kernel/arm64-revert-tlb-rcu_table_free.patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1b8e973..31042fe 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -65,7 +65,6 @@ config ARM64
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
-	select HAVE_RCU_TABLE_FREE
 	select HAVE_SYSCALL_TRACEPOINTS
 	select IRQ_DOMAIN
 	select MODULES_USE_ELF_RELA
@@ -119,9 +118,6 @@ config GENERIC_CALIBRATE_DELAY
 config ZONE_DMA
 	def_bool y
 
-config HAVE_GENERIC_RCU_GUP
-	def_bool y
-
 config ARCH_DMA_ADDR_T_64BIT
 	def_bool y
 
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 800ec0e..e2e79ac 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -243,16 +243,6 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 
 #define __HAVE_ARCH_PTE_SPECIAL
 
-static inline pte_t pud_pte(pud_t pud)
-{
-	return __pte(pud_val(pud));
-}
-
-static inline pmd_t pud_pmd(pud_t pud)
-{
-	return __pmd(pud_val(pud));
-}
-
 static inline pte_t pmd_pte(pmd_t pmd)
 {
 	return __pte(pmd_val(pmd));
@@ -275,13 +265,7 @@ static inline pgprot_t mk_sect_prot(pgprot_t prot)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 #define pmd_trans_huge(pmd)	(pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
 #define pmd_trans_splitting(pmd)	pte_special(pmd_pte(pmd))
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
-#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
-struct vm_area_struct;
-void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
-			  pmd_t *pmdp);
-#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
 
 #define pmd_dirty(pmd)		pte_dirty(pmd_pte(pmd))
 #define pmd_young(pmd)		pte_young(pmd_pte(pmd))
@@ -302,7 +286,7 @@ void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
 #define pfn_pmd(pfn,prot)	(__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
 #define mk_pmd(page,prot)	pfn_pmd(page_to_pfn(page),prot)
 
-#define pud_write(pud)		pte_write(pud_pte(pud))
+#define pmd_page(pmd)           pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
 #define pud_pfn(pud)		(((pud_val(pud) & PUD_MASK) & PHYS_MASK) >> PAGE_SHIFT)
 
 #define set_pmd_at(mm, addr, pmdp, pmd)	set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd))
@@ -407,8 +391,6 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
 	return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr);
 }
 
-#define pud_page(pud)		pfn_to_page(__phys_to_pfn(pud_val(pud) & PHYS_MASK))
-
 #endif	/* CONFIG_ARM64_PGTABLE_LEVELS > 2 */
 
 #if CONFIG_ARM64_PGTABLE_LEVELS > 3
@@ -443,8 +425,6 @@ static inline pud_t *pud_offset(pgd_t *pgd, unsigned long addr)
 	return (pud_t *)pgd_page_vaddr(*pgd) + pud_index(addr);
 }
 
-#define pgd_page(pgd)		pfn_to_page(__phys_to_pfn(pgd_val(pgd) & PHYS_MASK))
-
 #endif  /* CONFIG_ARM64_PGTABLE_LEVELS > 3 */
 
 #define pgd_ERROR(pgd)		__pgd_error(__FILE__, __LINE__, pgd_val(pgd))
diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index c028fe3..62731ef 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -19,44 +19,84 @@
 #ifndef __ASM_TLB_H
 #define __ASM_TLB_H
 
-#include <linux/pagemap.h>
-#include <linux/swap.h>
-
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
-
-#define tlb_remove_entry(tlb, entry)	tlb_remove_table(tlb, entry)
-static inline void __tlb_remove_table(void *_table)
-{
-	free_page_and_swap_cache((struct page *)_table);
-}
-#else
-#define tlb_remove_entry(tlb, entry)	tlb_remove_page(tlb, entry)
-#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
+#define  __tlb_remove_pmd_tlb_entry __tlb_remove_pmd_tlb_entry
 
 #include <asm-generic/tlb.h>
 
+/*
+ * There's three ways the TLB shootdown code is used:
+ *  1. Unmapping a range of vmas.  See zap_page_range(), unmap_region().
+ *     tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
+ *  2. Unmapping all vmas.  See exit_mmap().
+ *     tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
+ *     Page tables will be freed.
+ *  3. Unmapping argument pages.  See shift_arg_pages().
+ *     tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
+ */
 static inline void tlb_flush(struct mmu_gather *tlb)
 {
 	if (tlb->fullmm) {
 		flush_tlb_mm(tlb->mm);
-	} else {
+	} else if (tlb->end > 0) {
 		struct vm_area_struct vma = { .vm_mm = tlb->mm, };
 		flush_tlb_range(&vma, tlb->start, tlb->end);
+		tlb->start = TASK_SIZE;
+		tlb->end = 0;
+	}
+}
+
+static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
+{
+	if (!tlb->fullmm) {
+		tlb->start = min(tlb->start, addr);
+		tlb->end = max(tlb->end, addr + PAGE_SIZE);
 	}
 }
 
