mm: simplify follow_pte{,pmd}

Merge __follow_pte_pmd, follow_pte_pmd and follow_pte into a single
follow_pte function and just pass two additional NULL arguments for the
two previous follow_pte callers.

[sfr@canb.auug.org.au: merge fix for "s390/pci: remove races against pte updates"]
  Link: https://lkml.kernel.org/r/20201111221254.7f6a3658@canb.auug.org.au

Link: https://lkml.kernel.org/r/20201029101432.47011-3-hch@lst.deSigned-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/s390/pci/pci_mmio.c

@@ -170,7 +170,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr,
 	if (!(vma->vm_flags & VM_WRITE))
 		goto out_unlock_mmap;
 
-	ret = follow_pte_pmd(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl);
+	ret = follow_pte(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl);
 	if (ret)
 		goto out_unlock_mmap;
 
@@ -311,7 +311,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr,
 	if (!(vma->vm_flags & VM_WRITE))
 		goto out_unlock_mmap;
 
-	ret = follow_pte_pmd(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl);
+	ret = follow_pte(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl);
 	if (ret)
 		goto out_unlock_mmap;
 

fs/dax.c

@@ -810,12 +810,11 @@ static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index,
 		address = pgoff_address(index, vma);
 
 		/*
-		 * Note because we provide range to follow_pte_pmd it will
-		 * call mmu_notifier_invalidate_range_start() on our behalf
-		 * before taking any lock.
+		 * Note because we provide range to follow_pte it will call
+		 * mmu_notifier_invalidate_range_start() on our behalf before
+		 * taking any lock.
 		 */
-		if (follow_pte_pmd(vma->vm_mm, address, &range,
-				   &ptep, &pmdp, &ptl))
+		if (follow_pte(vma->vm_mm, address, &range, &ptep, &pmdp, &ptl))
 			continue;
 
 		/*

include/linux/mm.h

@@ -1641,9 +1641,9 @@ void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
 		unsigned long end, unsigned long floor, unsigned long ceiling);
 int
 copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma);
-int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
-		   struct mmu_notifier_range *range,
-		   pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp);
+int follow_pte(struct mm_struct *mm, unsigned long address,
+		struct mmu_notifier_range *range, pte_t **ptepp, pmd_t **pmdpp,
+		spinlock_t **ptlp);
 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 	unsigned long *pfn);
 int follow_phys(struct vm_area_struct *vma, unsigned long address,

mm/memory.c

@@ -4707,9 +4707,9 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
 }
 #endif /* __PAGETABLE_PMD_FOLDED */
 
-static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
-			    struct mmu_notifier_range *range,
-			    pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
+int follow_pte(struct mm_struct *mm, unsigned long address,
+	       struct mmu_notifier_range *range, pte_t **ptepp, pmd_t **pmdpp,
+	       spinlock_t **ptlp)
 {
 	pgd_t *pgd;
 	p4d_t *p4d;
@@ -4774,31 +4774,6 @@ static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
 	return -EINVAL;
 }
 
-static inline int follow_pte(struct mm_struct *mm, unsigned long address,
-			     pte_t **ptepp, spinlock_t **ptlp)
-{
-	int res;
-
-	/* (void) is needed to make gcc happy */
-	(void) __cond_lock(*ptlp,
-			   !(res = __follow_pte_pmd(mm, address, NULL,
-						    ptepp, NULL, ptlp)));
-	return res;
-}
-
-int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
-		   struct mmu_notifier_range *range,
-		   pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
-{
-	int res;
-
-	/* (void) is needed to make gcc happy */
-	(void) __cond_lock(*ptlp,
-			   !(res = __follow_pte_pmd(mm, address, range,
-						    ptepp, pmdpp, ptlp)));
-	return res;
-}
-
 /**
  * follow_pfn - look up PFN at a user virtual address
  * @vma: memory mapping
@@ -4819,7 +4794,7 @@ int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 		return ret;
 
-	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
+	ret = follow_pte(vma->vm_mm, address, NULL, &ptep, NULL, &ptl);
 	if (ret)
 		return ret;
 	*pfn = pte_pfn(*ptep);
@@ -4840,7 +4815,7 @@ int follow_phys(struct vm_area_struct *vma,
 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 		goto out;
 
-	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
+	if (follow_pte(vma->vm_mm, address, NULL, &ptep, NULL, &ptl))
 		goto out;
 	pte = *ptep;