mm/huge_memory.c: reduce critical section protected by split_queue_lock

split_queue_lock protects data in struct deferred_split.  We can release
the lock after delete the page from deferred_split_queue.

This patch moves the THP accounting out of the lock protection, which is
introduced in commit 65c453778aea ("mm, rmap: account shmem thp pages").

Link: http://lkml.kernel.org/r/20200110025516.23996-1-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4439e91..5b28769 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2799,6 +2799,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
                        ds_queue->split_queue_len--;
                        list_del(page_deferred_list(head));
                }
+               spin_unlock(&ds_queue->split_queue_lock);
                if (mapping) {
                        if (PageSwapBacked(head))
                                __dec_node_page_state(head, NR_SHMEM_THPS);
@@ -2806,7 +2807,6 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
                                __dec_node_page_state(head, NR_FILE_THPS);
                }
 
-               spin_unlock(&ds_queue->split_queue_lock);
                __split_huge_page(page, list, end, flags);
                if (PageSwapCache(head)) {
                        swp_entry_t entry = { .val = page_private(head) };