1 files changed, 34 insertions, 30 deletions

diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index 2286c2ea60ec..39fd5df73317 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -61,32 +61,8 @@ static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address,
 	return ret;
 }
 
-#if USE_SPLIT_PTE_PTLOCKS
-/*
- * If we are using split PTE locks, then we need to take the page
- * lock here.  Otherwise we are using shared mm->page_table_lock
- * which is already locked, thus cannot take it.
- */
-static inline void do_pte_lock(spinlock_t *ptl)
-{
-	/*
-	 * Use nested version here to indicate that we are already
-	 * holding one similar spinlock.
-	 */
-	spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
-}
-
-static inline void do_pte_unlock(spinlock_t *ptl)
-{
-	spin_unlock(ptl);
-}
-#else /* !USE_SPLIT_PTE_PTLOCKS */
-static inline void do_pte_lock(spinlock_t *ptl) {}
-static inline void do_pte_unlock(spinlock_t *ptl) {}
-#endif /* USE_SPLIT_PTE_PTLOCKS */
-
 static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
-	unsigned long pfn)
+		      unsigned long pfn, bool need_lock)
 {
 	spinlock_t *ptl;
 	pgd_t *pgd;
@@ -94,6 +70,7 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
+	pmd_t pmdval;
 	int ret;
 
 	pgd = pgd_offset(vma->vm_mm, address);
@@ -112,20 +89,32 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
 	if (pmd_none_or_clear_bad(pmd))
 		return 0;
 
+again:
 	/*
 	 * This is called while another page table is mapped, so we
 	 * must use the nested version.  This also means we need to
 	 * open-code the spin-locking.
 	 */
-	pte = pte_offset_map_nolock(vma->vm_mm, pmd, address, &ptl);
+	pte = pte_offset_map_rw_nolock(vma->vm_mm, pmd, address, &pmdval, &ptl);
 	if (!pte)
 		return 0;
 
-	do_pte_lock(ptl);
+	if (need_lock) {
+		/*
+		 * Use nested version here to indicate that we are already
+		 * holding one similar spinlock.
+		 */
+		spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
+		if (unlikely(!pmd_same(pmdval, pmdp_get_lockless(pmd)))) {
+			pte_unmap_unlock(pte, ptl);
+			goto again;
+		}
+	}
 
 	ret = do_adjust_pte(vma, address, pfn, pte);
 
-	do_pte_unlock(ptl);
+	if (need_lock)
+		spin_unlock(ptl);
 	pte_unmap(pte);
 
 	return ret;
@@ -133,8 +122,10 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
 
 static void
 make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
-	unsigned long addr, pte_t *ptep, unsigned long pfn)
+	      unsigned long addr, pte_t *ptep, unsigned long pfn)
 {
+	const unsigned long pmd_start_addr = ALIGN_DOWN(addr, PMD_SIZE);
+	const unsigned long pmd_end_addr = pmd_start_addr + PMD_SIZE;
 	struct mm_struct *mm = vma->vm_mm;
 	struct vm_area_struct *mpnt;
 	unsigned long offset;
@@ -151,6 +142,14 @@ make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
 	flush_dcache_mmap_lock(mapping);
 	vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) {
 		/*
+		 * If we are using split PTE locks, then we need to take the pte
+		 * lock. Otherwise we are using shared mm->page_table_lock which
+		 * is already locked, thus cannot take it.
+		 */
+		bool need_lock = IS_ENABLED(CONFIG_SPLIT_PTE_PTLOCKS);
+		unsigned long mpnt_addr;
+
+		/*
 		 * If this VMA is not in our MM, we can ignore it.
 		 * Note that we intentionally mask out the VMA
 		 * that we are fixing up.
@@ -160,7 +159,12 @@ make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
 		if (!(mpnt->vm_flags & VM_MAYSHARE))
 			continue;
 		offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
-		aliases += adjust_pte(mpnt, mpnt->vm_start + offset, pfn);
+		mpnt_addr = mpnt->vm_start + offset;
+
+		/* Avoid deadlocks by not grabbing the same PTE lock again. */
+		if (mpnt_addr >= pmd_start_addr && mpnt_addr < pmd_end_addr)
+			need_lock = false;
+		aliases += adjust_pte(mpnt, mpnt_addr, pfn, need_lock);
 	}
 	flush_dcache_mmap_unlock(mapping);
 	if (aliases)