user/sven/linux.git/kernel/time, branch v3.12.27

timer: Fix lock inversion between hrtimer_bases.lock and scheduler locks

2014-08-19T12:23:37Z

commit 504d58745c9ca28d33572e2d8a9990b43e06075d upstream. clockevents_increase_min_delta() calls printk() from under hrtimer_bases.lock. That causes lock inversion on scheduler locks because printk() can call into the scheduler. Lockdep puts it as: ====================================================== [ INFO: possible circular locking dependency detected ] 3.15.0-rc8-06195-g939f04b #2 Not tainted ------------------------------------------------------- trinity-main/74 is trying to acquire lock: (&port_lock_key){-.....}, at: [<811c60be>] serial8250_console_write+0x8c/0x10c but task is already holding lock: (hrtimer_bases.lock){-.-...}, at: [<8103caeb>] hrtimer_try_to_cancel+0x13/0x66 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (hrtimer_bases.lock){-.-...}: [<8104a942>] lock_acquire+0x92/0x101 [<8142f11d>] _raw_spin_lock_irqsave+0x2e/0x3e [<8103c918>] __hrtimer_start_range_ns+0x1c/0x197 [<8107ec20>] perf_swevent_start_hrtimer.part.41+0x7a/0x85 [<81080792>] task_clock_event_start+0x3a/0x3f [<810807a4>] task_clock_event_add+0xd/0x14 [<8108259a>] event_sched_in+0xb6/0x17a [<810826a2>] group_sched_in+0x44/0x122 [<81082885>] ctx_sched_in.isra.67+0x105/0x11f [<810828e6>] perf_event_sched_in.isra.70+0x47/0x4b [<81082bf6>] __perf_install_in_context+0x8b/0xa3 [<8107eb8e>] remote_function+0x12/0x2a [<8105f5af>] smp_call_function_single+0x2d/0x53 [<8107e17d>] task_function_call+0x30/0x36 [<8107fb82>] perf_install_in_context+0x87/0xbb [<810852c9>] SYSC_perf_event_open+0x5c6/0x701 [<810856f9>] SyS_perf_event_open+0x17/0x19 [<8142f8ee>] syscall_call+0x7/0xb -> #4 (&ctx->lock){......}: [<8104a942>] lock_acquire+0x92/0x101 [<8142f04c>] _raw_spin_lock+0x21/0x30 [<81081df3>] __perf_event_task_sched_out+0x1dc/0x34f [<8142cacc>] __schedule+0x4c6/0x4cb [<8142cae0>] schedule+0xf/0x11 [<8142f9a6>] work_resched+0x5/0x30 -> #3 (&rq->lock){-.-.-.}: [<8104a942>] lock_acquire+0x92/0x101 [<8142f04c>] _raw_spin_lock+0x21/0x30 [<81040873>] __task_rq_lock+0x33/0x3a [<8104184c>] wake_up_new_task+0x25/0xc2 [<8102474b>] do_fork+0x15c/0x2a0 [<810248a9>] kernel_thread+0x1a/0x1f [<814232a2>] rest_init+0x1a/0x10e [<817af949>] start_kernel+0x303/0x308 [<817af2ab>] i386_start_kernel+0x79/0x7d -> #2 (&p->pi_lock){-.-...