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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Mike reported that this recent commit:
3a47d5124a95 ("sched/fair: Fix fairness issue on migration")
... broke interactivity and the signal starvation test.
We have a proper fix series in the works but ran out of time for
v4.6, so revert the commit.
Reported-by: Mike Galbraith <efault@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
"A UP kernel cpufreq fix and a rt/dl scheduler corner case fix"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/rt, sched/dl: Don't push if task's scheduling class was changed
sched/fair: Fix !CONFIG_SMP kernel cpufreq governor breakage
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We got this warning:
WARNING: CPU: 1 PID: 2468 at kernel/sched/core.c:1161 set_task_cpu+0x1af/0x1c0
[...]
Call Trace:
dump_stack+0x63/0x87
__warn+0xd1/0xf0
warn_slowpath_null+0x1d/0x20
set_task_cpu+0x1af/0x1c0
push_dl_task.part.34+0xea/0x180
push_dl_tasks+0x17/0x30
__balance_callback+0x45/0x5c
__sched_setscheduler+0x906/0xb90
SyS_sched_setattr+0x150/0x190
do_syscall_64+0x62/0x110
entry_SYSCALL64_slow_path+0x25/0x25
This corresponds to:
WARN_ON_ONCE(p->state == TASK_RUNNING &&
p->sched_class == &fair_sched_class &&
(p->on_rq && !task_on_rq_migrating(p)))
It happens because in find_lock_later_rq(), the task whose scheduling
class was changed to fair class is still pushed away as if it were
a deadline task ...
So, check in find_lock_later_rq() after double_lock_balance(), if the
scheduling class of the deadline task was changed, break and retry.
Apply the same logic to RT tasks.
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Link: http://lkml.kernel.org/r/1462767091-1215-1-git-send-email-xlpang@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Allowing unprivileged kernel profiling lets any user dump follow kernel
control flow and dump kernel registers. This most likely allows trivial
kASLR bypassing, and it may allow other mischief as well. (Off the top
of my head, the PERF_SAMPLE_REGS_INTR output during /dev/urandom reads
could be quite interesting.)
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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... the comment clearly refers to wake_up_q(), and not
wake_up_list().
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Link: http://lkml.kernel.org/r/1462766290-28664-1-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Remove unused variable 'ret', and directly return 0.
Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1462441879-10092-1-git-send-email-falakreyaz@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The following commit:
34e2c555f3e1 ("cpufreq: Add mechanism for registering utilization update callbacks")
overlooked the fact that update_load_avg(), where CFS invokes cpufreq
utilization update callbacks, becomes an empty stub on UP kernels.
In consequence, if !CONFIG_SMP, cpufreq governors are never invoked
from CFS and they do not have a chance to evaluate CPU performace
levels and update them often enough.
Needless to say, things don't work as expected then.
Fix the problem by making the !CONFIG_SMP stub of update_load_avg()
invoke cpufreq update callbacks too.
Reported-by: Steve Muckle <steve.muckle@linaro.org>
Tested-by: Steve Muckle <steve.muckle@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Steve Muckle <steve.muckle@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux PM list <linux-pm@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Fixes: 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks)
Link: http://lkml.kernel.org/r/6282396.VVEdgVYxO3@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Ingo Molnar:
"This contains a single fix that fixes a nohz tick stopping bug when
mixed-poliocy SCHED_FIFO and SCHED_RR tasks are present on a runqueue"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
nohz/full, sched/rt: Fix missed tick-reenabling bug in sched_can_stop_tick()
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The comment in calculate_imbalance() was introduced in commit:
2dd73a4f09be ("[PATCH] sched: implement smpnice")
which described the logic as it was then, but a later commit:
b18855500fc4 ("sched/balancing: Fix 'local->avg_load > sds->avg_load' case in calculate_imbalance()")
.. complicated this logic some more so that the comment does not match anymore.
Update the comment to match the code.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1461958364-675-3-git-send-email-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Commit 8e7fbcbc22c1 ("sched: Remove stale power aware scheduling remnants
and dysfunctional knobs") deleted the power aware scheduling support.
This patch gets rid of the remaining power aware scheduling related
comments in the code as well.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1461958364-675-2-git-send-email-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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If we're accessing rq_clock() (e.g. in sched_avg_update()) we should
update the rq clock before calling cpu_load_update(), otherwise any
time calculations will be stale.
All other paths currently call update_rq_clock().
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1462304814-11715-1-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The max_idle_balance_cost and avg_idle values which are tracked and ar used to
capture short idle incidents, are not associated with schedstats, however the
information of these two values isn't printed out on !CONFIG_SCHEDSTATS kernels.
Fix this by moving the value printout out of the CONFIG_SCHEDSTATS section.
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1462250305-4523-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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__compute_runnable_contrib() uses a loop to compute sum, whereas a
table lookup can do it faster in a constant amount of time.
The program to generate the constants is located at:
Documentation/scheduler/sched-avg.txt
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Morten Rasmussen <morten.rasmussen@arm.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@arm.com
Cc: pjt@google.com
Link: http://lkml.kernel.org/r/1462226078-31904-2-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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SCHED_LOAD_SCALE
After cleaning up the sched metrics, there are two definitions that are
ambiguous and confusing: SCHED_LOAD_SHIFT and SCHED_LOAD_SHIFT.
Resolve this:
- Rename SCHED_LOAD_SHIFT to NICE_0_LOAD_SHIFT, which better reflects what
it is.
- Replace SCHED_LOAD_SCALE use with SCHED_CAPACITY_SCALE and remove SCHED_LOAD_SCALE.
