4 files changed, 61 insertions, 28 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 2b7c0fbe578..9015060919a 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -90,7 +90,6 @@ config S390
         select HAVE_KERNEL_XZ
         select HAVE_ARCH_MUTEX_CPU_RELAX
         select HAVE_ARCH_JUMP_LABEL if !MARCH_G5
-        select HAVE_RCU_TABLE_FREE if SMP
         select ARCH_SAVE_PAGE_KEYS if HIBERNATION
         select HAVE_MEMBLOCK
         select HAVE_MEMBLOCK_NODE_MAP
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 8eef9b5b3cf..78e3041919d 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -22,10 +22,7 @@ void crst_table_free(struct mm_struct *, unsigned long *);
 
 unsigned long *page_table_alloc(struct mm_struct *, unsigned long);
 void page_table_free(struct mm_struct *, unsigned long *);
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 void page_table_free_rcu(struct mmu_gather *, unsigned long *);
-void __tlb_remove_table(void *_table);
-#endif
 
 static inline void clear_table(unsigned long *s, unsigned long val, size_t n)
 {
diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
index c687a2c8346..775a5eea8f9 100644
--- a/arch/s390/include/asm/tlb.h
+++ b/arch/s390/include/asm/tlb.h
@@ -30,14 +30,10 @@
 
 struct mmu_gather {
         struct mm_struct *mm;
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
         struct mmu_table_batch *batch;
-#endif
         unsigned int fullmm;
-        unsigned int need_flush;
 };
 
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 struct mmu_table_batch {
         struct rcu_head         rcu;
         unsigned int            nr;
@@ -49,7 +45,6 @@ struct mmu_table_batch {
 
 extern void tlb_table_flush(struct mmu_gather *tlb);
 extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
-#endif
 
 static inline void tlb_gather_mmu(struct mmu_gather *tlb,
                                   struct mm_struct *mm,
@@ -57,29 +52,20 @@ static inline void tlb_gather_mmu(struct mmu_gather *tlb,
 {
         tlb->mm = mm;
         tlb->fullmm = full_mm_flush;
-        tlb->need_flush = 0;
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
         tlb->batch = NULL;
-#endif
         if (tlb->fullmm)
                 __tlb_flush_mm(mm);
 }
 
 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
 {
-        if (!tlb->need_flush)
-                return;
-        tlb->need_flush = 0;
-        __tlb_flush_mm(tlb->mm);
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
         tlb_table_flush(tlb);
-#endif
 }
 
 static inline void tlb_finish_mmu(struct mmu_gather *tlb,
                                   unsigned long start, unsigned long end)
 {
-        tlb_flush_mmu(tlb);
+        tlb_table_flush(tlb);
 }
 
 /*
@@ -105,10 +91,8 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
                                 unsigned long address)
 {
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
         if (!tlb->fullmm)
                 return page_table_free_rcu(tlb, (unsigned long *) pte);
-#endif
         page_table_free(tlb->mm, (unsigned long *) pte);
 }
 
@@ -125,10 +109,8 @@ static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
 #ifdef __s390x__
         if (tlb->mm->context.asce_limit <= (1UL << 31))
                 return;
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
         if (!tlb->fullmm)
                 return tlb_remove_table(tlb, pmd);
-#endif
         crst_table_free(tlb->mm, (unsigned long *) pmd);
 #endif
 }
@@ -146,10 +128,8 @@ static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
 #ifdef __s390x__
         if (tlb->mm->context.asce_limit <= (1UL << 42))
                 return;
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
         if (!tlb->fullmm)
                 return tlb_remove_table(tlb, pud);
-#endif
         crst_table_free(tlb->mm, (unsigned long *) pud);
 #endif
 }
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 373adf69b01..6e765bf0067 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -678,8 +678,6 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
         }
 }
 
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
-
 static void __page_table_free_rcu(void *table, unsigned bit)
 {
         struct page *page;
@@ -733,7 +731,66 @@ void __tlb_remove_table(void *_table)
                 free_pages((unsigned long) table, ALLOC_ORDER);
 }
 
-#endif
+static void tlb_remove_table_smp_sync(void *arg)
+{
+        /* Simply deliver the interrupt */
+}
+
+static void tlb_remove_table_one(void *table)
+{
+        /*
+         * This isn't an RCU grace period and hence the page-tables cannot be
+         * assumed to be actually RCU-freed.
+         *
+         * It is however sufficient for software page-table walkers that rely
+         * on IRQ disabling. See the comment near struct mmu_table_batch.
+         */
+        smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
+        __tlb_remove_table(table);
+}
+
+static void tlb_remove_table_rcu(struct rcu_head *head)
+{
+        struct mmu_table_batch *batch;
+        int i;
+
+        batch = container_of(head, struct mmu_table_batch, rcu);
+
+        for (i = 0; i < batch->nr; i++)
+                __tlb_remove_table(batch->tables[i]);
+
+        free_page((unsigned long)batch);
+}
+
+void tlb_table_flush(struct mmu_gather *tlb)
+{
+        struct mmu_table_batch **batch = &tlb->batch;
+
+        if (*batch) {
+                __tlb_flush_mm(tlb->mm);
+                call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
+                *batch = NULL;
+        }
+}
+
+void tlb_remove_table(struct mmu_gather *tlb, void *table)
+{
+        struct mmu_table_batch **batch = &tlb->batch;
+
+        if (*batch == NULL) {
+                *batch = (struct mmu_table_batch *)
+                        __get_free_page(GFP_NOWAIT | __GFP_NOWARN);
+                if (*batch == NULL) {
+                        __tlb_flush_mm(tlb->mm);
+                        tlb_remove_table_one(table);
+                        return;
+                }
+                (*batch)->nr = 0;
+        }
+        (*batch)->tables[(*batch)->nr++] = table;
+        if ((*batch)->nr == MAX_TABLE_BATCH)
+                tlb_table_flush(tlb);
+}
 
 /*
  * switch on pgstes for its userspace process (for kvm)