| Message ID | 20160204062439.GZ3469@vireshk (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 04-02-16, 11:54, Viresh Kumar wrote: > From the code I still failed to understand this since sometime back > and I something just caught my eyes and the 6th patch needs this > fixup: > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 7bc8a5ed97e5..ac3348ecde7b 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -1351,7 +1351,7 @@ static void cpufreq_offline(unsigned int cpu) > pr_err("%s: Failed to start governor\n", __func__); > } > > - return; > + goto unlock; > } > > if (cpufreq_driver->stop_cpu) > @@ -1373,6 +1373,8 @@ static void cpufreq_offline(unsigned int cpu) > cpufreq_driver->exit(policy); > policy->freq_table = NULL; > } > + > +unlock: > up_write(&policy->rwsem); > } > > I tried the basic tests using './runme' and they aren't reporting the > same lockdep now. And yes, your lockdep occurred on my exynos board as > well :) > > I have re-pushed my patches again to the same branch. All 7 look fine > to me now :) FWIW, Juri has reported on IRC that the above diff fixed the lockdep he reported yesterday and all the 7 patches are working fine on his test machine, Juno.
Hi, > > FWIW, Juri has reported on IRC that the above diff fixed the lockdep > he reported yesterday and all the 7 patches are working fine on his > test machine, Juno. > I could see the previous lockdep warnings on pm/next and on top of patch[4]. On Patch[5-7] I see the below lockdep trace on running './runme' on a Power8 box. [ 710.332841] ====================================================== [ 710.332911] [ INFO: possible circular locking dependency detected ] [ 710.332969] 4.5.0-rc2-sgb+ #104 Not tainted [ 710.333004] ------------------------------------------------------- [ 710.333060] runme.sh/2476 is trying to acquire lock: [ 710.333107] (s_active#91){++++.+}, at: [<c000000000407db8>] kernfs_remove+0x48/0x70 [ 710.333215] but task is already holding lock: [ 710.333272] (od_dbs_cdata.mutex){+.+.+.}, at: [<c000000000ad7434>] cpufreq_governor_dbs+0x64/0x7e0 [ 710.333388] which lock already depends on the new lock. [ 710.333456] the existing dependency chain (in reverse order) is: [ 710.333523] -> #2 (od_dbs_cdata.mutex){+.+.+.}: [ 710.333604] [<c000000000d48450>] mutex_lock_nested+0x90/0x590 [ 710.333673] [<c000000000ad5698>] update_sampling_rate+0x88/0x1c0 [ 710.333741] [<c000000000ad5830>] store_sampling_rate+0x60/0xa0 [ 710.333809] [<c000000000ad6990>] governor_store+0x80/0xc0 [ 710.333865] [<c00000000040a8a4>] sysfs_kf_write+0x94/0xc0 [ 710.333923] [<c0000000004094a8>] kernfs_fop_write+0x188/0x1f0 [ 710.333991] [<c000000000347b8c>] __vfs_write+0x6c/0x180 [ 710.334049] [<c0000000003490a0>] vfs_write+0xc0/0x200 [ 710.334107] [<c00000000034a3cc>] SyS_write+0x6c/0x110 [ 710.334163] [<c00000000000926c>] system_call+0x38/0xd0 [ 710.334222] -> #1 (&dbs_data->mutex){+.+...}: [ 710.334290] [<c000000000d48450>] mutex_lock_nested+0x90/0x590 [ 710.334358] [<c000000000ad6960>] governor_store+0x50/0xc0 [ 710.334415] [<c00000000040a8a4>] sysfs_kf_write+0x94/0xc0 [ 710.334471] [<c0000000004094a8>] kernfs_fop_write+0x188/0x1f0 [ 710.334539] [<c000000000347b8c>] __vfs_write+0x6c/0x180 [ 710.334596] [<c0000000003490a0>] vfs_write+0xc0/0x200 [ 710.334653] [<c00000000034a3cc>] SyS_write+0x6c/0x110 [ 710.334710] [<c00000000000926c>] system_call+0x38/0xd0 [ 710.334767] -> #0 (s_active#91){++++.+}: [ 710.334847] [<c00000000015f318>] lock_acquire+0xd8/0x1a0 [ 710.334905] [<c0000000004065f4>] __kernfs_remove+0x344/0x410 [ 710.334973] [<c000000000407db8>] kernfs_remove+0x48/0x70 [ 710.335030] [<c00000000040b868>] sysfs_remove_dir+0x78/0xd0 [ 710.335098] [<c0000000005eccec>] kobject_del+0x2c/0x80 [ 710.335156] [<c0000000005ec9e8>] kobject_release+0xa8/0x250 [ 710.335224] [<c000000000ad7ac8>] cpufreq_governor_dbs+0x6f8/0x7e0 [ 710.335292] [<c000000000ad4a7c>] od_cpufreq_governor_dbs+0x3c/0x60 [ 710.335361] [<c000000000acf7c4>] __cpufreq_governor+0x164/0x300 [ 710.335429] [<c000000000ad0600>] cpufreq_set_policy+0x3b0/0x450 [ 710.335497] [<c000000000ad117c>] store_scaling_governor+0x8c/0xf0 [ 710.335565] [<c000000000aced34>] store+0xb4/0x110 [ 710.335622] [<c00000000040a8a4>] sysfs_kf_write+0x94/0xc0 [ 710.335679] [<c0000000004094a8>] kernfs_fop_write+0x188/0x1f0 [ 710.335747] [<c000000000347b8c>] __vfs_write+0x6c/0x180 [ 710.335803] [<c0000000003490a0>] vfs_write+0xc0/0x200 [ 710.335861] [<c00000000034a3cc>] SyS_write+0x6c/0x110 [ 710.335918] [<c00000000000926c>] system_call+0x38/0xd0 [ 710.335993] other info that might help us debug this: [ 710.336130] Chain exists of: s_active#91 --> &dbs_data->mutex --> od_dbs_cdata.mutex [ 710.336376] Possible unsafe locking scenario: [ 710.336488] CPU0 CPU1 [ 710.336577] ---- ---- [ 710.336666] lock(od_dbs_cdata.mutex); [ 710.336778] lock(&dbs_data->mutex); [ 710.336911] lock(od_dbs_cdata.mutex); [ 710.337064] lock(s_active#91); [ 710.337176] *** DEADLOCK *** [ 710.337289] 6 locks held by runme.sh/2476: [ 710.337355] #0: (sb_writers#6){.+.+.+}, at: [<c00000000034cf10>] __sb_start_write+0x120/0x150 [ 710.337600] #1: (&of->mutex){+.+.+.}, at: [<c00000000040939c>] kernfs_fop_write+0x7c/0x1f0 [ 710.337824] #2: (s_active#82){.+.+.+}, at: [<c0000000004093a8>] kernfs_fop_write+0x88/0x1f0 [ 710.338070] #3: (cpu_hotplug.lock){++++++}, at: [<c0000000000e06d8>] get_online_cpus+0x48/0xc0 [ 710.338276] #4: (&policy->rwsem){+++++.}, at: [<c000000000aced04>] store+0x84/0x110 [ 710.338476] #5: (od_dbs_cdata.mutex){+.+.+.}, at: [<c000000000ad7434>] cpufreq_governor_dbs+0x64/0x7e0 [ 710.338722] stack backtrace: [ 710.338813] CPU: 0 PID: 2476 Comm: runme.sh Not tainted 4.5.0-rc2-sgb+ #104 [ 710.338929] Call Trace: [ 710.338978] [c000005fd40eaec0] [c000000000d563d0] dump_stack+0x90/0xbc (unreliable) [ 710.339138] [c000005fd40eaef0] [c00000000015884c] print_circular_bug+0x28c/0x3e0 [ 710.339295] [c000005fd40eaf90] [c00000000015ed88] __lock_acquire+0x2278/0x22d0 [ 710.339455] [c000005fd40eb120] [c00000000015f318] lock_acquire+0xd8/0x1a0 [ 710.339589] [c000005fd40eb1e0] [c0000000004065f4] __kernfs_remove+0x344/0x410 [ 710.339724] [c000005fd40eb2e0] [c000000000407db8] kernfs_remove+0x48/0x70 [ 710.339859] [c000005fd40eb310] [c00000000040b868] sysfs_remove_dir+0x78/0xd0 [ 710.339993] [c000005fd40eb350] [c0000000005eccec] kobject_del+0x2c/0x80 [ 710.340128] [c000005fd40eb380] [c0000000005ec9e8] kobject_release+0xa8/0x250 [ 710.340265] [c000005fd40eb410] [c000000000ad7ac8] cpufreq_governor_dbs+0x6f8/0x7e0 [ 710.340423] [c000005fd40eb4c0] [c000000000ad4a7c] od_cpufreq_governor_dbs+0x3c/0x60 [ 710.340561] [c000005fd40eb500] [c000000000acf7c4] __cpufreq_governor+0x164/0x300 [ 710.340639] [c000005fd40eb580] [c000000000ad0600] cpufreq_set_policy+0x3b0/0x450 [ 710.340719] [c000005fd40eb610] [c000000000ad117c] store_scaling_governor+0x8c/0xf0 [ 710.340797] [c000005fd40ebc10] [c000000000aced34] store+0xb4/0x110 [ 710.340866] [c000005fd40ebc60] [c00000000040a8a4] sysfs_kf_write+0x94/0xc0 [ 710.340934] [c000005fd40ebca0] [c0000000004094a8] kernfs_fop_write+0x188/0x1f0 [ 710.341013] [c000005fd40ebcf0] [c000000000347b8c] __vfs_write+0x6c/0x180 [ 710.341081] [c000005fd40ebd90] [c0000000003490a0] vfs_write+0xc0/0x200 [ 710.341151] [c000005fd40ebde0] [c00000000034a3cc] SyS_write+0x6c/0x110 [ 710.341219] [c000005fd40ebe30] [c00000000000926c] system_call+0x38/0xd0 Thanks and Regards, Shilpa -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05-02-16, 02:20, Shilpasri G Bhat wrote: > I could see the previous lockdep warnings on pm/next and on top of patch[4]. > On Patch[5-7] I see the below lockdep trace on running './runme' on a Power8 box. > [ 710.336130] Chain exists of: > s_active#91 --> &dbs_data->mutex --> od_dbs_cdata.mutex > > [ 710.336376] Possible unsafe locking scenario: > > [ 710.336488] CPU0 CPU1 > [ 710.336577] ---- ---- > [ 710.336666] lock(od_dbs_cdata.mutex); > [ 710.336778] lock(&dbs_data->mutex); > [ 710.336911] lock(od_dbs_cdata.mutex); > [ 710.337064] lock(s_active#91); > [ 710.337176] This is the same lockdep, just that we have added another mutex (dbs_data->mutex) to it. Have you tried if all the lockdeps go away with the 8th patch that I provided yesterday ?
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 7bc8a5ed97e5..ac3348ecde7b 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1351,7 +1351,7 @@ static void cpufreq_offline(unsigned int cpu) pr_err("%s: Failed to start governor\n", __func__); } - return; + goto unlock; } if (cpufreq_driver->stop_cpu) @@ -1373,6 +1373,8 @@ static void cpufreq_offline(unsigned int cpu) cpufreq_driver->exit(policy); policy->freq_table = NULL; } + +unlock: up_write(&policy->rwsem); }