>-----Original Message----- >From: cpufreq-owner@xxxxxxxxxxxxxxx >[mailto:cpufreq-owner@xxxxxxxxxxxxxxx] On Behalf Of Rusty Russell >Sent: Wednesday, April 15, 2009 4:14 AM >To: Zhang, Yanmin >Cc: LKML; Pallipadi, Venkatesh; Denis Sadykov; >cpufreq@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx >Subject: Re: 2.6.30-rc2 hangs in get_measured_perf on tigerton > >On Wed, 15 Apr 2009 03:31:23 pm Zhang, Yanmin wrote: >> My machine hanged with kernel 2.6.30-rc2 when script read >> /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor. >> >> opps happens in get_measured_perf: >> >> cur.aperf.whole = readin.aperf.whole - >> per_cpu(drv_data, cpu)->saved_aperf; >> >> Because per_cpu(drv_data, cpu)=NULL. >> >> So function get_measured_perf should check if >(per_cpu(drv_data, cpu)==NULL) >> and return 0 if it's NULL. >> >> Other functions have such checking. > >Possibly true, but I can't see that get_measured_perf() ever did. > >Unless there's something subtle with preemption no longer >being disabled >inside that function... > Checking the NULL and returning is not an option. We need to look at average current freq on all CPUs to make correct next freq decision. Also, per_cpu drv_data should be set for all CPUs. I will poke a bit at this and get back... Thanks, Venki >> >> >> --------------sys log------------------ >> >> BUG: unable to handle kernel NULL pointer dereference at >0000000000000020 >> IP: [<ffffffff8021af75>] get_measured_perf+0x4a/0xf9 >> PGD a7dd88067 PUD a7ccf5067 PMD 0 >> Oops: 0000 [#1] SMP >> last sysfs file: >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor >> CPU 0 >> Modules linked in: video output >> Pid: 2091, comm: kondemand/0 Not tainted 2.6.30-rc2 #1 MP Server >> RIP: 0010:[<ffffffff8021af75>] [<ffffffff8021af75>] >get_measured_perf+0x4a/0xf9 >> RSP: 0018:ffff880a7d56de20 EFLAGS: 00010246 >> RAX: 0000000000000000 RBX: 00000046241a42b6 RCX: ffff88004d219000 >> RDX: 000000000000b660 RSI: 0000000000000020 RDI: 0000000000000001 >> RBP: ffff880a7f052000 R08: 00000046241a42b6 R09: ffffffff807639f0 >> R10: 00000000ffffffea R11: ffffffff802207f4 R12: ffff880a7f052000 >> R13: ffff88004d20e460 R14: 0000000000ddd5a6 R15: 0000000000000001 >> FS: 0000000000000000(0000) GS:ffff88004d200000(0000) >knlGS:0000000000000000 >> CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b >> CR2: 0000000000000020 CR3: 0000000a7f1bf000 CR4: 00000000000006e0 >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 >> Process kondemand/0 (pid: 2091, threadinfo ffff880a7d56c000, >task ffff880a7d4d18c0) >> Stack: >> ffff880a7f052078 ffffffff803efd54 00000046241a42b6 000000462ffa9e95 >> 0000000000000001 0000000000000001 00000000ffffffea ffffffff8064f41a >> 0000000000000012 0000000000000012 ffff880a7f052000 ffffffff80650547 >> Call Trace: >> [<ffffffff803efd54>] ? kobject_get+0x12/0x17 >> [<ffffffff8064f41a>] ? __cpufreq_driver_getavg+0x42/0x57 >> [<ffffffff80650547>] ? do_dbs_timer+0x147/0x272 >> [<ffffffff80650400>] ? do_dbs_timer+0x0/0x272 >> [<ffffffff802474ca>] ? worker_thread+0x15b/0x1f5 >> [<ffffffff8024a02c>] ? autoremove_wake_function+0x0/0x2e >> [<ffffffff8024736f>] ? worker_thread+0x0/0x1f5 >> [<ffffffff80249f0d>] ? kthread+0x54/0x83 >> [<ffffffff8020c87a>] ? child_rip+0xa/0x20 >> [<ffffffff80249eb9>] ? kthread+0x0/0x83 >> [<ffffffff8020c870>] ? child_rip+0x0/0x20 >> Code: 99 a6 03 00 31 c9 85 c0 0f 85 c3 00 00 00 89 df 4c 8b >44 24 10 48 c7 c2 60 b6 00 00 48 8b 0c fd e0 30 a5 80 4c 89 c3 >48 8b 04 0a <48> 2b 58 20 48 8b 44 24 18 48 89 1c 24 48 8b 34 >0a 48 2b 46 28 >> RIP [<ffffffff8021af75>] get_measured_perf+0x4a/0xf9 >> RSP <ffff880a7d56de20> >> CR2: 0000000000000020 >> ---[ end trace 2b8fac9a49e19ad4 ]--- >> >> >-- >To unsubscribe from this list: send the line "unsubscribe cpufreq" in >the body of a message to majordomo@xxxxxxxxxxxxxxx >More majordomo info at http://vger.kernel.org/majordomo-info.html >��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
