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

commit 3f4c8211d982099be693be9aa7d6fc4607dff290 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 2ff4f61f1d25456e759283bbcc1f6098b1c07392..086b274fa60f65bff6e6c10b818f8601fbcf856a 100644 (file)
--- 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/cpu_device_id.h>
@@ -736,7 +737,7 @@ void __init poking_init(void)
        spinlock_t *ptl;
        pte_t *ptep;
 
-       poking_mm = copy_init_mm();
+       poking_mm = mm_alloc();
        BUG_ON(!poking_mm);
 
        /* Xen PV guests need the PGD to be pinned. */

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 6f33a07858cf6a92dfedc45f05f8437bf0d99b5e..1d012e20da6a0387beecfb9730f3c8bb290a1301 100644 (file)
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -93,7 +93,6 @@ extern long _do_fork(struct kernel_clone_args *kargs);
 extern bool legacy_clone_args_valid(const struct kernel_clone_args *kargs);
 extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
 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 *);
 

diff --git a/kernel/fork.c b/kernel/fork.c
index 5b4a19682207ab7c20a91f06d1b7d3092473f7c5..9b65c523751cc12aeef98e8a2d5fd0c1d40f3212 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2335,11 +2335,6 @@ struct task_struct *fork_idle(int cpu)
        return task;
 }
 
-struct mm_struct *copy_init_mm(void)
-{
-       return dup_mm(NULL, &init_mm);
-}
-
 /*
  *  Ok, this is the main fork-routine.
  *