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Subject[tip: x86/mm] x86/mm: Use mm_alloc() in poking_init()
The following commit has been merged into the x86/mm branch of tip:

Commit-ID: 107b6828a7cde2de0bb293588a59892831cef78b
Gitweb: https://git.kernel.org/tip/107b6828a7cde2de0bb293588a59892831cef78b
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Tue, 25 Oct 2022 21:38:21 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 01 Nov 2022 13:43:57 +01:00

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
---
arch/x86/mm/init.c | 2 +-
include/linux/sched/task.h | 1 -
kernel/fork.c | 5 -----
3 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 9121bc1..d398735 100644
--- 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
--- 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
--- 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.
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