Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754731AbbGCKzE (ORCPT ); Fri, 3 Jul 2015 06:55:04 -0400 Received: from sauhun.de ([89.238.76.85]:34654 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752409AbbGCKy4 (ORCPT ); Fri, 3 Jul 2015 06:54:56 -0400 Date: Fri, 3 Jul 2015 12:54:41 +0200 From: Wolfram Sang To: Simon Horman Cc: Thomas Gleixner , Kevin Hilman , Tyler Baker , Borislav Petkov , Geert Uytterhoeven , Magnus Damm , linux-sh@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: Possible regression due to "tick: broadcast: Prevent livelock from event handler" Message-ID: <20150703105441.GF1521@katana> References: <20150703024044.GB24695@verge.net.au> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="SkvwRMAIpAhPCcCJ" Content-Disposition: inline In-Reply-To: <20150703024044.GB24695@verge.net.au> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6131 Lines: 148 --SkvwRMAIpAhPCcCJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Simon, > I have observed what appears to be a regression while testing next-201507= 02 > which seems to be caused by 2951d5c031a3 ("tick: broadcast: Prevent > livelock from event handler"). Does reverting help? I see a similar case with your branch renesas-devel-20150629-v4.1 which does not include both commits. For this branch, if I select CONFIG_NO_HZ_IDLE and *no* CONFIG_HIGH_RES_TIM= ERS, I see the case you described: > input: gpio_keys as /devices/platform/gpio_keys/input/input0 > hctosys: unable to open rtc device (rtc0) >=20 > The boot hangs here. > The next line should be: >=20 > smsc911x 20000000.ethernet eth0: SMSC911x/921x identified at 0xc8880000, = IRQ: 33 There is no OOPS, it just stops here. With CONFIG_HIGH_RES_TIMERS, the system boots to the prompt. Enabling all lockdep features doesn't show anything for the non-working case. However, I get warning for the working case: [ 2.560000] input: gpio_keys as /devices/platform/gpio_keys/input/input0 [ 2.610000] smsc911x 20000000.ethernet eth0: SMSC911x/921x identified at= 0xc8880000, IRQ: 33 [ 5.510000] Sending DHCP requests ., OK [ 5.580000] IP-Config: Got DHCP answer from 192.168.64.1, my address is = 192.168.64.14 [ 5.580000] IP-Config: Complete: [ 5.590000] device=3Deth0, hwaddr=3D00:01:9b:04:03:ce, ipaddr=3D192= =2E168.64.14, mask=3D255.255.255.0, gw=3D192.168.64.1 [ 5.600000] host=3D192.168.64.14, domain=3Dlocal, nis-domain=3D(non= e) [ 5.600000] bootserver=3D192.168.64.1, rootserver=3D192.168.64.1, r= ootpath=3D [ 5.610000] nameserver0=3D192.168.64.1 [ 5.630000] Freeing unused kernel memory: 632K (c0306000 - c03a4000) [ 5.660000] random: init urandom read with 14 bits of entropy available [ 5.820000] ------------[ cut here ]------------ [ 5.820000] WARNING: CPU: 0 PID: 282 at kernel/locking/lockdep.c:3557 ch= eck_flags+0x84/0x1f4() [ 5.820000] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) [ 5.820000] CPU: 0 PID: 282 Comm: rcS Tainted: G W 4.1.0-00= 002-g5b076054611833 #179 [ 5.820000] Hardware name: Generic Emma Mobile EV2 (Flattened Device Tre= e) [ 5.820000] Backtrace:=20 [ 