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[90.224.45.44]) by smtp.gmail.com with ESMTPSA id g25-20020a170906595900b00877ef618b35sm5182750ejr.145.2023.01.29.02.38.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 29 Jan 2023 02:38:52 -0800 (PST) Message-ID: <27176f7a24fb37e5f011c7fa451bec7ba324e668.camel@gmail.com> Subject: Re: [PATCH resend] mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty_slowpath() From: mikoxyzzz@gmail.com To: Kefeng Wang , Andrew Morton Cc: Tejun Heo , Jens Axboe , Jan Kara , Shakeel Butt , Naoya Horiguchi , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ma Wupeng Date: Sun, 29 Jan 2023 11:38:51 +0100 In-Reply-To: <20230129040945.180629-1-wangkefeng.wang@huawei.com> References: <20230129024451.121590-1-wangkefeng.wang@huawei.com> <20230129040945.180629-1-wangkefeng.wang@huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.46.3 (3.46.3-1.module_f37+15877+cf3308f9) MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Queue-Id: DE32B100009 X-Rspamd-Server: rspam01 X-Stat-Signature: sd1zds47yx6b8if5tn3qaepzq5o4tmej X-HE-Tag: 1674988734-414049 X-HE-Meta: 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 7+mRpVCG 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 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: On Sun, 2023-01-29 at 12:09 +0800, Kefeng Wang wrote: > As commit 18365225f044 ("hwpoison, memcg: forcibly uncharge LRU > pages"), > hwpoison will forcibly uncharg a LRU hwpoisoned page, the folio_memcg > could be NULl, then, mem_cgroup_track_foreign_dirty_slowpath() could > occurs a NULL pointer dereference, let's do not record the foreign > writebacks for folio memcg is null in > mem_cgroup_track_foreign_dirty() > to fix it. >=20 > Reported-by: Ma Wupeng > Fixes: 97b27821b485 ("writeback, memcg: Implement foreign dirty > flushing") > Signed-off-by: Kefeng Wang > --- > resend: correct function name > =C2=A0include/linux/memcontrol.h | 5 ++++- > =C2=A01 file changed, 4 insertions(+), 1 deletion(-) >=20 > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index eb6e5b18e1ad..35478695cabf 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -1688,10 +1688,13 @@ void > mem_cgroup_track_foreign_dirty_slowpath(struct folio *folio, > =C2=A0static inline void mem_cgroup_track_foreign_dirty(struct folio > *folio, > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 st= ruct > bdi_writeback *wb) > =C2=A0{ > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0struct mem_cgroup *memcg; > + > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (mem_cgroup_disabled()= ) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0return; > =C2=A0 > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (unlikely(&folio_memcg(foli= o)->css !=3D wb->memcg_css)) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0memcg =3D folio_memcg(folio); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (unlikely(memcg && &memcg->= css !=3D wb->memcg_css)) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0mem_cgroup_track_foreign_dirty_slowpath(folio, wb); > =C2=A0} > =C2=A0 Might want to Cc linux-stable. Tested-by: Miko Larsson -- ~miko