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Sometimes boot loaders set CPU frequency to a value outside of frequency table
present with cpufreq core. In such cases CPU might be unstable if it has to run
on that frequency for long duration of time and so its better to set it to a
frequency which is specified in frequency table.
Sachin recently found this problem with cpufreq-cpu0 driver when he was testing
it for Exynos.
Set this flag for cpufreq-cpu0 driver.
Reported-and-tested-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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'copy_prev_load' was recently added by commit: 18b46ab (cpufreq: governor: Be
friendly towards latency-sensitive bursty workloads).
It actually is a bit redundant as we also have 'prev_load' which can store any
integer value and can be used instead of 'copy_prev_load' by setting it zero.
True load can also turn out to be zero during long idle intervals (and hence the
actual value of 'prev_load' and the overloaded value can clash). However this is
not a problem because, if the true load was really zero in the previous
interval, it makes sense to evaluate the load afresh for the current interval
rather than copying the previous load.
So, drop 'copy_prev_load' and use 'prev_load' instead.
Update comments as well to make it more clear.
There is another change here which was probably missed by Srivatsa during the
last version of updates he made. The unlikely in the 'if' statement was covering
only half of the condition and the whole line should actually come under it.
Also checkpatch is made more silent as it was reporting this (--strict option):
CHECK: Alignment should match open parenthesis
+ if (unlikely(wall_time > (2 * sampling_rate) &&
+ j_cdbs->prev_load)) {
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Cpufreq governors like the ondemand governor calculate the load on the CPU
periodically by employing deferrable timers. A deferrable timer won't fire
if the CPU is completely idle (and there are no other timers to be run), in
order to avoid unnecessary wakeups and thus save CPU power.
However, the load calculation logic is agnostic to all this, and this can
lead to the problem described below.
Time (ms) CPU 1
100 Task-A running
110 Governor's timer fires, finds load as 100% in the last
10ms interval and increases the CPU frequency.
110.5 Task-A running
120 Governor's timer fires, finds load as 100% in the last
10ms interval and increases the CPU frequency.
125 Task-A went to sleep. With nothing else to do, CPU 1
went completely idle.
200 Task-A woke up and started running again.
200.5 Governor's deferred timer (which was originally programmed
to fire at time 130) fires now. It calculates load for the
time period 120 to 200.5, and finds the load is almost zero.
Hence it decreases the CPU frequency to the minimum.
210 Governor's timer fires, finds load as 100% in the last
10ms interval and increases the CPU frequency.
So, after the workload woke up and started running, the frequency was suddenly
dropped to absolute minimum, and after that, there was an unnecessary delay of
10ms (sampling period) to increase the CPU frequency back to a reasonable value.
And this pattern repeats for every wake-up-from-cpu-idle for that workload.
This can be quite undesirable for latency- or response-time sensitive bursty
workloads. So we need to fix the governor's logic to detect such wake-up-from-
cpu-idle scenarios and start the workload at a reasonably high CPU frequency.
One extreme solution would be to fake a load of 100% in such scenarios. But
that might lead to undesirable side-effects such as frequency spikes (which
might also need voltage changes) especially if the previous frequency happened
to be very low.
We just want to avoid the stupidity of dropping down the frequency to a minimum
and then enduring a needless (and long) delay before ramping it up back again.
So, let us simply carry forward the previous load - that is, let us just pretend
that the 'load' for the current time-window is the same as the load for the
previous window. That way, the frequency and voltage will continue to be set
to whatever values they were set at previously. This means that bursty workloads
will get a chance to influence the CPU frequency at which they wake up from
cpu-idle, based on their past execution history. Thus, they might be able to
avoid suffering from slow wakeups and long response-times.
However, we should take care not to over-do this. For example, such a "copy
previous load" logic will benefit cases like this: (where # represents busy
and . represents idle)
##########.........#########.........###########...........##########........
but it will be detrimental in cases like the one shown below, because it will
retain the high frequency (copied from the previous interval) even in a mostly
idle system:
##########.........#.................#.....................#...............
(i.e., the workload finished and the remaining tasks are such that their busy
periods are smaller than the sampling interval, which causes the timer to
always get deferred. So, this will make the copy-previous-load logic copy
the initial high load to subsequent idle periods over and over again, thus
keeping the frequency high unnecessarily).
So, we modify this copy-previous-load logic such that it is used only once
upon every wakeup-from-idle. Thus if we have 2 consecutive idle periods, the
previous load won't get blindly copied over; cpufreq will freshly evaluate the
load in the second idle interval, thus ensuring that the system comes back to
its normal state.