5.820000] [] (dump_backtrace) from [] (show_stack+= 0x18/0x1c) [ 5.820000] r6:c02dcc67 r5:00000009 r4:00000000 r3:00400000 [ 5.820000] [] (show_stack) from [] (dump_stack+0x20= /0x28) [ 5.820000] [] (dump_stack) from [] (warn_slowpath_c= ommon+0x8c/0xb4) [ 5.820000] [] (warn_slowpath_common) from [] (warn_= slowpath_fmt+0x38/0x40) [ 5.820000] r8:c780f470 r7:00000000 r6:00000000 r5:c03b0570 r4:c0b7ec04 [ 5.820000] [] (warn_slowpath_fmt) from [] (check_fl= ags+0x84/0x1f4) [ 5.820000] r3:c02e13d8 r2:c02dceaa [ 5.820000] [] (check_flags) from [] (lock_acquire+0= x4c/0xbc) [ 5.820000] r5:00000000 r4:60000193 [ 5.820000] [] (lock_acquire) from [] (_raw_spin_loc= k+0x34/0x44) [ 5.820000] r9:000a8d5c r8:00000001 r7:c7806000 r6:c780f460 r5:c03b06a0= r4:c780f460 [ 5.820000] [] (_raw_spin_lock) from [] (handle_fast= eoi_irq+0x20/0x11c) [ 5.820000] r4:c780f400 [ 5.820000] [] (handle_fasteoi_irq) from [] (generic= _handle_irq+0x28/0x38) [ 5.820000] r6:00000000 r5:c03b038c r4:00000012 r3:c005a8ac [ 5.820000] [] (generic_handle_irq) from [] (__handl= e_domain_irq+0x88/0xa8) [ 5.820000] r4:00000000 r3:00000026 [ 5.820000] [] (__handle_domain_irq) from [] (gic_ha= ndle_irq+0x40/0x58) [ 5.820000] r8:10c5347d r7:10c5347d r6:c35b1fb0 r5:c03a6304 r4:c8802000= r3:c35b1fb0 [ 5.820000] [] (gic_handle_irq) from [] (__irq_usr+0= x48/0x60) [ 5.820000] Exception stack(0xc35b1fb0 to 0xc35b1ff8) [ 5.820000] 1fa0: 00000061 00000000 = 000ab736 00000066 [ 5.820000] 1fc0: 00000061 000aa1f0 000a8d54 000a8d54 000a8d88 000a8d5c = 000a8cc8 000a8d68 [ 5.820000] 1fe0: 72727272 bef8a528 000398c0 00031334 20000010 ffffffff [ 5.820000] r6:ffffffff r5:20000010 r4:00031334 r3:00000061 [ 5.820000] ---[ end trace cb88537fdc8fa202 ]--- [ 5.820000] possible reason: unannotated irqs-off. [ 5.820000] irq event stamp: 769 [ 5.820000] hardirqs last enabled at (769): [] ret_fast_sysca= ll+0x2c/0x54 [ 5.820000] hardirqs last disabled at (768): [] ret_fast_sysca= ll+0xc/0x54 [ 5.820000] softirqs last enabled at (0): [] copy_process.par= t.65+0x2e8/0x11dc [ 5.820000] softirqs last disabled at (0): [< (null)>] (null) I haven't further researched, but wanted to share this already. All the best, Wolfram# --SkvwRMAIpAhPCcCJ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVlmnxAAoJEBQN5MwUoCm2DNkP/2LPLu4bE6R54jXnJc4+MERe ZJHCcVAyCPvuLXzAIeJIkQGbDTA/VHfPjbFjrE3NI6C3Qf2lXVNi8xCChMomEobt DAd/+SnrAWk9gyJaunC3tCOC3J8Z/R8+7ooypdbu6RKLVK9CkES/nFRiW0sZviLk wHSLn/4G9M7bwB/LubRHxiKDkvNpv/9FavuZgMRcCmWmDDg4VEKYq+8vD5hMZpdE aZ/UvjvJA+Yi4X3GEPimhdndn5PU/UPwtN3D0PPIg2Vy+6I7xBtfvBg3xmppkB2Y KoH4lXSsFLWES/EWJx0COgdt1Re80tR04fSJY8DSMLT8Ivz1V+ETiGE2Z+eLGMQ0 mmpwNHXK7Sn5n4slnARJ1hDL9MGdoP+hG9ahYh4ipvf8/GQH8tNxCFRCPOG8U0BL fbjrfVqqHQHPlVQBWpoBFKjDqxEvNdrrfXxN4iTfiVmEga1hjuG6A0KOiOttrIcz 9MyS0X621dhE+G+1E5YcSQ0Zm+VGF168Mo3zUH4Dtqu9r8IDkstnf/hVTm6Yhv6E /OZhjc2kYI1Si15LgCDksJ4M6JtITgTVUrvOT2hvGnUaIxkrUgsXxLu+r3J4OdAB c4rwpyqTt6Pb1E/NdaHiM48u8w2yKfG5NAqDNjVDd5kecTmlRmEZ13oFVJ3pVSBr vM0jO2plMftsR+sV/lYN =wYW0 -----END PGP SIGNATURE----- --SkvwRMAIpAhPCcCJ-- -- 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/