Commit fac0516b authored by Wei Yang's avatar Wei Yang Committed by Linus Torvalds
Browse files

mm: thp: don't need care deferred split queue in memcg charge move path 

If compound is true, this means it is a PMD mapped THP.  Which implies
the page is not linked to any defer list.  So the first code chunk will
not be executed.

Also with this reason, it would not be proper to add this page to a
defer list.  So the second code chunk is not correct.

Based on this, we should remove the defer list related code.

[yang.shi@linux.alibaba.com: better patch title]
Link: http://lkml.kernel.org/r/20200117233836.3434-1-richardw.yang@linux.intel.com


Fixes: 87eaceb3 ("mm: thp: make deferred split shrinker memcg aware")
Signed-off-by: default avatarWei Yang <richardw.yang@linux.intel.com>
Suggested-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarYang Shi <yang.shi@linux.alibaba.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>    [5.4+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f1037ec0

mm/memcontrol.c

+0 −18
Original line number Diff line number Diff line
@@ -5340,14 +5340,6 @@ static int mem_cgroup_move_account(struct page *page, 
		__mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages);

	}



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	if (compound && !list_empty(page_deferred_list(page))) {

		spin_lock(&from->deferred_split_queue.split_queue_lock);

		list_del_init(page_deferred_list(page));

		from->deferred_split_queue.split_queue_len--;

		spin_unlock(&from->deferred_split_queue.split_queue_lock);

	}

#endif

	/*

	 * It is safe to change page->mem_cgroup here because the page

	 * is referenced, charged, and isolated - we can't race with
@@ -5357,16 +5349,6 @@ static int mem_cgroup_move_account(struct page *page, 
	/* caller should have done css_get */

	page->mem_cgroup = to;



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	if (compound && list_empty(page_deferred_list(page))) {

		spin_lock(&to->deferred_split_queue.split_queue_lock);

		list_add_tail(page_deferred_list(page),

			      &to->deferred_split_queue.split_queue);

		to->deferred_split_queue.split_queue_len++;

		spin_unlock(&to->deferred_split_queue.split_queue_lock);

	}

#endif



	spin_unlock_irqrestore(&from->move_lock, flags);



	ret = 0;