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Fri, 16 Apr 2021 11:28:00 GMT Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by ppma06ams.nl.ibm.com with ESMTP id 37u39hmeet-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 16 Apr 2021 11:28:00 +0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 13GBRvdR26673634 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 16 Apr 2021 11:27:58 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DF50FAE04D; Fri, 16 Apr 2021 11:27:57 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 971D3AE045; Fri, 16 Apr 2021 11:27:56 +0000 (GMT) Received: from [9.85.105.90] (unknown [9.85.105.90]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 16 Apr 2021 11:27:56 +0000 (GMT) Subject: Re: [PATCH] powerpc/kdump: fix kdump kernel hangup issue with hot add CPUs To: Hari Bathini , mpe@ellerman.id.au References: <20210416064749.657585-1-sourabhjain@linux.ibm.com> From: Sourabh Jain Message-ID: Date: Fri, 16 Apr 2021 16:57:55 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-GUID: UdCNW3Y-ypBMuu1CQoaXJjnk9xkFQfD7 X-Proofpoint-ORIG-GUID: UdCNW3Y-ypBMuu1CQoaXJjnk9xkFQfD7 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-04-16_06:2021-04-15, 2021-04-16 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 priorityscore=1501 phishscore=0 malwarescore=0 impostorscore=0 adultscore=0 bulkscore=0 suspectscore=0 spamscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104160083 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mahesh@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 16/04/21 3:03 pm, Hari Bathini wrote: > > > On 16/04/21 12:17 pm, Sourabh Jain wrote: >> With the kexec_file_load system call when system crashes on the hot add >> CPU the capture kernel hangs and failed to collect the vmcore. >> >>   Kernel panic - not syncing: sysrq triggered crash >>   CPU: 24 PID: 6065 Comm: echo Kdump: loaded Not tainted >> 5.12.0-rc5upstream #54 >>   Call Trace: >>   [c0000000e590fac0] [c0000000007b2400] dump_stack+0xc4/0x114 >> (unreliable) >>   [c0000000e590fb00] [c000000000145290] panic+0x16c/0x41c >>   [c0000000e590fba0] [c0000000008892e0] sysrq_handle_crash+0x30/0x40 >>   [c0000000e590fc00] [c000000000889cdc] __handle_sysrq+0xcc/0x1f0 >>   [c0000000e590fca0] [c00000000088a538] write_sysrq_trigger+0xd8/0x178 >>   [c0000000e590fce0] [c0000000005e9b7c] proc_reg_write+0x10c/0x1b0 >>   [c0000000e590fd10] [c0000000004f26d0] vfs_write+0xf0/0x330 >>   [c0000000e590fd60] [c0000000004f2aec] ksys_write+0x7c/0x140 >>   [c0000000e590fdb0] [c000000000031ee0] >> system_call_exception+0x150/0x290 >>   [c0000000e590fe10] [c00000000000ca5c] system_call_common+0xec/0x278 >>   --- interrupt: c00 at 0x7fff905b9664 >>   NIP:  00007fff905b9664 LR: 00007fff905320c4 CTR: 0000000000000000 >>   REGS: c0000000e590fe80 TRAP: 0c00   Not tainted (5.12.0-rc5upstream) >>   MSR:  800000000280f033   CR: >> 28000242 >>         XER: 00000000 >>   IRQMASK: 0 >>   GPR00: 0000000000000004 00007ffff5fedf30 00007fff906a7300 >> 0000000000000001 >>   GPR04: 000001002a7355b0 0000000000000002 0000000000000001 >> 00007ffff5fef616 >>   GPR08: 0000000000000001 0000000000000000 0000000000000000 >> 0000000000000000 >>   GPR12: 0000000000000000 00007fff9073a160 0000000000000000 >> 0000000000000000 >>   GPR16: 0000000000000000 0000000000000000 0000000000000000 >> 0000000000000000 >>   GPR20: 0000000000000000 00007fff906a4ee0 0000000000000002 >> 0000000000000001 >>   GPR24: 00007fff906a0898 0000000000000000 0000000000000002 >> 000001002a7355b0 >>   GPR28: 0000000000000002 00007fff906a1790 000001002a7355b0 >> 0000000000000002 >>   NIP [00007fff905b9664] 0x7fff905b9664 >>   LR [00007fff905320c4] 0x7fff905320c4 >>   --- interrupt: c00 > > > > I will update the commit message. > >>   /** >>    * setup_new_fdt_ppc64 - Update the flattend device-tree of the kernel >>    *                       being loaded. >> @@ -1020,6 +1113,13 @@ int setup_new_fdt_ppc64(const struct kimage >> *image, void *fdt, >>           } >>       } >>   +    /* Update cpus nodes information to account hotplug CPUs. */ >> +    if (image->type == KEXEC_TYPE_CRASH) { > > Shouldn't this apply to regular kexec_file_load case as well? Yeah, > there won't be a hang in regular kexec_file_load case but for > correctness, that kernel should also not see stale CPU info in FDT? > > Yes better to update the fdt for both kexec and kdump. > > Thanks for the review Hari. > > - Sourabh Jain