}: [<8104a942>] lock_acquire+0x92/0x101 [<8142f11d>] _raw_spin_lock_irqsave+0x2e/0x3e [<810413dd>] try_to_wake_up+0x1d/0xd6 [<810414cd>] default_wake_function+0xb/0xd [<810461f3>] __wake_up_common+0x39/0x59 [<81046346>] __wake_up+0x29/0x3b [<811b8733>] tty_wakeup+0x49/0x51 [<811c3568>] uart_write_wakeup+0x17/0x19 [<811c5dc1>] serial8250_tx_chars+0xbc/0xfb [<811c5f28>] serial8250_handle_irq+0x54/0x6a [<811c5f57>] serial8250_default_handle_irq+0x19/0x1c [<811c56d8>] serial8250_interrupt+0x38/0x9e [<810510e7>] handle_irq_event_percpu+0x5f/0x1e2 [<81051296>] handle_irq_event+0x2c/0x43 [<81052cee>] handle_level_irq+0x57/0x80 [<81002a72>] handle_irq+0x46/0x5c [<810027df>] do_IRQ+0x32/0x89 [<8143036e>] common_interrupt+0x2e/0x33 [<8142f23c>] _raw_spin_unlock_irqrestore+0x3f/0x49 [<811c25a4>] uart_start+0x2d/0x32 [<811c2c04>] uart_write+0xc7/0xd6 [<811bc6f6>] n_tty_write+0xb8/0x35e [<811b9beb>] tty_write+0x163/0x1e4 [<811b9cd9>] redirected_tty_write+0x6d/0x75 [<810b6ed6>] vfs_write+0x75/0xb0 [<810b7265>] SyS_write+0x44/0x77 [<8142f8ee>] syscall_call+0x7/0xb -> #1 (&tty->write_wait){-.....}: [<8104a942>] lock_acquire+0x92/0x101 [<8142f11d>] _raw_spin_lock_irqsave+0x2e/0x3e [<81046332>] __wake_up+0x15/0x3b [<811b8733>] tty_wakeup+0x49/0x51 [<811c3568>] uart_write_wakeup+0x17/0x19 [<811c5dc1>] serial8250_tx_chars+0xbc/0xfb [<811c5f28>] serial8250_handle_irq+0x54/0x6a [<811c5f57>] serial8250_default_handle_irq+0x19/0x1c [<811c56d8>] serial8250_interrupt+0x38/0x9e [<810510e7>] handle_irq_event_percpu+0x5f/0x1e2 [<81051296>] handle_irq_event+0x2c/0x43 [<81052cee>] handle_level_irq+0x57/0x80 [<81002a72>] handle_irq+0x46/0x5c [<810027df>] do_IRQ+0x32/0x89 [<8143036e>] common_interrupt+0x2e/0x33 [<8142f23c>] _raw_spin_unlock_irqrestore+0x3f/0x49 [<811c25a4>] uart_start+0x2d/0x32 [<811c2c04>] uart_write+0xc7/0xd6 [<811bc6f6>] n_tty_write+0xb8/0x35e [<811b9beb>] tty_write+0x163/0x1e4 [<811b9cd9>] redirected_tty_write+0x6d/0x75 [<810b6ed6>] vfs_write+0x75/0xb0 [<810b7265>] SyS_write+0x44/0x77 [<8142f8ee>] syscall_call+0x7/0xb -> #0 (&port_lock_key){-.....}: [<8104a62d>] __lock_acquire+0x9ea/0xc6d [<8104a942>] lock_acquire+0x92/0x101 [<8142f11d>] _raw_spin_lock_irqsave+0x2e/0x3e [<811c60be>] serial8250_console_write+0x8c/0x10c [<8104e402>] call_console_drivers.constprop.31+0x87/0x118 [<8104f5d5>] console_unlock+0x1d7/0x398 [<8104fb70>] vprintk_emit+0x3da/0x3e4 [<81425f76>] printk+0x17/0x19 [<8105bfa0>] clockevents_program_min_delta+0x104/0x116 [<8105c548>] clockevents_program_event+0xe7/0xf3 [<8105cc1c>] tick_program_event+0x1e/0x23 [<8103c43c>] hrtimer_force_reprogram+0x88/0x8f [<8103c49e>] __remove_hrtimer+0x5b/0x79 [<8103cb21>] hrtimer_try_to_cancel+0x49/0x66 [<8103cb4b>] hrtimer_cancel+0xd/0x18 [<8107f102>] perf_swevent_cancel_hrtimer.part.60+0x2b/0x30 [<81080705>] task_clock_event_stop+0x20/0x64 [<81080756>] task_clock_event_del+0xd/0xf [<81081350>] event_sched_out+0xab/0x11e [<810813e0>] group_sched_out+0x1d/0x66 [<81081682>] ctx_sched_out+0xaf/0xbf [<81081e04>] __perf_event_task_sched_out+0x1ed/0x34f [<8142cacc>] __schedule+0x4c6/0x4cb [<8142cae0>] schedule+0xf/0x11 [<8142f9a6>] work_resched+0x5/0x30 other info that might help us debug this: Chain exists of: &port_lock_key --> &ctx->lock --> hrtimer_bases.lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(hrtimer_bases.lock); lock(&ctx->lock); lock(hrtimer_bases.lock); lock(&port_lock_key); *** DEADLOCK *** 4 locks held by trinity-main/74: #0: (&rq->lock){-.-.-.}, at: [<8142c6f3>] __schedule+0xed/0x4cb #1: (&ctx->lock){......}, at: [<81081df3>] __perf_event_task_sched_out+0x1dc/0x34f #2: (hrtimer_bases.lock){-.-...}, at: [<8103caeb>] hrtimer_try_to_cancel+0x13/0x66 #3: (console_lock){+.+...}, at: [<8104fb5d>] vprintk_emit+0x3c7/0x3e4 stack backtrace: CPU: 0 PID: 74 Comm: trinity-main Not tainted 3.15.0-rc8-06195-g939f04b #2 00000000 81c3a310 8b995c14 81426f69 8b995c44 81425a99 8161f671 8161f570 8161f538 8161f559 8161f538 8b995c78 8b142bb0 00000004 8b142fdc 8b142bb0 8b995ca8 8104a62d 8b142fac 000016f2 81c3a310 00000001 00000001 00000003 Call Trace: [<81426f69>] dump_stack+0x16/0x18 [<81425a99>] print_circular_bug+0x18f/0x19c [<8104a62d>] __lock_acquire+0x9ea/0xc6d [<8104a942>] lock_acquire+0x92/0x101 [<811c60be>] ? serial8250_console_write+0x8c/0x10c [<811c6032>] ? wait_for_xmitr+0x76/0x76 [<8142f11d>] _raw_spin_lock_irqsave+0x2e/0x3e [<811c60be>] ? serial8250_console_write+0x8c/0x10c [<811c60be>] serial8250_console_write+0x8c/0x10c [<8104af87>] ? lock_release+0x191/0x223 [<811c6032>] ? wait_for_xmitr+0x76/0x76 [<8104e402>] call_console_drivers.constprop.31+0x87/0x118 [<8104f5d5>] console_unlock+0x1d7/0x398 [<8104fb70>] vprintk_emit+0x3da/0x3e4 [<81425f76>] printk+0x17/0x19 [<8105bfa0>] clockevents_program_min_delta+0x104/0x116 [<8105cc1c>] tick_program_event+0x1e/0x23 [<8103c43c>] hrtimer_force_reprogram+0x88/0x8f [<8103c49e>] __remove_hrtimer+0x5b/0x79 [<8103cb21>] hrtimer_try_to_cancel+0x49/0x66 [<8103cb4b>] hrtimer_cancel+0xd/0x18 [<8107f102>] perf_swevent_cancel_hrtimer.part.60+0x2b/0x30 [<81080705>] task_clock_event_stop+0x20/0x64 [<81080756>] task_clock_event_del+0xd/0xf [<81081350>] event_sched_out+0xab/0x11e [<810813e0>] group_sched_out+0x1d/0x66 [<81081682>] ctx_sched_out+0xaf/0xbf [<81081e04>] __perf_event_task_sched_out+0x1ed/0x34f [<8104416d>] ? __dequeue_entity+0x23/0x27 [<81044505>] ? pick_next_task_fair+0xb1/0x120 [<8142cacc>] __schedule+0x4c6/0x4cb [<81047574>] ? trace_hardirqs_off_caller+0xd7/0x108 [<810475b0>] ? trace_hardirqs_off+0xb/0xd [<81056346>] ? rcu_irq_exit+0x64/0x77 Fix the problem by using printk_deferred() which does not call into the scheduler. Reported-by: Fengguang Wu Signed-off-by: Jan Kara Signed-off-by: Thomas Gleixner Signed-off-by: Jiri Slaby

