On Thursday, May 05, 2016 01:05:41 PM Wanpeng Li wrote: > 2016-05-03 23:10 GMT+08:00 Rafael J. Wysocki <r...@rjwysocki.net>: > > On Tuesday, May 03, 2016 03:53:12 PM Rafael J. Wysocki wrote: > >> On Tuesday, May 03, 2016 03:22:24 PM Rafael J. Wysocki wrote: > >> > On Tue, May 3, 2016 at 2:58 PM, Rafael J. Wysocki <raf...@kernel.org> > >> > wrote: > >> > > On Tue, May 3, 2016 at 2:54 PM, Rafael J. Wysocki <raf...@kernel.org> > >> > > wrote: > >> > >> On Tue, May 3, 2016 at 2:15 PM, Rafael J. Wysocki <raf...@kernel.org> > >> > >> wrote: > >> > >>> On Tue, May 3, 2016 at 10:32 AM, Peter Zijlstra > >> > >>> <pet...@infradead.org> wrote: > >> > >>>> On Tue, May 03, 2016 at 09:10:51AM +0800, kernel test robot wrote: > >> > >>>>> FYI, we noticed the following commit: > >> > >>>>> > >> > >>>>> https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git > >> > >>>>> sched/core > >> > >>>>> commit 41e0d37f7ac81297c07ba311e4ad39465b8c8295 ("sched/fair: Do > >> > >>>>> not call cpufreq hook unless util changed") > >> > >>>> > >> > >>>> > >> > >>>>> [ 14.860950] Freeing unused kernel memory: 260K > >> > >>>>> (ffff88103edbf000 - ffff88103ee00000) > >> > >>>>> [ 14.873013] systemd[1]: RTC configured in localtime, applying > >> > >>>>> delta of 480 minutes to system time. > >> > >>>>> [ 14.884474] random: systemd urandom read with 5 bits of entropy > >> > >>>>> available > >> > >>>>> [ 14.903975] divide error: 0000 [#1] SMP > >> > >>>>> [ 14.908375] Modules linked in: > >> > >>>>> [ 14.911793] CPU: 39 PID: 1 Comm: systemd Not tainted > >> > >>>>> 4.6.0-rc4-00016-g41e0d37 #1 > >> > >>>>> [ 14.920051] Hardware name: Intel Corporation S2600WP/S2600WP, > >> > >>>>> BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013 > >> > >>>>> [ 14.931509] task: ffff8810101d8000 ti: ffff88081ab20000 > >> > >>>>> task.ti: ffff88081ab20000 > >> > >>>>> [ 14.939862] RIP: 0010:[<ffffffff8176ad32>] > >> > >>>>> [<ffffffff8176ad32>] intel_pstate_get+0x32/0x40 > >> > >>>>> [ 14.949202] RSP: 0018:ffff88081ab23d70 EFLAGS: 00010006 > >> > >>>>> [ 14.955129] RAX: 0000000000000000 RBX: 0000000000000024 RCX: > >> > >>>>> ffff8808091e0300 > >> > >>>>> [ 14.963094] RDX: 0000000000000000 RSI: 0000000000000100 RDI: > >> > >>>>> 0000000000000024 > >> > >>>>> [ 14.971057] RBP: ffff88081ab23d88 R08: 0000000000001000 R09: > >> > >>>>> 00000000096a1000 > >> > >>>>> [ 14.979022] R10: 0000000000ffff10 R11: 000000000000000f R12: > >> > >>>>> 0000000000000202 > >> > >>>>> [ 14.986984] R13: ffff88101390a040 R14: ffff88100e48e180 R15: > >> > >>>>> ffff88101390a040 > >> > >>>>> [ 14.994950] FS: 00007f66fe117880(0000) > >> > >>>>> GS:ffff8810139c0000(0000) knlGS:0000000000000000 > >> > >>>>> [ 15.003982] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >> > >>>>> [ 15.010393] CR2: 000055f78b760098 CR3: 000000103d759000 CR4: > >> > >>>>> 00000000001406e0 > >> > >>>>> [ 15.018359] Stack: > >> > >>>>> [ 15.020602] ffffffff81764dad 0000000000000024 ffff88100e48e180 > >> > >>>>> ffff88081ab23dc8 > >> > >>>>> [ 15.028899] ffffffff81040267 ffff88101390a0ac 0000000000000340 > >> > >>>>> ffff88081ab23f20 > >> > >>>>> [ 15.037197] ffff88103cd7c400 ffff88100e48e180 ffff88101390a040 > >> > >>>>> ffff88081ab23e30 > >> > >>>>> [ 15.045493] Call Trace: > >> > >>>>> [ 15.048223] [<ffffffff81764dad>] ? cpufreq_quick_get+0x3d/0x90 > >> > >>>>> [ 15.054832] [<ffffffff81040267>] show_cpuinfo+0x3c7/0x410 > >> > >>>>> [ 15.060956] [<ffffffff8121f5c4>] seq_read+0x2c4/0x3a0 > >> > >>>>> [ 15.066685] [<ffffffff81266ea8>] proc_reg_read+0x48/0x70 > >> > >>>>> [ 15.072713] [<ffffffff811f9d58>] __vfs_read+0x28/0xd0 > >> > >>>>> [ 15.078451] [<ffffffff813bab63>] ? > >> > >>>>> security_file_permission+0xa3/0xc0 > >> > >>>>> [ 15.085737] [<ffffffff811faa97>] ? rw_verify_area+0x57/0xd0 > >> > >>>>> [ 15.092054] [<ffffffff811fab96>] vfs_read+0x86/0x130 > >> > >>>>> [ 15.097691] [<ffffffff811fbf96>] SyS_read+0x46/0xa0 > >> > >>>>> [ 15.103234] [<ffffffff818f71b2>] > >> > >>>>> entry_SYSCALL_64_fastpath+0x1a/0xa4 > >> > >>>>> [ 15.110421] Code: 05 dc 1b c3 00 89 ff 55 48 89 e5 48 8b 0c f8 > >> > >>>>> 48 85 c9 74 1f 48 63 51 1c 48 63 41 20 5d 48 0f af c2 31 d2 48 0f > >> > >>>>> af 81 88 00 00 00 <48> f7 b1 90 00 00 00 c3 31 c0 5d c3 66 90 0f > >> > >>>>> 1f 44 00 00 8b 77 > >> > >>>>> [ 15.132161] RIP [<ffffffff8176ad32>] intel_pstate_get+0x32/0x40 > >> > >>>>> [ 15.138875] RSP <ffff88081ab23d70> > >> > >>>>> [ 15.142770] ---[ end trace e5d5a8bedf5502e1 ]--- > >> > >>>>> [ 15.149323] Kernel panic - not syncing: Fatal exception > >> > >>>>> > >> > >>>> > >> > >>>> That's intel_pstate.c:get_avg_frequency(), which assumes mperf != > >> > >>>> 0. It > >> > >>>> being 0 seems to suggest intel_pstate_sample() hasn't been called > >> > >>>> yet or > >> > >>>> so. > >> > >>> > >> > >>> Well, what's the tree based on? > >> > >>> > >> > >>> The mainline does this: > >> > >>> > >> > >>> bool sample_taken = intel_pstate_sample(cpu, time); > >> > >>> > >> > >>> if (sample_taken && !hwp_active) > >> > >>> intel_pstate_adjust_busy_pstate(cpu); > >> > >>> > >> > >>> and (the mainline version of) intel_pstate_sample() returns false > >> > >>> when > >> > >>> it is called for the first time after setting the update_util hook. > >> > >> > >> > >> If that helps, I can expose my pm-cpufreq-fixes branch to pull from. > >> > >> It contains all cpufreq material that went into the Linus' tree to > >> > >> date and is based on 4.5-rc3. > >> > > > >> > > In fact, it is exposed already: > >> > > > >> > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \ > >> > > pm-cpufreq-fixes > >> > > > >> > > and the top-most commit is 1becf03545a0859ceaaf9e8c2d9861882a71cb01 > >> > > (cpufreq: intel_pstate: Fix processing for turbo activation ratio). > >> > > >> > Ah, that will fail as well. > >> > > >> > The problem is that intel_pstate_get() can be called before we take > >> > the first sample. > >> > > >> > I need to think about how to fix that. > >> > >> Maybe something like the below (untested, but builds). > >> > >> It will make intel_pstate_get() return 0 until avg_frequency gets populated > >> which is actually OK. > > > > The previous one would break the HWP case, so below is a new one (still > > untested). > > I can reproduce the bug and your patch fix it. > > Tested-by: Wanpeng Li <wanpeng...@hotmail.com>
Thanks! Please also try this one: https://patchwork.kernel.org/patch/9012861/ which is the final fix for this bug.
