From: Ran Xiaokai Boot parameters prefixed with "sysctl." are processed during the final stage of system initialization via kernel_init()-> do_sysctl_args(). When CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled, the sysctl.vm.mem_profiling entry is not writable and will cause a warning. Before run_init_process(), system initialization executes in kernel thread context. Use current->mm to distinguish sysctl writes during do_sysctl_args() from user-space triggered ones. And when the proc_handler is from do_sysctl_args(), always return success because the same value was already set by setup_early_mem_profiling() and this eliminates a permission denied warning. Suggested-by: Suren Baghdasaryan Acked-by: Suren Baghdasaryan Signed-off-by: Ran Xiaokai --- lib/alloc_tag.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index 846a5b5b44a4..00ae4673a271 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -776,8 +776,22 @@ EXPORT_SYMBOL(page_alloc_tagging_ops); static int proc_mem_profiling_handler(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { - if (!mem_profiling_support && write) - return -EINVAL; + if (write) { + /* + * Call from do_sysctl_args() which is a no-op since the same + * value was already set by setup_early_mem_profiling. + * Return success to avoid warnings from do_sysctl_args(). + */ + if (!current->mm) + return 0; + +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG + /* User can't toggle profiling while debugging */ + return -EACCES; +#endif + if (!mem_profiling_support) + return -EINVAL; + } return proc_do_static_key(table, write, buffer, lenp, ppos); } @@ -787,11 +801,7 @@ static const struct ctl_table memory_allocation_profiling_sysctls[] = { { .procname = "mem_profiling", .data = &mem_alloc_profiling_key, -#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG - .mode = 0444, -#else .mode = 0644, -#endif .proc_handler = proc_mem_profiling_handler, }, }; -- 2.25.1