[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;
 }