[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 afc01ce..112c316 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;
 }