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Date: Thu, 9 Dec 2010 08:09:45 +0800 From: Shaohui Zheng <shaohui.zheng@...el.com> To: Eric B Munson <emunson@...bm.net> Cc: Shaohui Zheng <shaohui.zheng@...ux.intel.com>, akpm@...ux-foundation.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, haicheng.li@...ux.intel.com, lethal@...ux-sh.org, ak@...ux.intel.com, rientjes@...gle.com, dave@...ux.vnet.ibm.com, gregkh@...e.de, Haicheng Li <haicheng.li@...el.com> Subject: Re: [1/7,v8] NUMA Hotplug Emulator: documentation On Wed, Dec 08, 2010 at 10:46:33AM -0700, Eric B Munson wrote: > Shaohui, > > I have had some success. I had run into confusion on the memory hotplug with > which files to be using to online memory. The latest patch sorted it out for me > and I can now online disabled memory in new nodes. I still cannot online an offlined > cpu. Of the 12 available thread, I have 8 activated on boot with the kernel command line: > > mem=8G numa=possible=12 maxcpus=8 cpu_hpe=on > > I can offline a CPU just fine according to the kernel: > root@...t:/sys/devices/system/cpu# echo 7 > release > (dmesg) > [ 911.494852] offline cpu 7. > [ 911.694323] CPU 7 is now offline > > But when I try and re-add it I get an error: > root@...t:/sys/devices/system/cpu# echo 0 > probe > (dmesg) > Dec 8 10:41:55 bert kernel: [ 1190.095051] ------------[ cut here ]------------ > Dec 8 10:41:55 bert kernel: [ 1190.095056] WARNING: at fs/sysfs/dir.c:451 sysfs_add_one+0xce/0x180() > Dec 8 10:41:55 bert kernel: [ 1190.095057] Hardware name: System Product Name > Dec 8 10:41:55 bert kernel: [ 1190.095058] sysfs: cannot create duplicate filename '/devices/system/cpu/cpu7' > Dec 8 10:41:55 bert kernel: [ 1190.095060] Modules linked in: nfs binfmt_misc lockd fscache nfs_acl auth_rpcgss sunrpc snd_hda_codec_hdmi snd_hda_codec_realtek radeon snd_hda_intel snd_hda_codec snd_cmipci gameport snd_pcm ttm snd_opl3_lib drm_kms_helper snd_hwdep snd_mpu401_uart drm uvcvideo snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq xhci_hcd snd_timer videodev snd_seq_device snd psmouse i7core_edac i2c_algo_bit edac_core joydev v4l1_compat shpchp snd_page_alloc v4l2_compat_ioctl32 soundcore hwmon_vid asus_atk0110 max6650 serio_raw hid_microsoft usbhid hid firewire_ohci firewire_core crc_itu_t ahci sky2 libahci > Dec 8 10:41:55 bert kernel: [ 1190.095088] Pid: 2369, comm: bash Tainted: G W 2.6.37-rc5-numa-test+ #3 > Dec 8 10:41:55 bert kernel: [ 1190.095089] Call Trace: > Dec 8 10:41:55 bert kernel: [ 1190.095094] [<ffffffff8105eb1f>] warn_slowpath_common+0x7f/0xc0 > Dec 8 10:41:55 bert kernel: [ 1190.095096] [<ffffffff8105ec16>] warn_slowpath_fmt+0x46/0x50 > Dec 8 10:41:55 bert kernel: [ 1190.095098] [<ffffffff811cf77e>] sysfs_add_one+0xce/0x180 > Dec 8 10:41:55 bert kernel: [ 1190.095100] [<ffffffff811cf8b1>] create_dir+0x81/0xd0 > Dec 8 10:41:55 bert kernel: [ 1190.095102] [<ffffffff811cf97d>] sysfs_create_dir+0x7d/0xd0 > Dec 8 10:41:55 bert kernel: [ 1190.095106] [<ffffffff815a2b3d>] ? sub_preempt_count+0x9d/0xd0 > Dec 8 10:41:55 bert kernel: [ 1190.095109] [<ffffffff812c9ffd>] kobject_add_internal+0xbd/0x200 > Dec 8 10:41:55 bert kernel: [ 1190.095111] [<ffffffff812ca258>] kobject_add_varg+0x38/0x60 > Dec 8 10:41:55 bert kernel: [ 1190.095113] [<ffffffff812ca2d3>] kobject_init_and_add+0x53/0x70 > Dec 8 10:41:55 bert