[PATCH] mm: arches skip ptlock

Convert those few architectures which are calling pud_alloc, pmd_alloc,
pte_alloc_map on a user mm, not to take the page_table_lock first, nor drop it
after.  Each of these can continue to use pte_alloc_map, no need to change
over to pte_alloc_map_lock, they're neither racy nor swappable.

In the sparc64 io_remap_pfn_range, flush_tlb_range then falls outside of the
page_table_lock: that's okay, on sparc64 it's like flush_tlb_mm, and that has
always been called from outside of page_table_lock in dup_mmap.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/arch/sparc64/mm/generic.c b/arch/sparc64/mm/generic.c
index afc01cec701f..112c316e7cd2 100644
--- a/arch/sparc64/mm/generic.c
+++ b/arch/sparc64/mm/generic.c
@@ -135,9 +135,8 @@ int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
         dir = pgd_offset(mm, from);
         flush_cache_range(vma, beg, end);
 
-        spin_lock(&mm->page_table_lock);
         while (from < end) {
-                pud_t *pud = pud_alloc(current->mm, dir, from);
+                pud_t *pud = pud_alloc(mm, dir, from);
                 error = -ENOMEM;
                 if (!pud)
                         break;
@@ -147,8 +146,7 @@ int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
                 from = (from + PGDIR_SIZE) & PGDIR_MASK;
                 dir++;
         }
-        flush_tlb_range(vma, beg, end);
-        spin_unlock(&mm->page_table_lock);
 
+        flush_tlb_range(vma, beg, end);
         return error;
 }