alarmtimer: Fix bug where relative alarm timers were treated as absolute

2014-07-29T15:01:45Z

commit 16927776ae757d0d132bdbfabbfe2c498342bd59 upstream. Sharvil noticed with the posix timer_settime interface, using the CLOCK_REALTIME_ALARM or CLOCK_BOOTTIME_ALARM clockid, if the users tried to specify a relative time timer, it would incorrectly be treated as absolute regardless of the state of the flags argument. This patch corrects this, properly checking the absolute/relative flag, as well as adds further error checking that no invalid flag bits are set. Reported-by: Sharvil Nanavati Signed-off-by: John Stultz Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Prarit Bhargava Cc: Sharvil Nanavati Link: http://lkml.kernel.org/r/1404767171-6902-1-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner Signed-off-by: Jiri Slaby

tick-sched: Check tick_nohz_enabled in tick_nohz_switch_to_nohz()

2014-06-27T08:25:12Z

commit 27630532ef5ead28b98cfe28d8f95222ef91c2b7 upstream. Since commit d689fe222 (NOHZ: Check for nohz active instead of nohz enabled) the tick_nohz_switch_to_nohz() function returns because it checks for the tick_nohz_active flag. This can't be set, because the function itself sets it. Undo the change in tick_nohz_switch_to_nohz(). Signed-off-by: Viresh Kumar Cc: linaro-kernel@lists.linaro.org Cc: fweisbec@gmail.com Cc: Arvind.Chauhan@arm.com Cc: linaro-networking@linaro.org Cc: # 3.13+ Link: http://lkml.kernel.org/r/40939c05f2d65d781b92b20302b02243d0654224.1397537987.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner Signed-off-by: Jiri Slaby

tick-common: Fix wrong check in tick_check_replacement()

2014-05-29T09:38:11Z

commit 521c42990e9d561ed5ed9f501f07639d0512b3c9 upstream. tick_check_replacement() returns if a replacement of clock_event_device is possible or not. It does this as the first check: if (tick_check_percpu(curdev, newdev, smp_processor_id())) return false; Thats wrong. tick_check_percpu() returns true when the device is useable. Check for false instead. [ tglx: Massaged changelog ] Signed-off-by: Viresh Kumar Cc: linaro-kernel@lists.linaro.org Cc: fweisbec@gmail.com Cc: Arvind.Chauhan@arm.com Cc: linaro-networking@linaro.org Link: http://lkml.kernel.org/r/486a02efe0246635aaba786e24b42d316438bf3b.1397537987.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner Signed-off-by: Jiri Slaby

NOHZ: Check for nohz active instead of nohz enabled

2014-03-12T12:25:35Z

commit d689fe222a858c767cb8594faf280048e532b53f upstream. RCU and the fine grained idle time accounting functions check tick_nohz_enabled. But that variable is merily telling that NOHZ has been enabled in the config and not been disabled on the command line. But it does not tell anything about nohz being active. That's what all this should check for. Matthew reported, that the idle accounting on his old P1 machine showed bogus values, when he enabled NOHZ in the config and did not disable it on the kernel command line. The reason is that his machine uses (refined) jiffies as a clocksource which explains why the "fine" grained accounting went into lala land, because it depends on when the system goes and leaves idle relative to the jiffies increment. Provide a tick_nohz_active indicator and let RCU and the accounting code use this instead of tick_nohz_enable. Reported-and-tested-by: Matthew Whitehead Signed-off-by: Thomas Gleixner Reviewed-by: Steven Rostedt Reviewed-by: Paul E. McKenney Cc: john.stultz@linaro.org Cc: mwhitehe@redhat.com Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311132052240.30673@ionos.tec.linutronix.de Signed-off-by: Jiri Slaby

nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off

2014-03-12T12:25:35Z

commit 0e576acbc1d9600cf2d9b4a141a2554639959d50 upstream. If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ. If CONFIG_NO_HZ=y and the nohz functionality is disabled via the command line option "nohz=off" or not enabled due to missing hardware support, then tick_nohz_get_sleep_length() returns 0. That happens because ts->sleep_length is never set in that case. Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive. Reported-by: Michal Hocko Reported-by: Borislav Petkov Signed-off-by: Thomas Gleixner Signed-off-by: Jiri Slaby

