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>
[mkoutny: Add explicit sched/mm.h include to fix SLE15-SP5 build.
 The SLE15-SP4 works because sched/mm.h gets included somehow via bpf.h and
 some of the commits
   git log --oneline -G"include.*bpf\.h" origin/SLE15-SP4..origin/SLE15-SP5 -- include
 are suspicious. The upstream kernel includes sched/mm.h accidentally via
 xarray.h from 1dd685c414a7. Instead of reverse engineering the history of
 includes be explicit and include it where needed.
]
---
 arch/x86/mm/init.c         |    3 ++-
 include/linux/sched/task.h |    1 -
 kernel/fork.c              |    5 -----
 3 files changed, 2 insertions(+), 7 deletions(-)

--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -7,6 +7,7 @@
 #include <linux/swapops.h>
 #include <linux/kmemleak.h>
 #include <linux/sched/task.h>
+#include <linux/sched/mm.h>
 
 #include <asm/set_memory.h>
 #include <asm/e820/api.h>
@@ -790,7 +791,7 @@ 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
@@ -2424,11 +2424,6 @@ 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.