[ The right way to solve this whole problem is to teach the CPU frequency
governors to also track load on a per-task basis, not just a per-CPU basis,
and then use both the data sources intelligently to set the appropriate
frequency on the CPUs. But that involves redesigning the cpufreq subsystem,
so this patch should make the situation bearable until then. ]
Experimental results:
+-------------------+
I ran a modified version of ebizzy (called 'sleeping-ebizzy') that sleeps in
between its execution such that its total utilization can be a user-defined
value, say 10% or 20% (higher the utilization specified, lesser the amount of
sleeps injected). This ebizzy was run with a single-thread, tied to CPU 8.
Behavior observed with tracing (sample taken from 40% utilization runs):
------------------------------------------------------------------------
Without patch:
~~~~~~~~~~~~~~
kworker/8:2-12137 416.335742: cpu_frequency: state=2061000 cpu_id=8
kworker/8:2-12137 416.335744: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
<...>-40753 416.345741: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
kworker/8:2-12137 416.345744: cpu_frequency: state=4123000 cpu_id=8
kworker/8:2-12137 416.345746: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
<...>-40753 416.355738: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
<snip> --------------------------------------------------------------------- <snip>
<...>-40753 416.402202: sched_switch: prev_comm=ebizzy ==> next_comm=swapper/8
<idle>-0 416.502130: sched_switch: prev_comm=swapper/8 ==> next_comm=ebizzy
<...>-40753 416.505738: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
kworker/8:2-12137 416.505739: cpu_frequency: state=2061000 cpu_id=8
kworker/8:2-12137 416.505741: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
<...>-40753 416.515739: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
kworker/8:2-12137 416.515742: cpu_frequency: state=4123000 cpu_id=8
kworker/8:2-12137 416.515744: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
Observation: Ebizzy went idle at 416.402202, and started running again at
416.502130. But cpufreq noticed the long idle period, and dropped the frequency
at 416.505739, only to increase it back again at 416.515742, realizing that the
workload is in-fact CPU bound. Thus ebizzy needlessly ran at the lowest frequency
for almost 13 milliseconds (almost 1 full sample period), and this pattern
repeats on every sleep-wakeup. This could hurt latency-sensitive workloads quite
a lot.
With patch:
~~~~~~~~~~~
kworker/8:2-29802 464.832535: cpu_frequency: state=2061000 cpu_id=8
<snip> --------------------------------------------------------------------- <snip>
kworker/8:2-29802 464.962538: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
<...>-40738 464.972533: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
kworker/8:2-29802 464.972536: cpu_frequency: state=4123000 cpu_id=8
kworker/8:2-29802 464.972538: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
<...>-40738 464.982531: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
<snip> --------------------------------------------------------------------- <snip>
kworker/8:2-29802 465.022533: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
<...>-40738 465.032531: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
kworker/8:2-29802 465.032532: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
<...>-40738 465.035797: sched_switch: prev_comm=ebizzy ==> next_comm=swapper/8
<idle>-0 465.240178: sched_switch: prev_comm=swapper/8 ==> next_comm=ebizzy
<...>-40738 465.242533: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
kworker/8:2-29802 465.242535: sched_switch: prev_comm=kworker/8:2 ==> next_comm=ebizzy
<...>-40738 465.252531: sched_switch: prev_comm=ebizzy ==> next_comm=kworker/8:2
Observation: Ebizzy went idle at 465.035797, and started running again at
465.240178. Since ebizzy was the only real workload running on this CPU,
cpufreq retained the frequency at 4.1Ghz throughout the run of ebizzy, no
matter how many times ebizzy slept and woke-up in-between. Thus, ebizzy
got the 10ms worth of 4.1 Ghz benefit during every sleep-wakeup (as compared
to the run without the patch) and this boost gave a modest improvement in total
throughput, as shown below.
Sleeping-ebizzy records-per-second:
-----------------------------------
Utilization Without patch With patch Difference (Absolute and % values)
10% 274767 277046 + 2279 (+0.829%)
20% 543429 553484 + 10055 (+1.850%)
40% 1090744 1107959 + 17215 (+1.578%)
60% 1634908 1662018 + 27110 (+1.658%)
A rudimentary and somewhat approximately latency-sensitive workload such as
sleeping-ebizzy itself showed a consistent, noticeable performance improvement
with this patch. Hence, workloads that are truly latency-sensitive will benefit
quite a bit from this change. Moreover, this is an overall win-win since this
patch does not hurt power-savings at all (because, this patch does not reduce
the idle time or idle residency; and the high frequency of the CPU when it goes
to cpu-idle does not affect/hurt the power-savings of deep idle states).
