From: Wei Yang richardw.yang@linux.intel.com
mainline inclusion from mainline-v5.6-rc1 commit fac0516b5534897bf4c4a88daa06a8cfa5611b23 category: bugfix bugzilla: 47240 CVE: NA
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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: 87eaceb3faa5 ("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: Liu Shixin liushixin2@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- mm/memcontrol.c | 18 ------------------ 1 file changed, 18 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 034e546090841..88ab44a5696fd 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5240,14 +5240,6 @@ 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 @@ -5257,16 +5249,6 @@ 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;