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Mon, 12 Apr 2021 10:41:59 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.171.95.131]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 12 Apr 2021 10:41:59 +0000 (GMT) Subject: Re: [PATCH] mm: memcontrol: fix forget to obtain the ref to objcg in split_page_memcg To: Muchun Song , guro@fb.com, hannes@cmpxchg.org, mhocko@kernel.org, akpm@linux-foundation.org, shakeelb@google.com, vdavydov.dev@gmail.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, duanxiongchun@bytedance.com, linux-s390 References: <20210401030141.37061-1-songmuchun@bytedance.com> From: Christian Borntraeger Message-ID: <4b9c1b0c-00dc-97e0-0e17-b8467c4cb31d@de.ibm.com> Date: Mon, 12 Apr 2021 12:41:58 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210401030141.37061-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 1KiD-rl0PhP2cwWbZnMev6I_g60z-88z X-Proofpoint-GUID: jTs7x_s6nucT66gw7uGCxa_KLepHMnd8 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-04-12_09:2021-04-12,2021-04-12 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 suspectscore=0 spamscore=0 bulkscore=0 adultscore=0 phishscore=0 mlxscore=0 lowpriorityscore=0 priorityscore=1501 mlxlogscore=999 malwarescore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104120065 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: DA37BA000398 X-Stat-Signature: uw8t8wopya5aic9nycgjpohotrgezpdm Received-SPF: none (de.ibm.com>: No applicable sender policy available) receiver=imf07; identity=mailfrom; envelope-from=""; helo=mx0a-001b2d01.pphosted.com; client-ip=148.163.158.5 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618224129-28341 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: FWIW, I was away the last week, and I checked yesterdays next (e99d8a849517) regression runs. I still do see errors in our CI system: [ 2263.021681] ------------[ cut here ]------------ [ 2263.021697] percpu ref (obj_cgroup_release) <= 0 (0) after switching to atomic [ 2263.021748] WARNING: CPU: 4 PID: 0 at lib/percpu-refcount.c:196 percpu_ref_switch_to_atomic_rcu+0x1ea/0x1f8 [ 2263.021756] Modules linked in: scsi_debug vfio_pci irqbypass vfio_virqfd kvm vhost_vsock vmw_vsock_virtio_transport_common vsock vhost vhost_iotlb xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT xt_tcpudp nft_compat nf_nat_tftp nft_objref nf_conntrack_tftp nft_counter bridge stp llc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables nfnetlink dm_service_time zfcp scsi_transport_fc dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua rpcrdma sunrpc rdma_ucm rdma_cm iw_cm ib_cm mlx5_ib dm_mod ib_uverbs ib_core s390_trng vfio_ccw vfio_mdev mdev vfio_iommu_type1 vfio eadm_sch zcrypt_cex4 sch_fq_codel configfs ip_tables x_tables ghash_s390 prng aes_s390 des_s390 libdes sha3_512_s390 sha3_256_s390 mlx5_core sha512_s390 sha256_s390 sha1_s390 sha_common nvme nvme_core pkey zcrypt rng_core autofs4 [last unloaded: vfio_ap] [ 2263.021820] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 5.12.0-20210412.rc6.git0.e99d8a849517.300.fc33.s390x+next #1 [ 2263.021823] Hardware name: IBM 8561 T01 703 (LPAR) [ 2263.021825] Krnl PSW : 0704c00180000000 000000025b234c1e (percpu_ref_switch_to_atomic_rcu+0x1ee/0x1f8) [ 