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Commit 6712d2931933 (cpufreq: ppc-corenet-cpufreq: Fix __udivdi3 modpost
error) used the remainder from do_div instead of the quotient. Fix that
and add one to ensure minimum is met.
Fixes: 6712d2931933 (cpufreq: ppc-corenet-cpufreq: Fix __udivdi3 modpost error)
Signed-off-by: Ed Swarthout <Ed.Swarthout@freescale.com>
Cc: 3.15+ <stable@vger.kernel.org> # 3.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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This reverts commit 4920ab84979d (cpufreq: Enable big.LITTLE cpufreq
driver on arm64) that breaks build on arm64.
Fixes: 4920ab84979d (cpufreq: Enable big.LITTLE cpufreq driver on arm64)
Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Tegra has been switching to intermediate frequency (pll_p_clk) forever.
CPUFreq core has better support for handling notifications for these
frequencies and so we can adapt Tegra's driver to it.
Also do a WARN() if clk_set_parent() fails while moving back to pll_x
as we should have atleast restored to earlier frequency on error.
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Douglas Anderson, recently pointed out an interesting problem due to which
udelay() was expiring earlier than it should.
While transitioning between frequencies few platforms may temporarily switch to
a stable frequency, waiting for the main PLL to stabilize.
For example: When we transition between very low frequencies on exynos, like
between 200MHz and 300MHz, we may temporarily switch to a PLL running at 800MHz.
No CPUFREQ notification is sent for that. That means there's a period of time
when we're running at 800MHz but loops_per_jiffy is calibrated at between 200MHz
and 300MHz. And so udelay behaves badly.
To get this fixed in a generic way, introduce another set of callbacks
get_intermediate() and target_intermediate(), only for drivers with
target_index() and CPUFREQ_ASYNC_NOTIFICATION unset.
get_intermediate() should return a stable intermediate frequency platform wants
to switch to, and target_intermediate() should set CPU to that frequency,
before jumping to the frequency corresponding to 'index'. Core will take care of
sending notifications and driver doesn't have to handle them in
target_intermediate() or target_index().
NOTE: ->target_index() should restore to policy->restore_freq in case of
failures as core would send notifications for that.
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Conflicts:
arch/mips/loongson/lemote-2f/clock.c
drivers/cpufreq/intel_pstate.c
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This change makes the busy calculation using 64 bit math which prevents
overflow for large values of aperf/mperf.
Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Signed-off-by: Doug Smythies <dsmythies@telus.net>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The PID assumes that samples are of equal time, which for a deferable
timers this is not true when the system goes idle. This causes the
PID to take a long time to converge to the min P state and depending
on the pattern of the idle load can make the P state appear stuck.
The hold-off value of three sample times before using the scaling is
to give a grace period for applications that have high performance
requirements and spend a lot of time idle, The poster child for this
behavior is the ffmpeg benchmark in the Phoronix test suite.
Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Changing to fixed point math throughout the busy calculation in
commit e66c1768 (Change busy calculation to use fixed point
math.) Introduced some inaccuracies by rounding the busy value at two
points in the calculation. This change removes roundings and moves
the rounding to the output of the PID where the calculations are
complete and the value returned as an integer.
Fixes: e66c17683746 (intel_pstate: Change busy calculation to use fixed point math.)
Reported-by: Doug Smythies <dsmythies@telus.net>
Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Commit fcb6a15c (intel_pstate: Take core C0 time into account for core
busy calculation) introduced a regression referenced below. The issue
with "lockup" after suspend that this commit was addressing is now dealt
with in the suspend path.
Fixes: fcb6a15c2e7e (intel_pstate: Take core C0 time into account for core busy calculation)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=66581
Link: https://bugzilla.kernel.org/show_bug.cgi?id=75121
Reported-by: Doug Smythies <dsmythies@telus.net>
Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc
Pull powerpc fix from Ben Herrenschmidt:
"Here's just one trivial patch to wire up sys_renameat2 which I seem to
have completely missed so far.
(My test build scripts fwd me warnings but miss the ones generated for
missing syscalls)"
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
powerpc: Wire renameat2() syscall
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Pull MIPS fixes from Ralf Baechle:
"A fair number of fixes across the field. Nothing terribly
complicated; the one liners in below changelog should be fairly
descriptive.
Noteworthy is the SB1 change which the result of changes to binutils
resulting in one big gas warning for most files being assembled as
well as the asid_cache and branch emulation fixes which fix corruption
or possible uninteded behaviour of kernel or application code. The
remainder of fixes are more platforms or subsystem specific"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
MIPS: R46000: Fix Micro-assembler field overflow for R4600 V2
MIPS: ptrace: Avoid smp_processor_id() in preemptible code
MIPS: Lemote 2F: cs5536: mfgpt: use raw locks
MIPS: SB1: Fix excessive kernel warnings.