kernel: [ 1190.095117] [<ffffffff8139475f>] sysdev_register+0x6f/0xf0 > Dec 8 10:41:55 bert kernel: [ 1190.095121] [<ffffffff81598f38>] register_cpu_node+0x32/0x88 > Dec 8 10:41:55 bert kernel: [ 1190.095123] [<ffffffff8158207e>] arch_register_cpu_node+0x3e/0x40 > Dec 8 10:41:55 bert kernel: [ 1190.095127] [<ffffffff8101220e>] arch_cpu_probe+0x10e/0x1f0 > Dec 8 10:41:55 bert kernel: [ 1190.095129] [<ffffffff813989d4>] cpu_probe_store+0x14/0x20 > Dec 8 10:41:55 bert kernel: [ 1190.095131] [<ffffffff81393ef0>] sysdev_class_store+0x20/0x30 > Dec 8 10:41:55 bert kernel: [ 1190.095133] [<ffffffff811cd925>] sysfs_write_file+0xe5/0x170 > Dec 8 10:41:55 bert kernel: [ 1190.095137] [<ffffffff811624c8>] vfs_write+0xc8/0x190 > Dec 8 10:41:55 bert kernel: [ 1190.095139] [<ffffffff81162e61>] sys_write+0x51/0x90 > Dec 8 10:41:55 bert kernel: [ 1190.095142] [<ffffffff8100c142>] system_call_fastpath+0x16/0x1b > Dec 8 10:41:55 bert kernel: [ 1190.095144] ---[ end trace f615c2a524d318ea ]--- > Dec 8 10:41:55 bert kernel: [ 1190.095149] Pid: 2369, comm: bash Tainted: G W 2.6.37-rc5-numa-test+ #3 > Dec 8 10:41:55 bert kernel: [ 1190.095150] Call Trace: > Dec 8 10:41:55 bert kernel: [ 1190.095152] [<ffffffff812ca09b>] kobject_add_internal+0x15b/0x200 > Dec 8 10:41:55 bert kernel: [ 1190.095154] [<ffffffff812ca258>] kobject_add_varg+0x38/0x60 > Dec 8 10:41:55 bert kernel: [ 1190.095156] [<ffffffff812ca2d3>] kobject_init_and_add+0x53/0x70 > Dec 8 10:41:55 bert kernel: [ 1190.095158] [<ffffffff8139475f>] sysdev_register+0x6f/0xf0 > Dec 8 10:41:55 bert kernel: [ 1190.095160] [<ffffffff81598f38>] register_cpu_node+0x32/0x88 > Dec 8 10:41:55 bert kernel: [ 1190.095162] [<ffffffff8158207e>] arch_register_cpu_node+0x3e/0x40 > Dec 8 10:41:55 bert kernel: [ 1190.095164] [<ffffffff8101220e>] arch_cpu_probe+0x10e/0x1f0 > Dec 8 10:41:55 bert kernel: [ 1190.095166] [<ffffffff813989d4>] cpu_probe_store+0x14/0x20 > Dec 8 10:41:55 bert kernel: [ 1190.095168] [<ffffffff81393ef0>] sysdev_class_store+0x20/0x30 > Dec 8 10:41:55 bert kernel: [ 1190.095170] [<ffffffff811cd925>] sysfs_write_file+0xe5/0x170 > Dec 8 10:41:55 bert kernel: [ 1190.095172] [<ffffffff811624c8>] vfs_write+0xc8/0x190 > Dec 8 10:41:55 bert kernel: [ 1190.095174] [<ffffffff81162e61>] sys_write+0x51/0x90 > Dec 8 10:41:55 bert kernel: [ 1190.095176] [<ffffffff8100c142>] system_call_fastpath+0x16/0x1b > > Am I doing something wrong? > > Thanks, > Eric Eric, I saw that you already get this issue solved in another email, that is good. I double check your step, and I did not find any problems. the logic to do CPU release(arch_cpu_release), 1) offline the CPU if the CPU is online 2) unregister CPU so even if the CPU is online, you can still release the CPU directly. I should check the return value after call cpu_down. How about add the following checking? --- arch/x86/kernel/topology.c-orig 2010-12-09 08:03:19.883331001 +0800 +++ arch/x86/kernel/topology.c 2010-12-09 08:01:35.993331000 +0800 @@ -158,7 +158,10 @@ if (cpu_online(cpu)) { printk(KERN_DEBUG "offline cpu %d.\n", cpu); - cpu_down(cpu); + if (!cpu_down(cpu)){ + printk(KERN_ERR "fail to offline cpu %d, give up.\n", cpu); + return -EPERM; + } } arch_unregister_cpu(cpu); -- Thanks & Regards, Shaohui -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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