From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e33.co.us.ibm.com (e33.co.us.ibm.com [32.97.110.151]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 07ABD1A0232 for ; Tue, 10 Nov 2015 03:35:33 +1100 (AEDT) Received: from localhost by e33.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 9 Nov 2015 09:35:30 -0700 Received: from b03cxnp08027.gho.boulder.ibm.com (b03cxnp08027.gho.boulder.ibm.com [9.17.130.19]) by d03dlp02.boulder.ibm.com (Postfix) with ESMTP id 0682D3E4003F for ; Mon, 9 Nov 2015 09:35:16 -0700 (MST) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id tA9GZF6756492048 for ; Mon, 9 Nov 2015 09:35:15 -0700 Received: from d03av01.boulder.ibm.com (localhost [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id tA9GZF0e007387 for ; Mon, 9 Nov 2015 09:35:15 -0700 Subject: Re: [PATCH v2] memory-hotplug: Fix kernel warning during memory hotplug on ppc64 To: John Allen , gregkh@linuxfoundation.org References: <5638ED37.3090500@linux.vnet.ibm.com> Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org From: Nathan Fontenot Message-ID: <5640CB42.8000400@linux.vnet.ibm.com> Date: Mon, 9 Nov 2015 10:35:14 -0600 MIME-Version: 1.0 In-Reply-To: <5638ED37.3090500@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 11/03/2015 11:21 AM, John Allen wrote: > 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 Reviewed-by: Nathan Fontenot > --- > 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; > } >