From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: patch "x86/cpufreq: relocate the driver register function" breaks cpu hot(un)plug Date: Fri, 9 Oct 2015 18:48:23 +0200 Message-ID: <1444409303.3009.5.camel@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0886449616970044378==" Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1ZkaqZ-0001bo-S3 for xen-devel@lists.xenproject.org; Fri, 09 Oct 2015 16:48:44 +0000 List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "xen-devel@lists.xenproject.org" Cc: Wei Wang , Jan Beulich List-Id: xen-devel@lists.xenproject.org --===============0886449616970044378== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-76TmArXHlFJxw2YytoM4" --=-76TmArXHlFJxw2YytoM4 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hey, As far as my bisection goes, commit 49388f11d512bb92706ce046643bfbb3c1d963c9 "x86/cpufreq: relocate the driver register function" prevents me from hot unplugging pCPUs. Xen does not crash or anything, but dom0 is stalled. In fact, with current staging, here's what I see: root@Zhaman:~# echo 0 > /sys/devices/system/xen_cpu/xen_cpu6/online=20 [ 81.583001] INFO: rcu_sched detected stalls on CPUs/tasks: { 12} (detect= ed by 3, t=3D5252 jiffies, g=3D1691, c=3D1690, q=3D76) [ 81.583036] Task dump for CPU 12: [ 81.583044] bash R running task 0 1347 1094 0x0000= 0008 [ 81.583056] ffffffff00000000 0000000000000000 0000000000000000 ffff8800= 192c2e38 [ 81.583070] ffff8800008472e8 0000000000000002 ffff8800008472e8 ffff8800= 13817858 [ 81.583082] 0000000000000000 00000000000081a4 ffffffff811e8137 ffff8800= 192c2e38 [ 81.583095] Call Trace: [ 81.583110] [] ? notify_change+0x2f7/0x390 [ 81.583148] [] ? do_truncate+0x74/0x90 [ 81.583158] [] ? dput+0x26/0x230 [ 81.583167] [] ? terminate_walk+0x35/0x40 [ 81.583176] [] ? do_last+0x621/0x12c0 [ 81.583188] [] ? xen_pcpu_down+0x47/0x70 [ 81.583199] [] ? store_online+0x9d/0xb0 [ 81.583210] [] ? kernfs_fop_write+0x12c/0x180 [ 81.583220] [] ? __vfs_write+0x23/0xf0 [ 81.583230] [] ? __sb_start_write+0x42/0xf0 [ 81.583241] [] ? security_file_permission+0x21/0xa0 [ 81.583250] [] ? vfs_write+0xa1/0x1c0 [ 81.583259] [] ? filp_close+0x4f/0x70 [ 81.583268] [] ? SyS_write+0x42/0xb0 [ 81.583277] [] ? __close_fd+0x71/0xb0 [ 81.583287] [] ? system_call_fastpath+0x16/0x75 [ 144.555020] INFO: rcu_sched detected stalls on CPUs/tasks: { 12} (detect= ed by 4, t=3D21007 jiffies, g=3D1691, c=3D1690, q=3D244) [ 144.555046] Task dump for CPU 12: [ 144.555051] bash R running task 0 1347 1094 0x0000= 0008 [ 144.555059] ffffffff00000000 0000000000000000 0000000000000000 ffff8800= 192c2e38 [ 144.555068] ffff8800008472e8 0000000000000002 ffff8800008472e8 ffff8800= 13817858 [ 144.555076] 0000000000000000 00000000000081a4 ffffffff811e8137 ffff8800= 192c2e38 [ 144.555084] Call Trace: [ 144.555096] [] ? notify_change+0x2f7/0x390 [ 144.555105] [] ? do_truncate+0x74/0x90 [ 144.555112] [] ? dput+0x26/0x230 [ 144.555118] [] ? terminate_walk+0x35/0x40 [ 144.555124] [] ? do_last+0x621/0x12c0 [ 144.555164] [] ? xen_pcpu_down+0x47/0x70 [ 144.555172] [] ? store_online+0x9d/0xb0 [ 144.555179] [] ? kernfs_fop_write+0x12c/0x180 [ 144.555186] [] ? __vfs_write+0x23/0xf0 [ 144.555192] [] ? __sb_start_write+0x42/0xf0 [ 144.555200] [] ? security_file_permission+0x21/0xa0 [ 144.555206] [] ? vfs_write+0xa1/0x1c0 [ 144.555212] [] ? filp_close+0x4f/0x70 [ 144.555217] [] ? SyS_write+0x42/0xb0 [ 144.555223] [] ? __close_fd+0x71/0xb0 [ 144.555230] [] ? system_call_fastpath+0x16/0x75 If I revert that patch, the issue goes away. Any ideas?=20 Regards, Dario PS. yes, I'll implement a cpu hotplug/unplug testcase ASAP. :-) --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-76TmArXHlFJxw2YytoM4 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEABECAAYFAlYX79cACgkQk4XaBE3IOsSh0QCgjfeMb/8UxhynnV3953hwMdXe OFQAoKPESf8wdyxpUna++2tyIw27yPM4 =yyk3 -----END PGP SIGNATURE----- --=-76TmArXHlFJxw2YytoM4-- --===============0886449616970044378== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel --===============0886449616970044378==--