Commit fac0516b authored Jan 30, 2020 by Wei Yang Committed by Linus Torvalds Jan 31, 2020

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: Wei Yang <richardw.yang@linux.intel.com>
Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Yang 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus 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;

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