x86/mm: Use mm_alloc() in poking_init()

Instead of duplicating init_mm, allocate a fresh mm. The advantage is
that mm_alloc() has much simpler dependencies. Additionally it makes
more conceptual sense, init_mm has no (and must not have) user state
to duplicate.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221025201057.816175235@infradead.org

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 9121bc1..d398735 100644 (file)
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -801,7 +801,7 @@ void __init poking_init(void)
        spinlock_t *ptl;
        pte_t *ptep;
 
-       poking_mm = copy_init_mm();
+       poking_mm = mm_alloc();
        BUG_ON(!poking_mm);
 
        /*

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 8431558..357e006 100644 (file)
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -91,7 +91,6 @@ extern void exit_itimers(struct task_struct *);
 extern pid_t kernel_clone(struct kernel_clone_args *kargs);
 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
 struct task_struct *fork_idle(int);
-struct mm_struct *copy_init_mm(void);
 extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
 extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);

diff --git a/kernel/fork.c b/kernel/fork.c
index 451ce80..6142c58 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2592,11 +2592,6 @@ struct task_struct * __init fork_idle(int cpu)
        return task;
 }
 
-struct mm_struct *copy_init_mm(void)
-{
-       return dup_mm(NULL, &init_mm);
-}
-
 /*
  * This is like kernel_clone(), but shaved down and tailored to just
  * creating io_uring workers. It returns a created task, or an error pointer.