On Thu, 1 Feb 2018 10:40:30 +0100 Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Wed, Jan 31, 2018 at 04:15:51PM -0800, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> > -static inline void mmdrop(struct mm_struct *mm)
> > -{
> > - if (unlikely(atomic_dec_and_test(&mm->mm_count)))
> > - __mmdrop(mm);
> > -}
>
> I would prefer to keep that inline. Doing a CALL+RET for just the
> decrement is a bit silly methinks.
Good point. I'll let this bake for a while:
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: include/linux/sched/mm.h: re-inline mmdrop()
As Peter points out, Doing a CALL+RET for just the decrement is a bit silly.
Fixes: d70f2a14b72a4bc ("include/linux/sched/mm.h: uninline mmdrop_async(), etc")
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sched/mm.h | 8 +++++++-
kernel/fork.c | 10 ++--------
2 files changed, 9 insertions(+), 9 deletions(-)
diff -puN include/linux/sched/mm.h~a include/linux/sched/mm.h
--- a/include/linux/sched/mm.h~a
+++ a/include/linux/sched/mm.h
@@ -35,7 +35,13 @@ static inline void mmgrab(struct mm_stru
atomic_inc(&mm->mm_count);
}
-extern void mmdrop(struct mm_struct *mm);
+extern void __mmdrop(struct mm_struct *mm);
+
+static inline void mmdrop(struct mm_struct *mm)
+{
+ if (unlikely(atomic_dec_and_test(&mm->mm_count)))
+ __mmdrop(mm);
+}
/**
* mmget() - Pin the address space associated with a &struct mm_struct.
diff -puN kernel/fork.c~a kernel/fork.c
--- a/kernel/fork.c~a
+++ a/kernel/fork.c
@@ -591,7 +591,7 @@ static void check_mm(struct mm_struct *m
* is dropped: either by a lazy thread or by
* mmput. Free the page directory and the mm.
*/
-static void __mmdrop(struct mm_struct *mm)
+void __mmdrop(struct mm_struct *mm)
{
BUG_ON(mm == &init_mm);
mm_free_pgd(mm);
@@ -602,13 +602,7 @@ static void __mmdrop(struct mm_struct *m
put_user_ns(mm->user_ns);
free_mm(mm);
}
-
-void mmdrop(struct mm_struct *mm)
-{
- if (unlikely(atomic_dec_and_test(&mm->mm_count)))
- __mmdrop(mm);
-}
-EXPORT_SYMBOL_GPL(mmdrop);
+EXPORT_SYMBOL_GPL(__mmdrop);
static void mmdrop_async_fn(struct work_struct *work)
{
_
--
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