[PATCH vmalloc] reduce purge_lock range and hold time of

[zhouxianrong]

From: z00281421 <z00281...@notesmail.huawei.com>

i think no need to place __free_vmap_area loop in purge_lock;
_free_vmap_area could be non-atomic operations with flushing tlb
but must be done after flush tlb. and the whole__free_vmap_area loops
also could be non-atomic operations. if so we could improve realtime
because the loop times sometimes is larg and spend a few time.

Signed-off-by: z00281421 <z00281...@notesmail.huawei.com>
---
 mm/vmalloc.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 91f44e7..9d9154d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -661,13 +661,23 @@ static void __purge_vmap_area_lazy(unsigned long *start, 
unsigned long *end,
        if (nr || force_flush)
                flush_tlb_kernel_range(*start, *end);
 
+       spin_unlock(&purge_lock);
+
        if (nr) {
+               /* the batch count should not be too small
+               ** because if vmalloc space is few free is first than alloc.
+               */
+               unsigned char batch = -1;
                spin_lock(&vmap_area_lock);
-               llist_for_each_entry_safe(va, n_va, valist, purge_list)
+               llist_for_each_entry_safe(va, n_va, valist, purge_list) {
                        __free_vmap_area(va);
+                       if (!batch--) {
+                               spin_unlock(&vmap_area_lock);
+                               spin_lock(&vmap_area_lock);
+                       }
+               }
                spin_unlock(&vmap_area_lock);
        }
-       spin_unlock(&purge_lock);
 }
 
 /*
-- 
1.7.9.5