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Wed, 25 Nov 2020 12:15:17 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04420;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0UGVZDcx_1606306511; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0UGVZDcx_1606306511) by smtp.aliyun-inc.com(127.0.0.1); Wed, 25 Nov 2020 20:15:11 +0800 Subject: Re: [PATCH] mm/memcg: warn on missing memcg on mem_cgroup_page_lruvec() To: Lorenzo Stoakes , Johannes Weiner , Hui Su , Stephen Rothwell , Shakeel Butt , Roman Gushchin Cc: syzbot , Linux Kernel Mailing List , linux-mm , Linux-Next Mailing List , syzkaller-bugs References: <00000000000054aea005b4d59e71@google.com> <20201125112202.387009-1-lstoakes@gmail.com> From: Alex Shi Message-ID: <0918d6f5-8459-7b5e-82a3-6c9792d17433@linux.alibaba.com> Date: Wed, 25 Nov 2020 20:15:11 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201125112202.387009-1-lstoakes@gmail.com> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Acked-by: Alex Shi =D4=DA 2020/11/25 =CF=C2=CE=E77:22, Lorenzo Stoakes =D0=B4=B5=C0: > Move memcg check to mem_cgroup_page_lruvec() as there are callers which > may invoke this with !memcg in mem_cgroup_lruvec(), whereas they should > not in mem_cgroup_page_lruvec(). >=20 > We expect that we have always charged a page to the memcg before > mem_cgroup_page_lruvec() is invoked, so add a warning to assert that th= is > is the case. >=20 > Signed-off-by: Lorenzo Stoakes > Reported-by: syzbot+ce635500093181f39c1c@syzkaller.appspotmail.com > --- > include/linux/memcontrol.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) >=20 > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 87ed56dc75f9..3e6a1df3bdb9 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -618,7 +618,6 @@ static inline struct lruvec *mem_cgroup_lruvec(stru= ct mem_cgroup *memcg, > goto out; > } > =20 > - VM_WARN_ON_ONCE(!memcg); > if (!memcg) > memcg =3D root_mem_cgroup; > =20 > @@ -645,7 +644,10 @@ static inline struct lruvec *mem_cgroup_lruvec(str= uct mem_cgroup *memcg, > static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page, > struct pglist_data *pgdat) > { > - return mem_cgroup_lruvec(page_memcg(page), pgdat); > + struct mem_cgroup *memcg =3D page_memcg(page); > + > + VM_WARN_ON_ONCE_PAGE(!memcg, page); > + return mem_cgroup_lruvec(memcg, pgdat); > } > =20 > static inline bool lruvec_holds_page_lru_lock(struct page *page, >=20