mm: remove the page size change check in tlb_remove_page

Now that we check for page size change early in the loop, we can
partially revert e9d55e1570 ("mm: change the interface for
__tlb_remove_page").

This simplies the code much, by removing the need to track the last
address with which we adjusted the range.  We also go back to the older
way of filling the mmu_gather array, ie, we add an entry and then check
whether the gather batch is full.

Link: http://lkml.kernel.org/r/20161026084839.27299-6-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm/include/asm/tlb.h

@@ -213,18 +213,17 @@ tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 
 static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
+	tlb->pages[tlb->nr++] = page;
+	VM_WARN_ON(tlb->nr > tlb->max);
 	if (tlb->nr == tlb->max)
 		return true;
-	tlb->pages[tlb->nr++] = page;
 	return false;
 }
 
 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
-	if (__tlb_remove_page(tlb, page)) {
+	if (__tlb_remove_page(tlb, page))
 		tlb_flush_mmu(tlb);
-		__tlb_remove_page(tlb, page);
-	}
 }
 
 static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
@@ -233,12 +232,6 @@ static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
 	return __tlb_remove_page(tlb, page);
 }
 
-static inline bool __tlb_remove_pte_page(struct mmu_gather *tlb,
-					 struct page *page)
-{
-	return __tlb_remove_page(tlb, page);
-}
-
 static inline void tlb_remove_page_size(struct mmu_gather *tlb,
 					struct page *page, int page_size)
 {

arch/ia64/include/asm/tlb.h

@@ -207,15 +207,15 @@ tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
  */
 static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
-	if (tlb->nr == tlb->max)
-		return true;
-
 	tlb->need_flush = 1;
 
 	if (!tlb->nr && tlb->pages == tlb->local)
 		__tlb_alloc_page(tlb);
 
 	tlb->pages[tlb->nr++] = page;
+	VM_WARN_ON(tlb->nr > tlb->max);
+	if (tlb->nr == tlb->max)
+		return true;
 	return false;
 }
 
@@ -236,10 +236,8 @@ static inline void tlb_flush_mmu(struct mmu_gather *tlb)
 
 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
-	if (__tlb_remove_page(tlb, page)) {
+	if (__tlb_remove_page(tlb, page))
 		tlb_flush_mmu(tlb);
-		__tlb_remove_page(tlb, page);
-	}
 }
 
 static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
@@ -248,12 +246,6 @@ static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
 	return __tlb_remove_page(tlb, page);
 }
 
-static inline bool __tlb_remove_pte_page(struct mmu_gather *tlb,
-					 struct page *page)
-{
-	return __tlb_remove_page(tlb, page);
-}
-
 static inline void tlb_remove_page_size(struct mmu_gather *tlb,
 					struct page *page, int page_size)
 {

arch/s390/include/asm/tlb.h

@@ -104,12 +104,6 @@ static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
 	return __tlb_remove_page(tlb, page);
 }
 
-static inline bool __tlb_remove_pte_page(struct mmu_gather *tlb,
-					 struct page *page)
-{
-	return __tlb_remove_page(tlb, page);
-}
-
 static inline void tlb_remove_page_size(struct mmu_gather *tlb,
 					struct page *page, int page_size)
 {

arch/sh/include/asm/tlb.h

@@ -118,12 +118,6 @@ static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
 	return __tlb_remove_page(tlb, page);
 }
 
-static inline bool __tlb_remove_pte_page(struct mmu_gather *tlb,
-					 struct page *page)
-{
-	return __tlb_remove_page(tlb, page);
-}
-
 static inline void tlb_remove_page_size(struct mmu_gather *tlb,
 					struct page *page, int page_size)
 {

arch/um/include/asm/tlb.h

@@ -116,12 +116,6 @@ static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
 	return __tlb_remove_page(tlb, page);
 }
 