MIPS: RC32434: fix broken PCI resource initialization
MIPS: malta: memory.c: Initialize the 'memsize' variable
MIPS: Fix typo when reporting cache and ftlb errors for ImgTec cores
MIPS: Fix inconsistancy of __NR_Linux_syscalls value
MIPS: Fix branch emulation of branch likely instructions.
MIPS: Fix a typo error in AUDIT_ARCH definition
MIPS: Change type of asid_cache to unsigned long
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
"Various fixlets, mostly related to the (root-only) SCHED_DEADLINE
policy, but also a hotplug bug fix and a fix for a NR_CPUS related
overallocation bug causing a suspend/resume regression"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Fix hotplug vs. set_cpus_allowed_ptr()
sched/cpupri: Replace NR_CPUS arrays
sched/deadline: Replace NR_CPUS arrays
sched/deadline: Restrict user params max value to 2^63 ns
sched/deadline: Change sched_getparam() behaviour vs SCHED_DEADLINE
sched: Disallow sched_attr::sched_policy < 0
sched: Make sched_setattr() correctly return -EFBIG
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Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core futex/rtmutex fixes from Thomas Gleixner:
"Three fixlets for long standing issues in the futex/rtmutex code
unearthed by Dave Jones syscall fuzzer:
- Add missing early deadlock detection checks in the futex code
- Prevent user space from attaching a futex to kernel threads
- Make the deadlock detector of rtmutex work again
Looks large, but is more comments than code change"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rtmutex: Fix deadlock detector for real
futex: Prevent attaching to kernel threads
futex: Add another early deadlock detection check
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Pull drm fixes from Dave Airlie:
"Mostly quiet now:
i915:
fixing userspace visiblie issues, all stable marked
radeon:
one more pll fix, two crashers, one suspend/resume regression"
* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
drm/radeon: Resume fbcon last
drm/radeon: only allocate necessary size for vm bo list
drm/radeon: don't allow RADEON_GEM_DOMAIN_CPU for command submission
drm/radeon: avoid crash if VM command submission isn't available
drm/radeon: lower the ref * post PLL maximum once more
drm/i915: Prevent negative relocation deltas from wrapping
drm/i915: Only copy back the modified fields to userspace from execbuffer
drm/i915: Fix dynamic allocation of physical handles
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lock_parent() very much on purpose does nested locking of dentries, and
is careful to maintain the right order (lock parent first). But because
it didn't annotate the nested locking order, lockdep thought it might be
a deadlock on d_lock, and complained.
Add the proper annotation for the inner locking of the child dentry to
make lockdep happy.
Introduced by commit 046b961b45f9 ("shrink_dentry_list(): take parent's
->d_lock earlier").
Reported-and-tested-by: Josh Boyer <jwboyer@fedoraproject.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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So a few people complained that
commit 177cf92de4aa97ec1435987e91696ed8b5023130
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Tue Apr 1 22:14:59 2014 +0200
drm/crtc-helpers: fix dpms on logic
which was merged into 3.15-rc1, broke resume on radeons. Strangely git
bisect lead everyone to
commit 25f397a429dfa43f22c278d0119a60a343aa568f
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Fri Jul 19 18:57:11 2013 +0200
drm/crtc-helper: explicit DPMS on after modeset
which was merged long ago and actually part of 3.14.
Digging deeper I've noticed (again) that the call to
drm_helper_resume_force_mode in the radeon resume handlers was a no-op
previously because everything gets shut down on suspend. radeon does
this with explicit calls to drm_helper_connector_dpms with DPMS_OFF.
But with 177c we now force the dpms state to ON, so suddenly
resume_force_mode actually forced the crtcs back on.
This is the intention of the change after all, the problem is that
radeon resumes the fbdev console layer _before_ restoring the display,
through calling fb_set_suspend. And fbcon does an immediate ->set_par,
which in turn causes the same forced mode restore to happen.
Two concurrent modeset operations didn't lead to happiness. Fix this
by delaying the fbcon resume until the end of the readeon resum
functions.
v2: Fix up a bit of the spelling fail.
References: https://lkml.org/lkml/2014/5/29/1043
References: https://lkml.org/lkml/2014/5/2/388
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=74751
Tested-by: Ken Moffat <zarniwhoop@ntlworld.com>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Ken Moffat <zarniwhoop@ntlworld.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@gmail.com>
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git://people.freedesktop.org/~deathsimple/linux into drm-fixes
this is the next pull request for stashed up radeon fixes for 3.15. This is finally calming down with only four patches in this pull request.
