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[66.187.233.206]) by smtp.gmail.com with ESMTPSA id e18sm893339qkm.49.2019.06.28.06.00.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 28 Jun 2019 06:00:55 -0700 (PDT) Message-ID: <1561726853.5154.100.camel@lca.pw> Subject: Re: power9 NUMA crash while reading debugfs imc_cmd From: Qian Cai To: Anju T Sudhakar Cc: Michael Ellerman , "Aneesh Kumar K.V" , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Date: Fri, 28 Jun 2019 09:00:53 -0400 In-Reply-To: <9c87dc72-54f8-8510-c400-1e89779cc88b@linux.vnet.ibm.com> References: <1561670472.5154.98.camel@lca.pw> <87lfxms8r3.fsf@concordia.ellerman.id.au> <715A934D-EE3A-478B-BA77-589C539FC52D@lca.pw> <9c87dc72-54f8-8510-c400-1e89779cc88b@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6 (3.22.6-10.el7) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2019-06-28 at 17:19 +0530, Anju T Sudhakar wrote: > On 6/28/19 9:04 AM, Qian Cai wrote: > > > > > On Jun 27, 2019, at 11:12 PM, Michael Ellerman wrote: > > > > > > Qian Cai writes: > > > > Read of debugfs imc_cmd file for a memory-less node will trigger a crash > > > > below > > > > on this power9 machine which has the following NUMA layout. > > > > > > What type of machine is it? > > > > description: PowerNV > > product: 8335-GTH (ibm,witherspoon) > > vendor: IBM > > width: 64 bits > > capabilities: smp powernv opal > > > Hi Qian Cai, > > Could you please try with this patch:  > https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-June/192803.html > > and see if the issue is resolved? It works fine. Just feel a bit silly that a node without CPU and memory is still online by default during boot at the first place on powerpc, but that is probably a different issue. For example, # numactl -H available: 6 nodes (0,8,252-255) node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 node 0 size: 126801 MB node 0 free: 123199 MB node 8 cpus: 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 node 8 size: 130811 MB node 8 free: 128436 MB node 252 cpus: node 252 size: 0 MB node 252 free: 0 MB node 253 cpus: node 253 size: 0 MB node 253 free: 0 MB node 254 cpus: node 254 size: 0 MB node 254 free: 0 MB node 255 cpus: node 255 size: 0 MB node 255 free: 0 MB node distances: node   0   8  252  253  254  255    0:  10  40  80  80  80  80    8:  40  10  80  80  80  80   252:  80  80  10  80  80  80   253:  80  80  80  10  80  80   254:  80  80  80  80  10  80   255:  80  80  80  80  80  10  # cat /sys/devices/system/node/online  0,8,252-255