From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 25 Oct 2022 21:38:21 +0200
Subject: x86/mm: Use mm_alloc() in poking_init()
Git-commit: 3f4c8211d982099be693be9aa7d6fc4607dff290
Patch-mainline: v6.2-rc1
References: bsc#1212448

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

Acked-by: Nikolay Borisov <nik.borisov@suse.com>
---
 arch/x86/mm/init.c         |    2 +-
 include/linux/sched/task.h |    1 -
 kernel/fork.c              |    5 -----
 3 files changed, 1 insertion(+), 7 deletions(-)

--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -790,7 +790,7 @@ void __init poking_init(void)
 	spinlock_t *ptl;
 	pte_t *ptep;

-	poking_mm = copy_init_mm();
+	poking_mm = mm_alloc();
 	BUG_ON(!poking_mm);

 	/*
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -88,7 +88,6 @@ extern void exit_itimers(struct task_str
 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 long kernel_wait4(pid_t, int __user *, int, struct rusage *);
 int kernel_wait(pid_t pid, int *stat);
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2448,11 +2448,6 @@ struct task_struct * __init fork_idle(in
 	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.