* 'drm-fixes-3.15' of git://people.freedesktop.org/~deathsimple/linux:
drm/radeon: only allocate necessary size for vm bo list
drm/radeon: don't allow RADEON_GEM_DOMAIN_CPU for command submission
drm/radeon: avoid crash if VM command submission isn't available
drm/radeon: lower the ref * post PLL maximum once more
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git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
Pull input subsystem fixes from Dmitry Torokhov:
"A couple of driver/build fixups and also redone quirk for Synaptics
touchpads on Lenovo boxes (now using PNP IDs instead of DMI data to
limit number of quirks)"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: synaptics - change min/max quirk table to pnp-id matching
Input: synaptics - add a matches_pnp_id helper function
Input: synaptics - T540p - unify with other LEN0034 models
Input: synaptics - add min/max quirk for the ThinkPad W540
Input: ambakmi - request a shared interrupt for AMBA KMI devices
Input: pxa27x-keypad - fix generating scancode
Input: atmel-wm97xx - only build for AVR32
Input: fix ps2/serio module dependency
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git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394
Pull firewire fix from Stefan Richter:
"A regression fix for the IEEE 1394 subsystem: re-enable IRQ-based
asynchronous request reception at addresses below 128 TB"
* tag 'firewire-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
firewire: revert to 4 GB RDMA, fix protocols using Memory Space
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git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device-mapper fixes from Mike Snitzer:
"A dm-cache stable fix to split discards on cache block boundaries
because dm-cache cannot yet handle discards that span cache blocks.
Really fix a dm-mpath LOCKDEP warning that was introduced in -rc1.
Add a 'no_space_timeout' control to dm-thinp to restore the ability to
queue IO indefinitely when no data space is available. This fixes a
change in behavior that was introduced in -rc6 where the timeout
couldn't be disabled"
* tag 'dm-3.15-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm mpath: really fix lockdep warning
dm cache: always split discards on cache block boundaries
dm thin: add 'no_space_timeout' dm-thin-pool module param
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While I play inhouse patches with much memory pressure on qemu-kvm,
3.14 kernel was randomly crashed. The reason was kernel stack overflow.
When I investigated the problem, the callstack was a little bit deeper
by involve with reclaim functions but not direct reclaim path.
I tried to diet stack size of some functions related with alloc/reclaim
so did a hundred of byte but overflow was't disappeard so that I encounter
overflow by another deeper callstack on reclaim/allocator path.
Of course, we might sweep every sites we have found for reducing
stack usage but I'm not sure how long it saves the world(surely,
lots of developer start to add nice features which will use stack
agains) and if we consider another more complex feature in I/O layer
and/or reclaim path, it might be better to increase stack size(
meanwhile, stack usage on 64bit machine was doubled compared to 32bit
while it have sticked to 8K. Hmm, it's not a fair to me and arm64
already expaned to 16K. )
So, my stupid idea is just let's expand stack size and keep an eye
toward stack consumption on each kernel functions via stacktrace of ftrace.
For example, we can have a bar like that each funcion shouldn't exceed 200K
and emit the warning when some function consumes more in runtime.
Of course, it could make false positive but at least, it could make a
chance to think over it.
I guess this topic was discussed several time so there might be
strong reason not to increase kernel stack size on x86_64, for me not
knowing so Ccing x86_64 maintainers, other MM guys and virtio
maintainers.