+/*
+ * Memorize the range for the TLB flush.
+ */
+static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,
+					  unsigned long addr)
+{
+	tlb_add_flush(tlb, addr);
+}
+
+/*
+ * In the case of tlb vma handling, we can optimise these away in the
+ * case where we're doing a full MM flush.  When we're doing a munmap,
+ * the vmas are adjusted to only cover the region to be torn down.
+ */
+static inline void tlb_start_vma(struct mmu_gather *tlb,
+				 struct vm_area_struct *vma)
+{
+	if (!tlb->fullmm) {
+		tlb->start = TASK_SIZE;
+		tlb->end = 0;
+	}
+}
+
+static inline void tlb_end_vma(struct mmu_gather *tlb,
+			       struct vm_area_struct *vma)
+{
+	if (!tlb->fullmm)
+		tlb_flush(tlb);
+}
+
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
 				  unsigned long addr)
 {
 	pgtable_page_dtor(pte);
-	tlb_remove_entry(tlb, pte);
+	tlb_add_flush(tlb, addr);
+	tlb_remove_page(tlb, pte);
 }
 
 #if CONFIG_ARM64_PGTABLE_LEVELS > 2
 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
 				  unsigned long addr)
 {
-	tlb_remove_entry(tlb, virt_to_page(pmdp));
+	tlb_add_flush(tlb, addr);
+	tlb_remove_page(tlb, virt_to_page(pmdp));
 }
 #endif
 
@@ -64,8 +104,15 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
 static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pudp,
 				  unsigned long addr)
 {
-	tlb_remove_entry(tlb, virt_to_page(pudp));
+	tlb_add_flush(tlb, addr);
+	tlb_remove_page(tlb, virt_to_page(pudp));
 }
 #endif
 
+static inline void __tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp,
+						unsigned long address)
+{
+	tlb_add_flush(tlb, address);
+}
+
 #endif
diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
index b6f14e8..0d64089 100644
--- a/arch/arm64/mm/flush.c
+++ b/arch/arm64/mm/flush.c
@@ -104,19 +104,3 @@ EXPORT_SYMBOL(flush_dcache_page);
  */
 EXPORT_SYMBOL(flush_cache_all);
 EXPORT_SYMBOL(flush_icache_range);
-
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
-void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
-			  pmd_t *pmdp)
-{
-	pmd_t pmd = pmd_mksplitting(*pmdp);
-
-	VM_BUG_ON(address & ~PMD_MASK);
-	set_pmd_at(vma->vm_mm, address, pmdp, pmd);
-
-	/* dummy IPI to serialise against fast_gup */
-	kick_all_cpus_sync();
-}
-#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index db284bf..5672d7e 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -96,9 +96,10 @@ struct mmu_gather {
 #endif
 	unsigned long		start;
 	unsigned long		end;
+	unsigned int		need_flush : 1,	/* Did free PTEs */
 	/* we are in the middle of an operation to clear
 	 * a full mm and can make some optimizations */
-	unsigned int		fullmm : 1,
+				fullmm : 1,
 	/* we have performed an operation which
 	 * requires a complete flush of the tlb */
 				need_flush_all : 1;
@@ -127,58 +128,16 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 		tlb_flush_mmu(tlb);
 }
 
-static inline void __tlb_adjust_range(struct mmu_gather *tlb,
-				      unsigned long address)
-{
-	tlb->start = min(tlb->start, address);
-	tlb->end = max(tlb->end, address + PAGE_SIZE);
-}
-
-static inline void __tlb_reset_range(struct mmu_gather *tlb)
-{
-	if (tlb->fullmm) {
-		tlb->start = tlb->end = ~0;
-	} else {
-		tlb->start = TASK_SIZE;
-		tlb->end = 0;
-	}
-}
-
-/*
- * In the case of tlb vma handling, we can optimise these away in the
- * case where we're doing a full MM flush.  When we're doing a munmap,
- * the vmas are adjusted to only cover the region to be torn down.
- */
-#ifndef tlb_start_vma
-#define tlb_start_vma(tlb, vma) do { } while (0)
-#endif
-
-#define __tlb_end_vma(tlb, vma)					\
-	do {							\
-		if (!tlb->fullmm && tlb->end) {			\
-			tlb_flush(tlb);				\
-			__tlb_reset_range(tlb);			\
-		}						\
-	} while (0)
-
-#ifndef tlb_end_vma
-#define tlb_end_vma	__tlb_end_vma
-#endif
-
-#ifndef __tlb_remove_tlb_entry
-#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)
-#endif
-
 /**
  * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
  *
- * Record the fact that pte's were really unmapped by updating the range,
- * so we can later optimise away the tlb invalidate.   This helps when
- * userspace is unmapping already-unmapped pages, which happens quite a lot.
+ * Record the fact that pte's were really umapped in ->need_flush, so we can
+ * later optimise away the tlb invalidate.   This helps when userspace is
+ * unmapping already-unmapped pages, which happens quite a lot.
  */
 #define tlb_remove_tlb_entry(tlb, ptep, address)		\
 	do {							\
-		__tlb_adjust_range(tlb, address);		\
+		tlb->need_flush = 1;				\
 		__tlb_remove_tlb_entry(tlb, ptep, address);	\
 	} while (0)
 