time: Fix overflow when HZ is smaller than 60

2014-02-22T21:32:29Z

commit 80d767d770fd9c697e434fd080c2db7b5c60c6dd upstream. When compiling for the IA-64 ski emulator, HZ is set to 32 because the emulation is slow and we don't want to waste too many cycles processing timers. Alpha also has an option to set HZ to 32. This causes integer underflow in kernel/time/jiffies.c: kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow] .mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */ ^ This patch reduces the JIFFIES_SHIFT value to avoid the overflow. Signed-off-by: Mikulas Patocka Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

tick: Clear broadcast pending bit when switching to oneshot

2014-02-22T21:32:29Z

commit dd5fd9b91a77b4c9c28b7ef9c181b1a875820d0a upstream. AMD systems which use the C1E workaround in the amd_e400_idle routine trigger the WARN_ON_ONCE in the broadcast code when onlining a CPU. The reason is that the idle routine of those AMD systems switches the cpu into forced broadcast mode early on before the newly brought up CPU can switch over to high resolution / NOHZ mode. The timer related CPU1 bringup looks like this: clockevent_register_device(local_apic); tick_setup(local_apic); ... idle() tick_broadcast_on_off(FORCE); tick_broadcast_oneshot_control(ENTER) cpumask_set(cpu, broadcast_oneshot_mask); halt(); Now the broadcast interrupt on CPU0 sets CPU1 in the broadcast_pending_mask and wakes CPU1. So CPU1 continues: local_apic_timer_interrupt() tick_handle_periodic(); softirq() tick_init_highres(); cpumask_clr(cpu, broadcast_oneshot_mask); tick_broadcast_oneshot_control(ENTER) WARN_ON(cpumask_test(cpu, broadcast_pending_mask); So while we remove CPU1 from the broadcast_oneshot_mask when we switch over to highres mode, we do not clear the pending bit, which then triggers the warning when we go back to idle. The reason why this is only visible on C1E affected AMD systems is that the other machines enter the deep sleep states via acpi_idle/intel_idle and exit the broadcast mode before executing the remote triggered local_apic_timer_interrupt. So the pending bit is already cleared when the switch over to highres mode is clearing the oneshot mask. The solution is simple: Clear the pending bit together with the mask bit when we switch over to highres mode. Stanislaw came up independently with the same patch by enforcing the C1E workaround and debugging the fallout. I picked mine, because mine has a changelog :) Reported-by: poma Debugged-by: Stanislaw Gruszka Signed-off-by: Thomas Gleixner Cc: Olaf Hering Cc: Dave Jones Cc: Justin M. Forbes Cc: Josh Boyer Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1402111434180.21991@ionos.tec.linutronix.de Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

timekeeping: Fix missing timekeeping_update in suspend path

2014-02-13T21:50:26Z

commit 330a1617b0a6268d427aa5922c94d082b1d3e96d upstream. Since 48cdc135d4840 (Implement a shadow timekeeper), we have to call timekeeping_update() after any adjustment to the timekeeping structure in order to make sure that any adjustments to the structure persist. In the timekeeping suspend path, we udpate the timekeeper structure, so we should be sure to update the shadow-timekeeper before releasing the timekeeping locks. Currently this isn't done. In most cases, the next time related code to run would be timekeeping_resume, which does update the shadow-timekeeper, but in an abundence of caution, this patch adds the call to timekeeping_update() in the suspend path. Cc: Sasha Levin Cc: Thomas Gleixner Cc: Prarit Bhargava Cc: Richard Cochran Cc: Ingo Molnar Signed-off-by: John Stultz Signed-off-by: Greg Kroah-Hartman

timekeeping: Fix CLOCK_TAI timer/nanosleep delays

2014-02-13T21:50:26Z

commit 04005f6011e3b504cd4d791d9769f7cb9a3b2eae upstream. A think-o in the calculation of the monotonic -> tai time offset results in CLOCK_TAI timers and nanosleeps to expire late (the latency is ~2x the tai offset). Fix this by adding the tai offset from the realtime offset instead of subtracting. Cc: Sasha Levin Cc: Thomas Gleixner Cc: Prarit Bhargava Cc: Richard Cochran Cc: Ingo Molnar Signed-off-by: John Stultz Signed-off-by: Greg Kroah-Hartman