[rt] Refresh "sched: Move mmdrop to RCU on RT" for context changes in 4.19.129

debian/changelog

@@ -727,6 +727,8 @@ linux (4.19.129-1) UNRELEASED; urgency=medium
   * [rt] Update to 4.19.120-rt52
   * [rt] Update to 4.19.124-rt53
   * [rt] Update to 4.19.127-rt55
+  * [rt] Refresh "sched: Move mmdrop to RCU on RT" for context changes in
+    4.19.129
 
  -- Salvatore Bonaccorso <carnil@debian.org>  Wed, 13 May 2020 17:44:43 +0200
 

debian/patches-rt/0107-sched-Move-mmdrop-to-RCU-on-RT.patch

@@ -18,8 +18,6 @@ Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  kernel/sched/core.c      | 18 ++++++++++++++++--
  4 files changed, 44 insertions(+), 2 deletions(-)
 
-diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
-index 3a9a996af229..202b736ccbfa 100644
 --- a/include/linux/mm_types.h
 +++ b/include/linux/mm_types.h
 @@ -12,6 +12,7 @@
@@ -30,7 +28,7 @@ index 3a9a996af229..202b736ccbfa 100644
  #include <linux/page-flags-layout.h>
  #include <linux/workqueue.h>
  
-@@ -487,6 +488,9 @@ struct mm_struct {
+@@ -489,6 +490,9 @@
  		bool tlb_flush_batched;
  #endif
  		struct uprobes_state uprobes_state;
@@ -40,13 +38,11 @@ index 3a9a996af229..202b736ccbfa 100644
  #ifdef CONFIG_HUGETLB_PAGE
  		atomic_long_t hugetlb_usage;
  #endif
-diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
-index e9d4e389aed9..fb59f96fdd2e 100644
 --- a/include/linux/sched/mm.h
 +++ b/include/linux/sched/mm.h
-@@ -49,6 +49,17 @@ static inline void mmdrop(struct mm_struct *mm)
- 		__mmdrop(mm);
- }
+@@ -51,6 +51,17 @@
+ 
+ void mmdrop(struct mm_struct *mm);
  
 +#ifdef CONFIG_PREEMPT_RT_BASE
 +extern void __mmdrop_delayed(struct rcu_head *rhp);
@@ -62,11 +58,9 @@ index e9d4e389aed9..fb59f96fdd2e 100644
  /*
   * This has to be called after a get_task_mm()/mmget_not_zero()
   * followed by taking the mmap_sem for writing before modifying the
-diff --git a/kernel/fork.c b/kernel/fork.c
-index 309f4a20d4ac..d4ec53c72577 100644
 --- a/kernel/fork.c
 +++ b/kernel/fork.c
-@@ -642,6 +642,19 @@ void __mmdrop(struct mm_struct *mm)
+@@ -647,6 +647,19 @@
  }
  EXPORT_SYMBOL_GPL(__mmdrop);
  
@@ -86,11 +80,9 @@ index 309f4a20d4ac..d4ec53c72577 100644
  static void mmdrop_async_fn(struct work_struct *work)
  {
  	struct mm_struct *mm;
-diff --git a/kernel/sched/core.c b/kernel/sched/core.c
-index 5c23d1272429..cb89c90513dd 100644
 --- a/kernel/sched/core.c
 +++ b/kernel/sched/core.c
-@@ -2729,9 +2729,13 @@ static struct rq *finish_task_switch(struct task_struct *prev)
+@@ -2729,9 +2729,13 @@
  	 *   provided by mmdrop(),
  	 * - a sync_core for SYNC_CORE.
  	 */
@@ -105,7 +97,7 @@ index 5c23d1272429..cb89c90513dd 100644
  	}
  	if (unlikely(prev_state == TASK_DEAD)) {
  		if (prev->sched_class->task_dead)
-@@ -5601,6 +5605,8 @@ void sched_setnuma(struct task_struct *p, int nid)
+@@ -5602,6 +5606,8 @@
  #endif /* CONFIG_NUMA_BALANCING */
  
  #ifdef CONFIG_HOTPLUG_CPU
@@ -114,20 +106,19 @@ index 5c23d1272429..cb89c90513dd 100644
  /*
   * Ensure that the idle task is using init_mm right before its CPU goes
   * offline.
-@@ -5616,7 +5622,11 @@ void idle_task_exit(void)
- 		current->active_mm = &init_mm;
+@@ -5617,6 +5623,11 @@
+ 		switch_mm(mm, &init_mm, current);
  		finish_arch_post_lock_switch();
  	}
--	mmdrop(mm);
 +	/*
 +	 * Defer the cleanup to an alive cpu. On RT we can neither
 +	 * call mmdrop() nor mmdrop_delayed() from here.
 +	 */
 +	per_cpu(idle_last_mm, smp_processor_id()) = mm;
- }
  
- /*
-@@ -5928,6 +5938,10 @@ int sched_cpu_dying(unsigned int cpu)
+ 	/* finish_cpu(), as ran on the BP, will clean up the active_mm state */
+ }
+@@ -5930,6 +5941,10 @@
  	update_max_interval();
  	nohz_balance_exit_idle(rq);
  	hrtick_clear(rq);
@@ -138,6 +129,3 @@ index 5c23d1272429..cb89c90513dd 100644
  	return 0;
  }
  #endif
--- 
-2.17.1
-