Re: [PATCH V3 2/4] cpufreq: governor: Implement per policy instancesof governors

From: Viresh Kumar
Date: Tue Mar 26 2013 - 15:32:22 EST

On 26 March 2013 20:50, Jacob Shin <jacob.shin@xxxxxxx> wrote:
> Hi, latest bleeding-edge is spewing this out on boot:
>
> [ 3.585157] ------------[ cut here ]------------
> [ 3.592227] WARNING: at fs/sysfs/dir.c:536 sysfs_add_one+0xc8/0x100()
> [ 3.599521] Hardware name: Dinar
> [ 3.606878] sysfs: cannot create duplicate filename '/devices/system/cpu/cpufreq/ondemand'
> [ 3.614634] Modules linked in:
> [ 3.622382] Pid: 1, comm: swapper/0 Not tainted 3.9.0-rc4+ #7
> [ 3.630305] Call Trace:
> [ 3.638251] [<ffffffff810589cf>] warn_slowpath_common+0x7f/0xc0
> [ 3.646435] [<ffffffff81058ac6>] warn_slowpath_fmt+0x46/0x50
> [ 3.654586] [<ffffffff8133e2f0>] ? strlcat+0x60/0x80
> [ 3.662765] [<ffffffff811fe7d8>] sysfs_add_one+0xc8/0x100
> [ 3.670977] [<ffffffff811fe9cc>] create_dir+0x7c/0xd0
> [ 3.679239] [<ffffffff811fecaf>] sysfs_create_subdir+0x1f/0x30
> [ 3.687601] [<ffffffff812006c4>] internal_create_group+0x64/0x210
> [ 3.696098] [<ffffffff812008a3>] sysfs_create_group+0x13/0x20
> [ 3.704700] [<ffffffff816bf800>] cpufreq_governor_dbs+0x400/0x590
> [ 3.713401] [<ffffffff816bdc37>] od_cpufreq_governor_dbs+0x17/0x20
> [ 3.722191] [<ffffffff816bb437>] __cpufreq_governor+0x47/0xc0
> [ 3.731071] [<ffffffff816bb94d>] __cpufreq_set_policy+0x19d/0x1b0
> [ 3.739968] [<ffffffff816bca89>] cpufreq_add_dev_interface+0x259/0x2b0
> [ 3.748960] [<ffffffff813cdce6>] ? acpi_processor_get_performance_info+0x21c/0x452
> [ 3.758099] [<ffffffff816bc210>] ? cpufreq_update_policy+0x130/0x130
> [ 3.767366] [<ffffffff816bce90>] cpufreq_add_dev+0x3b0/0x4d0
> [ 3.776659] [<ffffffff821579d4>] ? cpufreq_gov_dbs_init+0x12/0x12
> [ 3.785985] [<ffffffff814e6a39>] subsys_interface_register+0x89/0xd0
> [ 3.795452] [<ffffffff816baf5e>] cpufreq_register_driver+0x8e/0x180
> [ 3.804919] [<ffffffff82157aca>] acpi_cpufreq_init+0xf6/0x1f8
> [ 3.814360] [<ffffffff814f5030>] ? set_trace_device+0x80/0x80
> [ 3.823558] [<ffffffff8100206f>] do_one_initcall+0x3f/0x170
> [ 3.832476] [<ffffffff8211b00a>] kernel_init_freeable+0x13e/0x1cd
> [ 3.841131] [<ffffffff8211a88e>] ? do_early_param+0x86/0x86
> [ 3.849506] [<ffffffff817f4c20>] ? rest_init+0x80/0x80
> [ 3.857557] [<ffffffff817f4c2e>] kernel_init+0xe/0xf0
> [ 3.865260] [<ffffffff8181edec>] ret_from_fork+0x7c/0xb0
> [ 3.872886] [<ffffffff817f4c20>] ? rest_init+0x80/0x80
> [ 3.880456] ---[ end trace 1a5c6247c6d9b0ac ]---
> [ 3.888201] ------------[ cut here ]------------
>
> This warning is repeated for number of cpus - 1 times.
>
> And when I do:
>
> $ cat /sys/devices/system/cpu/cpufreq/ondemand/up_threshold
>
> [ 489.103388] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> [ 489.112064] IP: [<ffffffff816be02c>] show_up_threshold+0x1c/0x30
> [ 489.120511] PGD a285e6067 PUD a27085067 PMD 0
> [ 489.128690] Oops: 0000 [#1] SMP
> [ 489.136521] Modules linked in:
> [ 489.144134] CPU 15
> [ 489.144229] Pid: 1565, comm: cat Tainted: G W 3.9.0-rc4+ #7 AMD Dinar/Dinar
