[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, 0 insertions, 14 deletions

diff --git a/arch/arm/mm/mm-armv.c b/arch/arm/mm/mm-armv.c
index 61bc2fa0511e..60f3e039bac2 100644
--- a/arch/arm/mm/mm-armv.c
+++ b/arch/arm/mm/mm-armv.c
@@ -180,11 +180,6 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
 
         if (!vectors_high()) {
                 /*
-                 * This lock is here just to satisfy pmd_alloc and pte_lock
-                 */
-                spin_lock(&mm->page_table_lock);
-
-                /*
                  * On ARM, first page must always be allocated since it
                  * contains the machine vectors.
                  */
@@ -201,23 +196,14 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
                 set_pte(new_pte, *init_pte);
                 pte_unmap_nested(init_pte);
                 pte_unmap(new_pte);
-
-                spin_unlock(&mm->page_table_lock);
         }
 
         return new_pgd;
 
 no_pte:
-        spin_unlock(&mm->page_table_lock);
         pmd_free(new_pmd);
-        free_pages((unsigned long)new_pgd, 2);
-        return NULL;
-
 no_pmd:
-        spin_unlock(&mm->page_table_lock);
         free_pages((unsigned long)new_pgd, 2);
-        return NULL;
-
 no_pgd:
         return NULL;
 }