csdlock_debug is a early_param to enable csd_lock_wait
feature.
It uses static_branch_enable in early_param which triggers
a panic on arm64 with config:
CONFIG_SPARSEMEM=y
CONFIG_SPARSEMEM_VMEMMAP=n
The log shows:
Unable to handle kernel NULL pointer dereference at
virtual address ", '0' <repeats 16 times>, "
...
Call trace:
__aarch64_insn_write+0x9c/0x18c
...
static_key_enable+0x1c/0x30
csdlock_debug+0x4c/0x78
do_early_param+0x9c/0xcc
parse_args+0x26c/0x3a8
parse_early_options+0x34/0x40
parse_early_param+0x80/0xa4
setup_arch+0x150/0x6c8
start_kernel+0x8c/0x720
...
Kernel panic - not syncing: Oops: Fatal exception
Call trace inside __aarch64_insn_write:
__nr_to_section
__pfn_to_page
phys_to_page
patch_map
__aarch64_insn_write
Here, with CONFIG_SPARSEMEM_VMEMMAP=n, __nr_to_section returns
NULL and makes the NULL dereference because mem_section is
initialized in sparse_init after parse_early_param stage.
So, static_branch_enable shouldn't be used inside early_param.
To avoid this, I changed it to __setup and fixed this.
Reported-by: Chen jingwen <chenjingwen6@xxxxxxxxxx>
Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
---
Change v2 -> v3:
Add module name in title
Change v1 -> v2:
Fix return 1 for __setup
---
kernel/smp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index 65a630f62363..381eb15cd28f 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -174,9 +174,9 @@ static int __init csdlock_debug(char *str)
if (val)
static_branch_enable(&csdlock_debug_enabled);
- return 0;
+ return 1;
}
-early_param("csdlock_debug", csdlock_debug);
+__setup("csdlock_debug=", csdlock_debug);
static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
--
2.17.1
