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From:   Chen Huang <chenhuang5@huawei.com>
To:     Roman Gushchin <guro@fb.com>,
        Muchun Song <songmuchun@bytedance.com>,
        "Wang Hai" <wanghai38@huawei.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC:     <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        <stable@vger.kernel.org>, Chen Huang <chenhuang5@huawei.com>,
        Michal Hocko <mhocko@kernel.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        "Xiongchun Duan" <duanxiongchun@bytedance.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 5.10.y 06/11] mm: memcontrol: directly access page->memcg_data in mm/page_alloc.c
Date:   Mon, 16 Aug 2021 07:21:42 +0000
Message-ID: <20210816072147.3481782-7-chenhuang5@huawei.com>
In-Reply-To: <20210816072147.3481782-1-chenhuang5@huawei.com>
References: <20210816072147.3481782-1-chenhuang5@huawei.com>
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From: Muchun Song <songmuchun@bytedance.com>

page_memcg() is not suitable for use by page_expected_state() and
page_bad_reason().  Because it can BUG_ON() for the slab pages when
CONFIG_DEBUG_VM is enabled.  As neither lru, nor kmem, nor slab page
should have anything left in there by the time the page is freed, what
we care about is whether the value of page->memcg_data is 0.  So just
directly access page->memcg_data here.

Link: https://lkml.kernel.org/r/20210319163821.20704-4-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chen Huang <chenhuang5@huawei.com>
---
 mm/page_alloc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8ec194271b91..12deac86a7ac 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1094,7 +1094,7 @@ static inline bool page_expected_state(struct page *page,
 	if (unlikely((unsigned long)page->mapping |
 			page_ref_count(page) |
 #ifdef CONFIG_MEMCG
-			(unsigned long)page_memcg(page) |
+			page->memcg_data |
 #endif
 			(page->flags & check_flags)))
 		return false;
@@ -1119,7 +1119,7 @@ static const char *page_bad_reason(struct page *page, unsigned long flags)
 			bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
 	}
 #ifdef CONFIG_MEMCG
-	if (unlikely(page_memcg(page)))
+	if (unlikely(page->memcg_data))
 		bad_reason = "page still charged to cgroup";
 #endif
 	return bad_reason;
-- 
2.18.0.huawei.25