@@ -192,27 +151,27 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
 
 #define tlb_remove_pmd_tlb_entry(tlb, pmdp, address)		\
 	do {							\
-		__tlb_adjust_range(tlb, address);		\
+		tlb->need_flush = 1;				\
 		__tlb_remove_pmd_tlb_entry(tlb, pmdp, address);	\
 	} while (0)
 
 #define pte_free_tlb(tlb, ptep, address)			\
 	do {							\
-		__tlb_adjust_range(tlb, address);		\
+		tlb->need_flush = 1;				\
 		__pte_free_tlb(tlb, ptep, address);		\
 	} while (0)
 
 #ifndef __ARCH_HAS_4LEVEL_HACK
 #define pud_free_tlb(tlb, pudp, address)			\
 	do {							\
-		__tlb_adjust_range(tlb, address);		\
+		tlb->need_flush = 1;				\
 		__pud_free_tlb(tlb, pudp, address);		\
 	} while (0)
 #endif
 
 #define pmd_free_tlb(tlb, pmdp, address)			\
 	do {							\
-		__tlb_adjust_range(tlb, address);		\
+		tlb->need_flush = 1;				\
 		__pmd_free_tlb(tlb, pmdp, address);		\
 	} while (0)
 
diff --git a/mm/memory.c b/mm/memory.c
index 411144f..2772d7a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -220,6 +220,9 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
 	/* Is it from 0 to ~0? */
 	tlb->fullmm     = !(start | (end+1));
 	tlb->need_flush_all = 0;
+	tlb->start	= start;
+	tlb->end	= end;
+	tlb->need_flush = 0;
 	tlb->local.next = NULL;
 	tlb->local.nr   = 0;
 	tlb->local.max  = ARRAY_SIZE(tlb->__pages);
@@ -229,28 +232,23 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
 	tlb->batch = NULL;
 #endif
-
-	__tlb_reset_range(tlb);
 }
 
 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
 {
-	if (!tlb->end)
-		return;
-
+	tlb->need_flush = 0;
 	tlb_flush(tlb);
 	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
 	tlb_table_flush(tlb);
 #endif
-	__tlb_reset_range(tlb);
 }
 
 static void tlb_flush_mmu_free(struct mmu_gather *tlb)
 {
 	struct mmu_gather_batch *batch;
 
-	for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
+	for (batch = &tlb->local; batch; batch = batch->next) {
 		free_pages_and_swap_cache(batch->pages, batch->nr);
 		batch->nr = 0;
 	}
@@ -259,6 +257,8 @@ static void tlb_flush_mmu_free(struct mmu_gather *tlb)
 
 void tlb_flush_mmu(struct mmu_gather *tlb)
 {
+	if (!tlb->need_flush)
+		return;
 	tlb_flush_mmu_tlbonly(tlb);
 	tlb_flush_mmu_free(tlb);
 }
@@ -293,7 +293,7 @@ int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
 	struct mmu_gather_batch *batch;
 
-	VM_BUG_ON(!tlb->end);
+	VM_BUG_ON(!tlb->need_flush);
 
 	batch = tlb->active;
 	batch->pages[batch->nr++] = page;
@@ -360,6 +360,8 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
 {
 	struct mmu_table_batch **batch = &tlb->batch;
 
+	tlb->need_flush = 1;
+
 	/*
 	 * When there's less then two users of this mm there cannot be a
 	 * concurrent page-table walk.
@@ -1161,8 +1163,20 @@ again:
 	arch_leave_lazy_mmu_mode();
 
 	/* Do the actual TLB flush before dropping ptl */
-	if (force_flush)
+	if (force_flush) {
+		unsigned long old_end;
+
+		/*
+		 * Flush the TLB just for the previous segment,
+		 * then update the range to be the remaining
+		 * TLB range.
+		 */
+		old_end = tlb->end;
+		tlb->end = addr;
 		tlb_flush_mmu_tlbonly(tlb);
+		tlb->start = addr;
+		tlb->end = old_end;
+	}
 	pte_unmap_unlock(start_pte, ptl);
 
 	/*