sparc/mm: avoid calling arch_enter/leave_lazy_mmu() in set_ptes

commit eb61ad1 upstream.

With commit 1a10a44 ("sparc64: implement the new page table range
API") set_ptes was added to the sparc architecture.  The implementation
included calling arch_enter/leave_lazy_mmu() calls.

The patch removes the usage of arch_enter/leave_lazy_mmu() since this
implies nesting of lazy mmu regions which is not supported.  Without this
fix, lazy mmu mode is effectively disabled because we exit the mode after
the first set_ptes:

remap_pte_range()
  -> arch_enter_lazy_mmu()
  -> set_ptes()
      -> arch_enter_lazy_mmu()
      -> arch_leave_lazy_mmu()
  -> arch_leave_lazy_mmu()

Powerpc suffered the same problem and fixed it in a corresponding way with
commit 47b8def ("powerpc/mm: Avoid calling
arch_enter/leave_lazy_mmu() in set_ptes").

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 1a10a44 ("sparc64: implement the new page table range API")
Signed-off-by: Ryan Roberts <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Acked-by: Andreas Larsson <[email protected]>
Acked-by: Juergen Gross <[email protected]>
Cc: Borislav Betkov <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Juegren Gross <[email protected]>
Cc: Matthew Wilcow (Oracle) <[email protected]>
Cc: Thomas Gleinxer <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: ryanhrob

arch/sparc/include/asm/pgtable_64.h

@@ -936,7 +936,6 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
 		pte_t *ptep, pte_t pte, unsigned int nr)
 {
-	arch_enter_lazy_mmu_mode();
 	for (;;) {
 		__set_pte_at(mm, addr, ptep, pte, 0);
 		if (--nr == 0)
@@ -945,7 +944,6 @@ static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
 		pte_val(pte) += PAGE_SIZE;
 		addr += PAGE_SIZE;
 	}
-	arch_leave_lazy_mmu_mode();
 }
 #define set_ptes set_ptes