Here's an example call trace using up the kernel stack:
Depth Size Location (51 entries)
----- ---- --------
0) 7696 16 lookup_address
1) 7680 16 _lookup_address_cpa.isra.3
2) 7664 24 __change_page_attr_set_clr
3) 7640 392 kernel_map_pages
4) 7248 256 get_page_from_freelist
5) 6992 352 __alloc_pages_nodemask
6) 6640 8 alloc_pages_current
7) 6632 168 new_slab
8) 6464 8 __slab_alloc
9) 6456 80 __kmalloc
10) 6376 376 vring_add_indirect
11) 6000 144 virtqueue_add_sgs
12) 5856 288 __virtblk_add_req
13) 5568 96 virtio_queue_rq
14) 5472 128 __blk_mq_run_hw_queue
15) 5344 16 blk_mq_run_hw_queue
16) 5328 96 blk_mq_insert_requests
17) 5232 112 blk_mq_flush_plug_list
18) 5120 112 blk_flush_plug_list
19) 5008 64 io_schedule_timeout
20) 4944 128 mempool_alloc
21) 4816 96 bio_alloc_bioset
22) 4720 48 get_swap_bio
23) 4672 160 __swap_writepage
24) 4512 32 swap_writepage
25) 4480 320 shrink_page_list
26) 4160 208 shrink_inactive_list
27) 3952 304 shrink_lruvec
28) 3648 80 shrink_zone
29) 3568 128 do_try_to_free_pages
30) 3440 208 try_to_free_pages
31) 3232 352 __alloc_pages_nodemask
32) 2880 8 alloc_pages_current
33) 2872 200 __page_cache_alloc
34) 2672 80 find_or_create_page
35) 2592 80 ext4_mb_load_buddy
36) 2512 176 ext4_mb_regular_allocator
37) 2336 128 ext4_mb_new_blocks
38) 2208 256 ext4_ext_map_blocks
39) 1952 160 ext4_map_blocks
40) 1792 384 ext4_writepages
41) 1408 16 do_writepages
42) 1392 96 __writeback_single_inode
43) 1296 176 writeback_sb_inodes
44) 1120 80 __writeback_inodes_wb
45) 1040 160 wb_writeback
46) 880 208 bdi_writeback_workfn
47) 672 144 process_one_work
48) 528 112 worker_thread
49) 416 240 kthread
50) 176 176 ret_from_fork
[ Note: the problem is exacerbated by certain gcc versions that seem to
generate much bigger stack frames due to apparently bad coalescing of
temporaries and generating too many spills. Rusty saw gcc-4.6.4 using
35% more stack on the virtio path than 4.8.2 does, for example.
Minchan not only uses such a bad gcc version (4.6.3 in his case), but
some of the stack use is due to debugging (CONFIG_DEBUG_PAGEALLOC is
what causes that kernel_map_pages() frame, for example). But we're
clearly getting too close.
The VM code also seems to have excessive stack frames partly for the
same compiler reason, triggered by excessive inlining and lots of
function arguments.
We need to improve on our stack use, but in the meantime let's do this
simple stack increase too. Unlike most earlier reports, there is
nothing simple that stands out as being really horribly wrong here,
apart from the fact that the stack frames are just bigger than they
should need to be. - Linus ]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michael S Tsirkin <mst@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: PJ Waskiewicz <pjwaskiewicz@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs dcache livelock fix from Al Viro:
"Fixes for livelocks in shrink_dentry_list() introduced by fixes to
shrink list corruption; the root cause was that trylock of parent's
->d_lock could be disrupted by d_walk() happening on other CPUs,
resulting in shrink_dentry_list() making no progress *and* the same
d_walk() being called again and again for as long as
shrink_dentry_list() doesn't get past that mess.
The solution is to have shrink_dentry_list() treat that trylock
failure not as 'try to do the same thing again', but 'lock them in the
right order'"
* 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
dentry_kill() doesn't need the second argument now
dealing with the rest of shrink_dentry_list() livelock
shrink_dentry_list(): take parent's ->d_lock earlier
expand dentry_kill(dentry, 0) in shrink_dentry_list()
split dentry_kill()
lift the "already marked killed" case into shrink_dentry_list()
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it's 1 in the only remaining caller.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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We have the same problem with ->d_lock order in the inner loop, where
we are dropping references to ancestors. Same solution, basically -
instead of using dentry_kill() we use lock_parent() (introduced in the
previous commit) to get that lock in a safe way, recheck ->d_count
(in case if lock_parent() has ended up dropping and retaking ->d_lock
and somebody managed to grab a reference during that window), trylock
the inode->i_lock and use __dentry_kill() to do the rest.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The cause of livelocks there is that we are taking ->d_lock on
dentry and its parent in the wrong order, forcing us to use
trylock on the parent's one. d_walk() takes them in the right
order, and unfortunately it's not hard to create a situation
when shrink_dentry_list() can't make progress since trylock
keeps failing, and shrink_dcache_parent() or check_submounts_and_drop()
keeps calling d_walk() disrupting the very shrink_dentry_list() it's
waiting for.
Solution is straightforward - if that trylock fails, let's unlock
the dentry itself and take locks in the right order. We need to
stabilize ->d_parent without holding ->d_lock, but that's doable
using RCU. And we'd better do that in the very beginning of the
loop in shrink_dentry_list(), since the checks on refcount, etc.
would need to be redone anyway.
That deals with a half of the problem - killing dentries on the
shrink list itself. Another one (dropping their parents) is
in the next commit.
locking parent is interesting - it would be easy to do rcu_read_lock(),
lock whatever we think is a parent, lock dentry itself and check
if the parent is still the right one. Except that we need to check
that *before* locking the dentry, or we are risking taking ->d_lock
out of order. Fortunately, once the D1 is locked, we can check if
D2->d_parent is equal to D1 without the need to lock D2; D2->d_parent
can start or stop pointing to D1 only under D1->d_lock, so taking
D1->d_lock is enough. In other words, the right solution is
rcu_read_lock/lock what looks like parent right now/check if it's
still our parent/rcu_read_unlock/lock the child.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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No need to always allocate the theoretical maximum here.
