Merge branch 'linus' into locking/core, to resolve conflicts

 Conflicts:
	include/linux/mm_types.h
	mm/huge_memory.c

I removed the smp_mb__before_spinlock() like the following commit does:

  8b1b436dd1cc ("mm, locking: Rework {set,clear,mm}_tlb_flush_pending()")

and fixed up the affected commits.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 40 insertions, 26 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 36ea3cf7d85e..dc1edec05a3f 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -487,14 +487,12 @@ struct mm_struct {
 	/* numa_scan_seq prevents two threads setting pte_numa */
 	int numa_scan_seq;
 #endif
-#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
 	/*
 	 * An operation with batched TLB flushing is going on. Anything that
 	 * can move process memory needs to flush the TLB when moving a
 	 * PROT_NONE or PROT_NUMA mapped page.
 	 */
-	bool tlb_flush_pending;
-#endif
+	atomic_t tlb_flush_pending;
 #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 	/* See flush_tlb_batched_pending() */
 	bool tlb_flush_batched;
@@ -522,12 +520,18 @@ static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
 	return mm->cpu_vm_mask_var;
 }
 
-#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
+struct mmu_gather;
+extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
+				unsigned long start, unsigned long end);
+extern void tlb_finish_mmu(struct mmu_gather *tlb,
+				unsigned long start, unsigned long end);
+
 /*
  * Memory barriers to keep this state in sync are graciously provided by
  * the page table locks, outside of which no page table modifications happen.
- * The barriers below prevent the compiler from re-ordering the instructions
- * around the memory barriers that are already present in the code.
+ * The barriers are used to ensure the order between tlb_flush_pending updates,
+ * which happen while the lock is not taken, and the PTE updates, which happen
+ * while the lock is taken, are serialized.
  */
 static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
 {
@@ -535,11 +539,26 @@ static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
 	 * Must be called with PTL held; such that our PTL acquire will have
 	 * observed the store from set_tlb_flush_pending().
 	 */
-	return mm->tlb_flush_pending;
+	return atomic_read(&mm->tlb_flush_pending) > 0;
+}
+
+/*
+ * Returns true if there are two above TLB batching threads in parallel.
+ */
+static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
+{
+	return atomic_read(&mm->tlb_flush_pending) > 1;
+}
+
+static inline void init_tlb_flush_pending(struct mm_struct *mm)
+{
+	atomic_set(&mm->tlb_flush_pending, 0);
 }
-static inline void set_tlb_flush_pending(struct mm_struct *mm)
+
+static inline void inc_tlb_flush_pending(struct mm_struct *mm)
 {
-	mm->tlb_flush_pending = true;
+	atomic_inc(&mm->tlb_flush_pending);
+
 	/*
 	 * The only time this value is relevant is when there are indeed pages
 	 * to flush. And we'll only flush pages after changing them, which
@@ -547,7 +566,7 @@ static inline void set_tlb_flush_pending(struct mm_struct *mm)
 	 *
 	 * So the ordering here is:
 	 *
-	 *	mm->tlb_flush_pending = true;
+	 *	atomic_inc(&mm->tlb_flush_pending);
 	 *	spin_lock(&ptl);
 	 *	...
 	 *	set_pte_at();
@@ -559,30 +578,25 @@ static inline void set_tlb_flush_pending(struct mm_struct *mm)
 	 *				spin_unlock(&ptl);
 	 *
 	 *	flush_tlb_range();
-	 *	mm->tlb_flush_pending = false;
+	 *	atomic_dec(&mm->tlb_flush_pending);
 	 *
 	 * So the =true store is constrained by the PTL unlock, and the =false
 	 * store is constrained by the TLB invalidate.
 	 */
 }
+
 /* Clearing is done after a TLB flush, which also provides a barrier. */
-static inline void clear_tlb_flush_pending(struct mm_struct *mm)
-{
-	/* see set_tlb_flush_pending */
-	mm->tlb_flush_pending = false;
-}
-#else
-static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
-{
-	return false;
-}
-static inline void set_tlb_flush_pending(struct mm_struct *mm)
-{
-}
-static inline void clear_tlb_flush_pending(struct mm_struct *mm)
+static inline void dec_tlb_flush_pending(struct mm_struct *mm)
 {
+	/*
+	 * Guarantee that the tlb_flush_pending does not not leak into the
+	 * critical section, since we must order the PTE change and changes to
+	 * the pending TLB flush indication. We could have relied on TLB flush
+	 * as a memory barrier, but this behavior is not clearly documented.
+	 */
+	smp_mb__before_atomic();
+	atomic_dec(&mm->tlb_flush_pending);
 }
-#endif
 
 struct vm_fault;