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

commit fac0516b55 upstream.

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: 87eaceb3fa ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Wei Yang 2020-01-30 22:11:20 -08:00 committed by Greg Kroah-Hartman
parent aab4189dfd
commit 95419e7ef2
1 changed files with 0 additions and 18 deletions
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18
mm/memcontrol.c
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@ -5465,14 +5465,6 @@ 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
@ -5482,16 +5474,6 @@ 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;