo(cpu), which leads to reference underrun in cache_shared_cpu_map_remove() during repeated cpu offline/online as the reference is no longer incremented, because allocate_cache_info() is now skipped in the online path.
The same problem existed on upstream but had a different root cause, see 2613cc29c572 ("cacheinfo: Remove of_node_put() for fw_token").
Fixes the following splat: OF: ERROR: Bad of_node_put() on /cpus/l2-cache0 CPU: 3 PID: 29 Comm: cpuhp/3 Tainted: G O 6.1.159-arm64 #1 Hardware name: AXM56xx Victoria (DT) Call trace: dump_backtrace+0xd8/0x12c show_stack+0x1c/0x34 dump_stack_lvl+0x70/0x88 dump_stack+0x14/0x2c of_node_release+0x134/0x138 kobject_put+0xa8/0x21c of_node_put+0x1c/0x28 cache_shared_cpu_map_remove+0x19c/0x220 cacheinfo_cpu_pre_down+0x60/0xa0 cpuhp_invoke_callback+0x140/0x570 cpuhp_thread_fun+0xc8/0x19c smpboot_thread_fn+0x218/0x23c kthread+0x108/0x118 ret_from_fork+0x10/0x20
Fixes: 22def0b492e6 ("arch_topology: Build cacheinfo from primary CPU") Signed-off-by: Petr Malat oss@malat.biz --- drivers/base/cacheinfo.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c index 9e11d42b0d64..b57f64725f25 100644 --- a/drivers/base/cacheinfo.c +++ b/drivers/base/cacheinfo.c @@ -404,8 +404,6 @@ static void cache_shared_cpu_map_remove(unsigned int cpu) } } } - if (of_have_populated_dt()) - of_node_put(this_leaf->fw_token); }
/* cpu is no longer populated in the shared map */