Signed-off-by: Christian König <christian.koenig@amd.com>
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It hangs the hardware.
Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org
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Signed-off-by: Christian König <christian.koenig@amd.com>
CC: stable@vger.kernel.org
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Let's be conservative and use 100 here until we find something better.
Bugs: https://bugzilla.kernel.org/show_bug.cgi?id=75241
Signed-off-by: Christian König <christian.koenig@amd.com>
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Pull ARM fixes from Russell King:
"The usual random collection of relatively small ARM fixes"
* 'fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
ARM: 8063/1: bL_switcher: fix individual online status reporting of removed CPUs
ARM: 8064/1: fix v7-M signal return
ARM: 8057/1: amba: Add Qualcomm vendor ID.
ARM: 8052/1: unwind: Fix handling of "Pop r4-r[4+nnn],r14" opcode
ARM: 8051/1: put_user: fix possible data corruption in put_user
ARM: 8048/1: fix v7-M setup stack location
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fix from Will Deacon:
"Fix CoW regression for transparent hugepages by routing set_pmd_at to
set_pte_at, which correctly handles PTE_WRITE and will mark the
resulting table entry as read-only where appropriate"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: mm: fix pmd_write CoW brokenness
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull ACPI and power management fixes from Rafael Wysocki:
"These are three stable-candidate fixes, one for the ACPI thermal
driver and two for cpufreq drivers.
Specifics:
- A workqueue is destroyed too early during the ACPI thermal driver
module unload which leads to a NULL pointer dereference in the
driver's remove callback. Fix from Aaron Lu.
- A wrong argument is passed to devm_regulator_get_optional() in the
probe routine of the cpu0 cpufreq driver which leads to resource
leaks if the driver is unbound from the cpufreq platform device.
Fix from Lucas Stach.
- A lock is missing in cpufreq_governor_dbs() which leads to memory
corruption and NULL pointer dereferences during system
suspend/resume, for example. Fix from Bibek Basu"
* tag 'pm+acpi-3.15-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI / thermal: fix workqueue destroy order
cpufreq: cpu0: drop wrong devm usage
cpufreq: remove race while accessing cur_policy
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git://git.linaro.org/people/mike.turquette/linux
Pull clock fixes from Mike Turquette:
"Small number of user-visible regression fixes for clock drivers.
There is a memory leak fix for an ST platform, an infinite Loop Of
Doom fix for the recent changes to the basic clock divider (hopefully
the last fix for those recent changes) and some Tegra PLL changes
which keep PCI from being hosed on that platform"
* tag 'clk-fixes-for-linus' of git://git.linaro.org/people/mike.turquette/linux:
clk: st: Fix memory leak
clk: divider: Fix table round up function
clk: tegra: Fix enabling of PLLE
clk: tegra: Introduce divider mask and shift helpers
clk: tegra: Fix PLLE programming
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Undo a feature introduced in v3.14 by commit fcd46b34425d
"firewire: Enable remote DMA above 4 GB". That change raised the
minimum address at which protocol drivers and user programs can register
for request reception from 0x0001'0000'0000 to 0x8000'0000'0000.
It turned out that at least one vendor-specific protocol exists which
uses lower addresses: https://bugzilla.kernel.org/show_bug.cgi?id=76921
For the time being, revert most of commit fcd46b34425d so that affected
protocols work like with kernel v3.13 and before. Just keep the valid
documentation parts from the regressing commit, and the ability to
identify controllers which could be programmed to accept >32 bit
physical DMA addresses. The rest of fcd46b34425d should probably be
brought back as an optional instead of default feature.
Reported-by: Fabien Spindler <fabien.spindler@inria.fr>
Cc: <stable@vger.kernel.org> # 3.14+
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
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Result will be massaged to saner shape in the next commits. It is
ugly, no questions - the point of that one is to be a provably
equivalent transformation (and it might be worth splitting a bit
more).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... into trylocks and everything else. The latter (actual killing)
is __dentry_kill().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Commit 9c7e535fcc17 ("arm64: mm: Route pmd thp functions through pte
equivalents") changed the pmd manipulator and accessor functions to
convert the target pmd to a pte, process it with the pte functions, then
convert it back. Along the way, we gained support for PTE_WRITE, however
this is completely ignored by set_pmd_at, and so we fail to set the
PMD_SECT_RDONLY for PMDs, resulting in all sorts of lovely failures (like
CoW not working).
