This is a note to let you know that I've just added the patch titled
x86/mm: Use mm_alloc() in poking_init()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-mm-use-mm_alloc-in-poking_init.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3f4c8211d982099be693be9aa7d6fc4607dff290 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Tue, 25 Oct 2022 21:38:21 +0200
Subject: x86/mm: Use mm_alloc() in poking_init()
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20221025201057.816175235@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -823,7 +823,7 @@ 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. */
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -87,7 +87,6 @@ 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
@@ -2522,11 +2522,6 @@ 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.
Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are
queue-5.15/x86-mm-fix-poking_init-for-xen-pv-guests.patch
queue-5.15/x86-mm-use-mm_alloc-in-poking_init.patch
queue-5.15/mm-move-mm_cachep-initialization-to-mm_init.patch
queue-5.15/x86-mm-initialize-text-poking-earlier.patch
