[PATCH] mm: powerpc ptlock comments

Update comments (only) on page_table_lock and mmap_sem in arch/powerpc.
Removed the comment on page_table_lock from hash_huge_page: since it's no
longer taking page_table_lock itself, it's irrelevant whether others are; but
how it is safe (even against huge file truncation?) I can't say.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/powerpc/mm/tlb_64.c b/arch/powerpc/mm/tlb_64.c
index 53e31b834ace..859d29a0cac5 100644
--- a/arch/powerpc/mm/tlb_64.c
+++ b/arch/powerpc/mm/tlb_64.c
@@ -95,7 +95,7 @@ static void pte_free_submit(struct pte_freelist_batch *batch)
 
 void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf)
 {
-        /* This is safe as we are holding page_table_lock */
+        /* This is safe since tlb_gather_mmu has disabled preemption */
         cpumask_t local_cpumask = cpumask_of_cpu(smp_processor_id());
         struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
 
@@ -206,7 +206,7 @@ void __flush_tlb_pending(struct ppc64_tlb_batch *batch)
 
 void pte_free_finish(void)
 {
-        /* This is safe as we are holding page_table_lock */
+        /* This is safe since tlb_gather_mmu has disabled preemption */
         struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
 
         if (*batchp == NULL)