Now that we fixed the problem that caused the revert cd94154cc6a
("[S390] fix tlb flushing for page table pages") of the original
36409f6353fc2 ("[S390] use generic RCU page-table freeing code"), we
can revert the revert.
Original-patch-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
arch/s390/Kconfig | 1
arch/s390/include/asm/pgalloc.h | 3 +
arch/s390/include/asm/tlb.h | 22 +++++++++++++
arch/s390/mm/pgtable.c | 63 +---------------------------------------
4 files changed, 28 insertions(+), 61 deletions(-)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -84,6 +84,7 @@ 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
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -22,7 +22,10 @@ void crst_table_free(struct mm_struct *,
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)
{
--- a/arch/s390/include/asm/tlb.h
+++ b/arch/s390/include/asm/tlb.h
@@ -30,10 +30,14 @@
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;
@@ -45,6 +49,7 @@ 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,
@@ -52,20 +57,29 @@ static inline void tlb_gather_mmu(struct
{
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_table_flush(tlb);
+ tlb_flush_mmu(tlb);
}
/*
@@ -91,8 +105,10 @@ static inline void tlb_remove_page(struc
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);
}
@@ -109,8 +125,10 @@ static inline void pmd_free_tlb(struct m
#ifdef CONFIG_64BIT
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
}
@@ -128,8 +146,10 @@ static inline void pud_free_tlb(struct m
#ifdef CONFIG_64BIT
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
}
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -678,6 +678,8 @@ void page_table_free(struct mm_struct *m
}
}
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+
static void __page_table_free_rcu(void *table, unsigned bit)
{
struct page *page;
@@ -731,66 +733,7 @@ void __tlb_remove_table(void *_table)
free_pages((unsigned long) table, ALLOC_ORDER);
}
-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);
-}
+#endif
/*
* switch on pgstes for its userspace process (for kvm)
--
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