Partially reverting the offending commit (by making use of
PMD_SECT_RDONLY explicitly for pmd_{write,wrprotect,mkwrite} functions)
leads to further issues because pmd_write can then return potentially
incorrect values for page table entries marked as RDONLY, leading to
BUG_ON(pmd_write(entry)) tripping under some THP workloads.
This patch fixes the issue by routing set_pmd_at through set_pte_at,
which correctly takes the PTE_WRITE flag into account. Given that
THP mappings are always anonymous, the additional cache-flushing code
in __sync_icache_dcache won't impose any significant overhead as the
flush will be skipped.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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Handling calls to ->target_index() has got complex over time and might become
more complex. So, its better to take target_index() bits out in another routine
__target_index() for better code readability. Shouldn't have any functional
impact.
Tested-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
Pull sound fixes from Takashi Iwai:
"Just two small stable fixes: an HD-audio fix for the new Intel
chipsets and a PM handling fix in PCM dmaengine core"
* tag 'sound-3.15-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
ALSA: hda - Fix onboard audio on Intel H97/Z97 chipsets
ALSA: pcm_dmaengine: Add check during device suspend
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fix from Al Viro:
"Oh, well... Still nothing useful on that livelock (I had something
that looked kinda-sorta like a non-invasive solution, but it
deadlocks), so it's just Miklos' vmsplice fix for now"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vfs: fix vmplice_to_user()
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The content of /sys/devices/system/cpu/cpu*/online is still 1 for those
CPUs that the switcher has removed even though the global state in
/sys/devices/system/cpu/online is updated correctly.
It turns out that commit 0902a9044f ("Driver core: Use generic
offline/online for CPU offline/online") has changed the way those files
retrieve their content by relying on on the generic attribute handling
code. The switcher, by calling cpu_down() directly, bypasses this
handling and the attribute value doesn't get updated.
Fix this by calling device_offline()/device_online() instead.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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The current deadlock detection logic does not work reliably due to the
following early exit path:
/*
* Drop out, when the task has no waiters. Note,
* top_waiter can be NULL, when we are in the deboosting
* mode!
*/
if (top_waiter && (!task_has_pi_waiters(task) ||
top_waiter != task_top_pi_waiter(task)))
goto out_unlock_pi;
So this not only exits when the task has no waiters, it also exits
unconditionally when the current waiter is not the top priority waiter
of the task.
So in a nested locking scenario, it might abort the lock chain walk
and therefor miss a potential deadlock.
Simple fix: Continue the chain walk, when deadlock detection is
enabled.
We also avoid the whole enqueue, if we detect the deadlock right away
(A-A). It's an optimization, but also prevents that another waiter who
comes in after the detection and before the task has undone the damage
observes the situation and detects the deadlock and returns
-EDEADLOCK, which is wrong as the other task is not in a deadlock
situation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20140522031949.725272460@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Pull kvm fixes from Paolo Bonzini:
"Small fixes for x86, slightly larger fixes for PPC, and a forgotten
s390 patch. The PPC fixes are important because they fix breakage
that is new in 3.15"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: s390: announce irqfd capability
KVM: x86: disable master clock if TSC is reset during suspend
KVM: vmx: disable APIC virtualization in nested guests
KVM guest: Make pv trampoline code executable
KVM: PPC: Book3S: ifdef on CONFIG_KVM_BOOK3S_32_HANDLER for 32bit
KVM: PPC: Book3S HV: Add missing code for transaction reclaim on guest exit
KVM: PPC: Book3S: HV: make _PAGE_NUMA take effect
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git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc
Pull two powerpc fixes from Ben Herrenschmidt:
"Here's a pair of powerpc fixes for 3.15 which are also going to
stable.
One's a fix for building with newer binutils (the problem currently
only affects the BookE kernels but the affected macro might come back
into use on BookS platforms at any time). Unfortunately, the binutils
maintainer did a backward incompatible change to a construct that we
use so we have to add Makefile check.
The other one is a fix for CPUs getting stuck in kexec when running
single threaded. Since we routinely use kexec on power (including in
our newer bootloaders), I deemed that important enough"
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
powerpc, kexec: Fix "Processor X is stuck" issue during kexec from ST mode
powerpc: Fix 64 bit builds with binutils 2.24
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It can happen only when dentry_kill() is called with unlock_on_failure
equal to 0 - other callers had dentry pinned until the moment they've
got ->d_lock and DCACHE_DENTRY_KILLED is set only after lockref_mark_dead().
IOW, only one of three call sites of dentry_kill() might end up reaching
that code. Just move it there.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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