On 2022/5/10 17:46, Chen Zhongjin wrote:
csdlock_debug uses early_param and static_branch_enable() to enable csd_lock_wait feature, which triggers a panic on arm64 with config: CONFIG_SPARSEMEM=y CONFIG_SPARSEMEM_VMEMMAP=n
With CONFIG_SPARSEMEM_VMEMMAP=n, __nr_to_section is called in static_key_enable() and returns NULL which makes NULL dereference because mem_section is initialized in sparse_init() which is later than parse_early_param() stage.
For powerpc this is also broken, because early_param stage is earlier than jump_label_init() so static_key_enable won't work. powerpc throws an warning: "static key 'xxx' used before call to jump_label_init()".
Thus, early_param is too early for csd_lock_wait to run static_branch_enable(), so changes it to __setup to fix these.
Fixes: 8d0968cc6b8f ("locking/csd_lock: Add boot parameter for controlling CSD lock debugging") Cc: stable@vger.kernel.org Reported-by: Chen jingwen chenjingwen6@huawei.com Signed-off-by: Chen Zhongjin chenzhongjin@huawei.com
Change v3 -> v4: Fix title and description because this fix is also applied to powerpc. For more detailed arm64 bug report see: https://lore.kernel.org/linux-arm-kernel/e8715911-f835-059d-27f8-cc5f5ad30a0...
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);
Ping for review. Thanks！