Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755545AbbKCRWK (ORCPT ); Tue, 3 Nov 2015 12:22:10 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:59254 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754645AbbKCRWF (ORCPT ); Tue, 3 Nov 2015 12:22:05 -0500 X-IBM-Helo: d03dlp02.boulder.ibm.com X-IBM-MailFrom: jallen@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: John Allen Subject: [PATCH v2] memory-hotplug: Fix kernel warning during memory hotplug on ppc64 To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Nathan Fontenot Message-ID: <5638ED37.3090500@linux.vnet.ibm.com> Date: Tue, 3 Nov 2015 11:21:59 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15110317-0029-0000-0000-00000DD8A6D2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4467 Lines: 82 This patch fixes a bug where a kernel warning is triggered when performing a memory hotplug on ppc64. This warning may also occur on any architecture that has multiple sections per memory block. [ 78.300767] ------------[ cut here ]------------ [ 78.300768] WARNING: at ../drivers/base/memory.c:210 [ 78.300769] Modules linked in: rpadlpar_io(X) rpaphp(X) tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag af_packet xfs libcrc32c ibmveth(X) rtc_generic btrfs xor raid6_pq xts gf128mul dm_crypt sd_mod sr_mod cdrom crc_t10dif ibmvscsi(X) scsi_transport_srp scsi_tgt dm_mod sg scsi_mod autofs4 [ 78.300789] Supported: Yes, External [ 78.300791] CPU: 1 PID: 3090 Comm: systemd-udevd Tainted: G X 3.12.45-1-default #1 [ 78.300793] task: c0000004d7d1d970 ti: c0000004d7b90000 task.ti: c0000004d7b90000 [ 78.300794] NIP: c0000000004fcff8 LR: c0000000004fda84 CTR: 0000000000000000 [ 78.300795] REGS: c0000004d7b93930 TRAP: 0700 Tainted: G X (3.12.45-1-default) [ 78.300796] MSR: 8000000000029033 CR: 24088848 XER: 00000000 [ 78.300800] CFAR: c0000000004fcf98 SOFTE: 1 GPR00: 0000000000000537 c0000004d7b93bb0 c000000000e7f200 0000000000053000 GPR04: 0000000000001000 0000000000000001 c000000000e0f200 0000000000000000 GPR08: 0000000000000000 0000000000000001 0000000000000537 00000000014dc000 GPR12: 0000000000054000 c00000000e7f0900 0000000010041040 0000000000000000 GPR16: 00000100206f0010 000000001003ff78 000000001006c824 00000000100410b0 GPR20: 000000001003ff90 000000001006c00c 000001002073cd20 00000100206f0760 GPR24: 00000100206f85a0 c00000000076d950 c0000004ef7c95e0 c0000004d7b93e00 GPR28: c0000004de601738 0000000000000001 c000000001218f80 00000000003fffff [ 78.300818] NIP [c0000000004fcff8] memory_block_action+0x258/0x2e0 [ 78.300820] LR [c0000000004fda84] memory_subsys_online+0x54/0x100 [ 78.300821] Call Trace: [ 78.300822] [c0000004d7b93bb0] [c000000009071ce0] 0xc000000009071ce0 (unreliable) [ 78.300824] [c0000004d7b93c40] [c0000000004fda84] memory_subsys_online+0x54/0x100 [ 78.300826] [c0000004d7b93c70] [c0000000004df784] device_online+0xb4/0x120 [ 78.300828] [c0000004d7b93cb0] [c0000000004fd738] store_mem_state+0x88/0x220 [ 78.300830] [c0000004d7b93cf0] [c0000000004db448] dev_attr_store+0x68/0xa0 [ 78.300833] [c0000004d7b93d30] [c00000000031f938] sysfs_write_file+0xf8/0x1d0 [ 78.300835] [c0000004d7b93d90] [c00000000027d29c] vfs_write+0xec/0x250 [ 78.300837] [c0000004d7b93de0] [c00000000027dfdc] SyS_write+0x6c/0xf0 [ 78.300839] [c0000004d7b93e30] [c00000000000a17c] syscall_exit+0x0/0x7c [ 78.300840] Instruction dump: [ 78.300841] 780a0560 79482ea4 7ce94214 2fa70000 41de0014 7d09402a 396b4000 7907ffe3 [ 78.300844] 4082ff54 3cc2fff9 8926b83a 69290001 <0b090000> 2fa90000 40de006c 3860fff0 [ 78.300847] ---[ end trace dfec8da06ebbc762 ]--- The warning is triggered because there is a udev rule that automatically tries to online memory after it has been added. The udev rule varies from distro to distro, but will generally look something like: SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online" On any architecture that uses memory_probe_store to reserve memory, this can interrupt the memory reservation process. This patch modifies memory_probe_store to take the hotplug sysfs lock to prevent the online of added memory before the completion of the probe. Signed-off-by: John Allen --- v2: Move call to unlock_device_hotplug under "out" label diff --git a/drivers/base/memory.c b/drivers/base/memory.c index bece691..7c50415 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -422,6 +422,10 @@ memory_probe_store(struct device *dev, struct device_attribute *attr, if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1)) return -EINVAL; + ret = lock_device_hotplug_sysfs(); + if (ret) + return ret; + for (i = 0; i < sections_per_block; i++) { nid = memory_add_physaddr_to_nid(phys_addr); ret = add_memory(nid, phys_addr, @@ -434,6 +438,7 @@ memory_probe_store(struct device *dev, struct device_attribute *attr, ret = count; out: + unlock_device_hotplug(); return ret; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/