On Fri, Mar 30, 2007 at 12:09:03PM +0400, Alexey Dobriyan wrote: > On Thu, Mar 22, 2007 at 06:02:01PM +0100, Mattia Dongili wrote: > > On Wed, Mar 21, 2007 at 08:10:42PM -0800, Andrew Morton wrote: > > > I ain't picky, but as a short-term thing it'd be kinda nice if it didn't > > > oops the kernel. > > > > There are other symptoms to this same bug: > > > > 1. unload p4-clockmod: /sys/.../cpu0/cpufreq is removed all together > > 2. load p4-clockmod: /sys/.../cpu0/cpufreq appears but no 'stats' subdir > > (yes, cpufreq_stats is loaded) > > 3. rmmod cpufreq_stats: Ooops! > > > > Call Trace: > > [<c0183f5b>] remove_dir+0x33/0xc4 > > [<c0184fca>] remove_files+0x1a/0x28 > > [<c018503b>] sysfs_remove_group+0x63/0x71 > > [<f898c38d>] cpufreq_stat_cpu_callback+0x51/0x8a [cpufreq_stats] > > [<f898c477>] cpufreq_stats_exit+0x47/0x4b [cpufreq_stats] > > [<c012f145>] sys_delete_module+0x190/0x1b7 > > [<c0140073>] do_wp_page+0x231/0x3e7 > > [<c0102e17>] syscall_call+0x7/0xb > > > > The problem is cpufreq_stats doesn't know when a cpufreq driver is > > removed and doesn't cleanup. I guess this affects any setup with > > cpufreq_stats. > > The attached patch seems to solve both symptoms and yes... it's quite > > invasive as it introduce one more cpufreq policy notification (REMOVED). > > > > BTW: the patch is against .21-rc4-mm1 but applies with some fuzz to > > 2.6.20 too > > Also, it doesn't work.
hmmm... odd. I did test that case. Also, using .21-rc5-mm3 (which has that patch applied) and acpi-cpufreq (I don't have that P4 handy now) I actually hit a WARN_ON in kref_get(), but no oops: # rmmod acpi-cpufreq [ 1839.895632] acpi-cpufreq: acpi_cpufreq_exit [ 1839.895637] cpufreq-core: unregistering driver acpi-cpufreq [ 1839.895642] cpufreq-core: unregistering CPU 0 [ 1839.895649] cpufreq-core: __cpufreq_governor for CPU 0, event 2 [ 1839.895661] cpufreq-stats: removing tables [ 1839.895714] cpufreq-core: last reference is dropped [ 1839.895716] cpufreq-core: waiting for dropping of refcount [ 1839.895718] cpufreq-core: wait complete [ 1839.895720] acpi-cpufreq: acpi_cpufreq_cpu_exit [ 1839.895723] freq-table: clearing show_table for cpu 0 [ 1839.895726] cpufreq-core: unregistering CPU 1 [ 1839.895728] cpufreq-core: __cpufreq_governor for CPU 1, event 2 [ 1839.895731] cpufreq-stats: removing tables <------- dprintk on CPUFREQ_REMOVE [ 1839.895741] cpufreq-core: last reference is dropped [ 1839.895744] cpufreq-core: waiting for dropping of refcount [ 1839.895746] cpufreq-core: wait complete [ 1839.895747] acpi-cpufreq: acpi_cpufreq_cpu_exit [ 1839.895749] freq-table: clearing show_table for cpu 1 # cat time_in_state [ 1853.932509] BUG: at lib/kref.c:32 kref_get() [ 1853.932567] [<c0104b7a>] show_trace_log_lvl+0x1a/0x30 [ 1853.932676] [<c0105705>] show_trace+0x12/0x14 [ 1853.932778] [<c010575e>] dump_stack+0x16/0x18 [ 1853.932880] [<c01dcfba>] kref_get+0x37/0x40 [ 1853.932986] [<c01dc415>] kobject_get+0x15/0x1b [ 1853.933087] [<c019ff0b>] sysfs_open_file+0x40/0x209 [ 1853.933189] [<c01693bc>] __dentry_open+0xc2/0x179 [ 1853.933293] [<c01694f5>] nameidata_to_filp+0x27/0x38 [ 1853.933395] [<c0169539>] do_filp_open+0x33/0x3b [ 1853.933498] [<c0169584>] do_sys_open+0x43/0xc7 [ 1853.933600] [<c0169640>] sys_open+0x1c/0x1e [ 1853.933700] [<c0103d24>] sysenter_past_esp+0x5d/0x81 [ 1853.933799] ======================= [ 1853.934330] cpufreq-core: last reference is dropped -- mattia :wq! - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