-static inline bool __tlb_remove_pte_page(struct mmu_gather *tlb,
-					 struct page *page)
-{
-	return __tlb_remove_page(tlb, page);
-}
-
 static inline void tlb_remove_page_size(struct mmu_gather *tlb,
 					struct page *page, int page_size)
 {

include/asm-generic/tlb.h

@@ -107,11 +107,6 @@ struct mmu_gather {
 	struct mmu_gather_batch	local;
 	struct page		*__pages[MMU_GATHER_BUNDLE];
 	unsigned int		batch_count;
-	/*
-	 * __tlb_adjust_range  will track the new addr here,
-	 * that that we can adjust the range after the flush
-	 */
-	unsigned long addr;
 	int page_size;
 };
 
@@ -130,12 +125,6 @@ static inline void __tlb_adjust_range(struct mmu_gather *tlb,
 {
 	tlb->start = min(tlb->start, address);
 	tlb->end = max(tlb->end, address + range_size);
-	/*
-	 * Track the last address with which we adjusted the range. This
-	 * will be used later to adjust again after a mmu_flush due to
-	 * failed __tlb_remove_page
-	 */
-	tlb->addr = address;
 }
 
 static inline void __tlb_reset_range(struct mmu_gather *tlb)
@@ -151,15 +140,11 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
 static inline void tlb_remove_page_size(struct mmu_gather *tlb,
 					struct page *page, int page_size)
 {
-	if (__tlb_remove_page_size(tlb, page, page_size)) {
+	if (__tlb_remove_page_size(tlb, page, page_size))
 		tlb_flush_mmu(tlb);
-		tlb->page_size = page_size;
-		__tlb_adjust_range(tlb, tlb->addr, page_size);
-		__tlb_remove_page_size(tlb, page, page_size);
-	}
 }
 
-static bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
 	return __tlb_remove_page_size(tlb, page, PAGE_SIZE);
 }
@@ -173,15 +158,6 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 	return tlb_remove_page_size(tlb, page, PAGE_SIZE);
 }
 
-static inline bool __tlb_remove_pte_page(struct mmu_gather *tlb, struct page *page)
-{
-	/* active->nr should be zero when we call this */
-	VM_BUG_ON_PAGE(tlb->active->nr, page);
-	tlb->page_size = PAGE_SIZE;
-	__tlb_adjust_range(tlb, tlb->addr, PAGE_SIZE);
-	return __tlb_remove_page(tlb, page);
-}
-
 #ifndef tlb_remove_check_page_size_change
 #define tlb_remove_check_page_size_change tlb_remove_check_page_size_change
 static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,

mm/memory.c

@@ -300,15 +300,14 @@ bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_
 	struct mmu_gather_batch *batch;
 
 	VM_BUG_ON(!tlb->end);
-
-	if (!tlb->page_size)
-		tlb->page_size = page_size;
-	else {
-		if (page_size != tlb->page_size)
-			return true;
-	}
+	VM_WARN_ON(tlb->page_size != page_size);
 
 	batch = tlb->active;
+	/*
+	 * Add the page and check if we are full. If so
+	 * force a flush.
+	 */
+	batch->pages[batch->nr++] = page;
 	if (batch->nr == batch->max) {
 		if (!tlb_next_batch(tlb))
 			return true;
@@ -316,7 +315,6 @@ bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_
 	}
 	VM_BUG_ON_PAGE(batch->nr > batch->max, page);
 
-	batch->pages[batch->nr++] = page;
 	return false;
 }
 
@@ -1122,7 +1120,6 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	pte_t *start_pte;
 	pte_t *pte;
 	swp_entry_t entry;
-	struct page *pending_page = NULL;
 
 	tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
 again:
@@ -1177,7 +1174,6 @@ again:
 				print_bad_pte(vma, addr, ptent, page);
 			if (unlikely(__tlb_remove_page(tlb, page))) {
 				force_flush = 1;
-				pending_page = page;
 				addr += PAGE_SIZE;
 				break;
 			}
@@ -1218,11 +1214,6 @@ again:
 	if (force_flush) {
 		force_flush = 0;
 		tlb_flush_mmu_free(tlb);
-		if (pending_page) {
-			/* remove the page with new size */
-			__tlb_remove_pte_page(tlb, pending_page);
-			pending_page = NULL;
-		}
 		if (addr != end)
 			goto again;
 	}