[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, 3 deletions

diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 240143b616a2..02cf36e0331a 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -28,7 +28,6 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 	pmd_t *pmd;
 	pte_t *pte;
 
-	spin_lock(&mm->page_table_lock);
 	pgd = pgd_offset(mm, proc);
 	pud = pud_alloc(mm, pgd, proc);
 	if (!pud)
@@ -63,7 +62,6 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 	*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
 	*pte = pte_mkexec(*pte);
 	*pte = pte_wrprotect(*pte);
-	spin_unlock(&mm->page_table_lock);
 	return(0);
 
  out_pmd:
@@ -71,7 +69,6 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
  out_pte:
 	pmd_free(pmd);
  out:
-	spin_unlock(&mm->page_table_lock);
 	return(-ENOMEM);
 }