2263.021829] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 [ 2263.021832] Krnl GPRS: c0000000fffeffff 00000002f7212818 0000000000000042 00000000fffeffff [ 2263.021834] 00000000ffffffea 0000038000000001 0000000000000000 000003800000017c [ 2263.021836] 000000025b980988 00000000b774d0e0 000003fee191d5d8 8000000000000000 [ 2263.021838] 000000008034c000 00000002f7227570 000000025b234c1a 00000380000aba28 [ 2263.021849] Krnl Code: 000000025b234c0e: e3309fe8ff04 lg %r3,-24(%r9) 000000025b234c14: c0e5001ebe92 brasl %r14,000000025b60c938 #000000025b234c1a: af000000 mc 0,0 >000000025b234c1e: a7f4ffcc brc 15,000000025b234bb6 000000025b234c22: 0707 bcr 0,%r7 000000025b234c24: 0707 bcr 0,%r7 000000025b234c26: 0707 bcr 0,%r7 000000025b234c28: eb6ff0480024 stmg %r6,%r15,72(%r15) [ 2263.021912] Call Trace: [ 2263.021914] [<000000025b234c1e>] percpu_ref_switch_to_atomic_rcu+0x1ee/0x1f8 [ 2263.021917] ([<000000025b234c1a>] percpu_ref_switch_to_atomic_rcu+0x1ea/0x1f8) [ 2263.021919] [<000000025abe16fe>] rcu_do_batch+0x146/0x608 [ 2263.021924] [<000000025abe5ff4>] rcu_core+0x124/0x1d0 [ 2263.021926] [<000000025b62a222>] __do_softirq+0x13a/0x3c8 [ 2263.021930] [<000000025ab5d3f6>] irq_exit+0xce/0xf8 [ 2263.021934] [<000000025b61a5f6>] do_ext_irq+0xd6/0x160 [ 2263.021937] [<000000025b627c3c>] ext_int_handler+0xc4/0xf4 [ 2263.021939] [<0000000000000000>] 0x0 [ 2263.021943] [<000000025b62775a>] default_idle_call+0x42/0x110 [ 2263.021945] [<000000025ab99328>] do_idle+0xd8/0x168 [ 2263.021949] [<000000025ab99576>] cpu_startup_entry+0x36/0x40 [ 2263.021952] [<000000025ab1f33a>] smp_start_secondary+0x82/0x88 [ 2263.021955] Last Breaking-Event-Address: [ 2263.021955] [<000000025abc8828>] vprintk_emit+0xa8/0x110 [ 2263.021961] Kernel panic - not syncing: panic_on_warn set ... [ 2263.021962] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 5.12.0-20210412.rc6.git0.e99d8a849517.300.fc33.s390x+next #1 [ 2263.021964] Hardware name: IBM 8561 T01 703 (LPAR) [ 2263.021965] Call Trace: [ 2263.021966] [<000000025b60bc9a>] show_stack+0x92/0xd8 [ 2263.021972] [<000000025b6161c0>] dump_stack+0x90/0xc0 [ 2263.021975] [<000000025b60cab2>] panic+0x112/0x308 [ 2263.021977] [<000000025ab5571a>] __warn+0xc2/0x158 [ 2263.021981] [<000000025b2a5e4a>] report_bug+0xb2/0x130 [ 2263.021984] [<000000025ab09ef4>] monitor_event_exception+0x44/0xc0 [ 2263.021986] [<000000025b61a1e8>] __do_pgm_check+0xe0/0x1f0 [ 2263.021988] [<000000025b627b30>] pgm_check_handler+0x118/0x160 [ 2263.021990] [<000000025b234c1e>] percpu_ref_switch_to_atomic_rcu+0x1ee/0x1f8 [ 2263.021992] ([<000000025b234c1a>] percpu_ref_switch_to_atomic_rcu+0x1ea/0x1f8) [ 2263.021993] [<000000025abe16fe>] rcu_do_batch+0x146/0x608 [ 2263.021995] [<000000025abe5ff4>] rcu_core+0x124/0x1d0 [ 2263.021997] [<000000025b62a222>] __do_softirq+0x13a/0x3c8 [ 2263.021998] [<000000025ab5d3f6>] irq_exit+0xce/0xf8 [ 2263.022000] [<000000025b61a5f6>] do_ext_irq+0xd6/0x160 [ 2263.022001] [<000000025b627c3c>] ext_int_handler+0xc4/0xf4 [ 2263.022003] [<0000000000000000>] 0x0 [ 2263.022004] [<000000025b62775a>] default_idle_call+0x42/0x110 [ 2263.022006] [<000000025ab99328>] do_idle+0xd8/0x168 [ 2263.022008] [<000000025ab99576>] cpu_startup_entry+0x36/0x40 So either the fix was not complete or it is still missing in next.