> [ 489.159654] RIP: 0010:[<ffffffff816be02c>] [<ffffffff816be02c>] show_up_threshold+0x1c/0x30
> [ 489.167864] RSP: 0018:ffff880423859e88 EFLAGS: 00010246
> [ 489.176043] RAX: 0000000000000000 RBX: ffff880a271188c0 RCX: ffffffff81a41810
> [ 489.184372] RDX: 0000000000000000 RSI: ffffffff81e02dae RDI: ffffffff820d7860
> [ 489.184373] RBP: ffff880423859e88 R08: ffffea0028b6df80 R09: 00000000001f05b8
> [ 489.184374] R10: 0000000000001b97 R11: 0000000000000246 R12: ffff880423859f50
> [ 489.184374] R13: 0000000000008000 R14: ffff880a271188a0 R15: ffff8804251aa070
> [ 489.184377] FS: 00007f3278b31700(0000) GS:ffff880a2fcc0000(0000) knlGS:0000000000000000
> [ 489.184378] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 489.184378] CR2: 0000000000000010 CR3: 0000000a2db82000 CR4: 00000000000407e0
> [ 489.184380] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 489.184381] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 489.184382] Process cat (pid: 1565, threadinfo ffff880423858000, task ffff880424805c00)
> [ 489.184382] Stack:
> [ 489.184389] ffff880423859e98 ffffffff8133814f ffff880423859ef8 ffffffff811fd62a
> [ 489.184394] 000000002bf67be2 ffff8808260b7a80 ffffffff81a41810 00000000012c8000
> [ 489.184399] ffff880423859ef8 0000000000008000 00000000012c8000 ffff880423859f50
> [ 489.184400] Call Trace:
> [ 489.184406] [<ffffffff8133814f>] kobj_attr_show+0xf/0x30
> [ 489.184411] [<ffffffff811fd62a>] sysfs_read_file+0xaa/0x190
> [ 489.184415] [<ffffffff81187e30>] vfs_read+0xb0/0x180
> [ 489.184418] [<ffffffff81187f52>] sys_read+0x52/0xa0
> [ 489.184422] [<ffffffff8181a7fe>] ? do_page_fault+0xe/0x10
> [ 489.184426] [<ffffffff8181ee99>] system_call_fastpath+0x16/0x1b
> [ 489.184441] Code: 52 08 e8 78 2c c8 ff 5d 48 98 c3 0f 1f 40 00 66 66 66 66 90 55 48 8b 57 70 48 89 f0 48 89 c7 48 c7 c6 ae 2d e0 81 31 c0 48 89 e5 <48> 8b 52 10 8b 52 0c e8 48 2c c8 ff 5d 48 98 c3 0f 1f 40 00 66
> [ 489.184443] RIP [<ffffffff816be02c>] show_up_threshold+0x1c/0x30
> [ 489.184443] RSP <ffff880423859e88>
> [ 489.184444] CR2: 0000000000000010
> [ 489.184507] ---[ end trace 1a5c6247c6d9b0c3 ]---
>
> Any ideas?

Yes, i believe i have enough idea about it :)

There are two kind of systems i know:
1 - Single group of cpus controlled by a single clock line,
i.e. only one policy instance at any time
2 - multipolicy systems where we have more than one group of cpus
and every group have one clock line.

For the second case also there are two cases:
2.1 - support have_multiple_policies (i.e. have separate instance of governor
for each policy struct)
2.2 - doesn't support have_multiple_policies

The last one (2.2) is broken with my patch and attached is the fix. I
have tested
it on my Lenovo Thinkpad which is more like 2.2 case.

cat of cpufreq/ondemand/** is still broken and i am too tired of
fixing it now...
Its already midnight here 01:01 AM.

--
viresh

Attachment: 0001-fixup-cpufreq-governor-Implement-per-policy-instance.patch
Description: Binary data