Suggested-by: Ben Segall <bsegall@google.com>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: lizefan@huawei.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1459829551-21625-3-git-send-email-yuyang.du@intel.com
[ Rewrote the changelog and fixed the build on 32-bit kernels. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Integer metric needs fixed point arithmetic. In sched/fair, a few
metrics, e.g., weight, load, load_avg, util_avg, freq, and capacity,
may have different fixed point ranges, which makes their update and
usage error-prone.
In order to avoid the errors relating to the fixed point range, we
definie a basic fixed point range, and then formalize all metrics to
base on the basic range.
The basic range is 1024 or (1 << 10). Further, one can recursively
apply the basic range to have larger range.
Pointed out by Ben Segall, weight (visible to user, e.g., NICE-0 has
1024) and load (e.g., NICE_0_LOAD) have independent ranges, but they
must be well calibrated.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: lizefan@huawei.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1459829551-21625-2-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Mike ran into the low load resolution limitation on his big machine.
So reenable these bits; nobody could ever reproduce/analyze the
reported power usage claim and Google has been running with this for
years as well.
Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Tested-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The problem with the existing lock pinning is that each pin is of
value 1; this mean you can simply unpin if you know its pinned,
without having any extra information.
This scheme generates a random (16 bit) cookie for each pin and
requires this same cookie to unpin. This means you have to keep the
cookie in context.
No objsize difference for !LOCKDEP kernels.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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In order to be able to pass around more than just the IRQ flags in the
future, add a rq_flags structure.
No difference in code generation for the x86_64-defconfig build I
tested.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Its a rather large function, inline doesn't seems to make much sense:
$ size defconfig-build/kernel/sched/core.o{.orig,}
text data bss dec hex filename
56533 21037 2320 79890 13812 defconfig-build/kernel/sched/core.o.orig
55733 21037 2320 79090 134f2 defconfig-build/kernel/sched/core.o
The 'perf bench sched messaging' micro-benchmark shows a visible improvement
of 4-5%:
$ for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo performance > $i ; done
$ perf stat --null --repeat 25 -- perf bench sched messaging -g 40 -l 5000
pre:
4.582798193 seconds time elapsed ( +- 1.41% )
4.733374877 seconds time elapsed ( +- 2.10% )
4.560955136 seconds time elapsed ( +- 1.43% )
4.631062303 seconds time elapsed ( +- 1.40% )
post:
4.364765213 seconds time elapsed ( +- 0.91% )
4.454442734 seconds time elapsed ( +- 1.18% )
4.448893817 seconds time elapsed ( +- 1.41% )
4.424346872 seconds time elapsed ( +- 0.97% )
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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applying new changes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
"Chunyu Hu noticed that if one writes into the trigger files within the
ftrace subsystem of events that it can cause an oops. This file is
only writable by root, but still is a bug that needs to be fixed"
* tag 'trace-fixes-v4.6-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Don't display trigger file for events that can't be enabled
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Currently register functions for events will be called
through the 'reg' field of event class directly without
any check when seting up triggers.
Triggers for events that don't support register through
debug fs (events under events/ftrace are for trace-cmd to
read event format, and most of them don't have a register
function except events/ftrace/functionx) can't be enabled
at all, and an oops will be hit when setting up trigger
for those events, so just not creating them is an easy way
to avoid the oops.
Link: http://lkml.kernel.org/r/1462275274-3911-1-git-send-email-chuhu@redhat.com
Cc: stable@vger.kernel.org # 3.14+
Fixes: 85f2b08268c01 ("tracing: Add basic event trigger framework")
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Pull networking fixes from David Miller:
1) MODULE_FIRMWARE firmware string not correct for iwlwifi 8000 chips,
from Sara Sharon.
2) Fix SKB size checks in batman-adv stack on receive, from Sven
Eckelmann.
3) Leak fix on mac80211 interface add error paths, from Johannes Berg.
4) Cannot invoke napi_disable() with BH disabled in myri10ge driver,
fix from Stanislaw Gruszka.
5) Fix sign extension problem when computing feature masks in
net_gso_ok(), from Marcelo Ricardo Leitner.
6) lan78xx driver doesn't count packets and packet lengths in its
statistics properly, fix from Woojung Huh.
7) Fix the buffer allocation sizes in pegasus USB driver, from Petko
Manolov.
8) Fix refcount overflows in bpf, from Alexei Starovoitov.
9) Unified dst cache handling introduced a preempt warning in
ip_tunnel, fix by resetting rather then setting the cached route.
From Paolo Abeni.
10) Listener hash collision test fix in soreuseport, from Craig Gallak
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (47 commits)
gre: do not pull header in ICMP error processing
net: Implement net_dbg_ratelimited() for CONFIG_DYNAMIC_DEBUG case
tipc: only process unicast on intended node
cxgb3: fix out of bounds read
net/smscx5xx: use the device tree for mac address
soreuseport: Fix TCP listener hash collision
net: l2tp: fix reversed udp6 checksum flags
ip_tunnel: fix preempt warning in ip tunnel creation/updating
samples/bpf: fix trace_output example
bpf: fix check_map_func_compatibility logic
bpf: fix refcnt overflow
drivers: net: cpsw: use of_phy_connect() in fixed-link case
dt: cpsw: phy-handle, phy_id, and fixed-link are mutually exclusive
drivers: net: cpsw: don't ignore phy-mode if phy-handle is used
drivers: net: cpsw: fix segfault in case of bad phy-handle
drivers: net: cpsw: fix parsing of phy-handle DT property in dual_emac config
MAINTAINERS: net: Change maintainer for GRETH 10/100/1G Ethernet MAC device driver
gre: reject GUE and FOU in collect metadata mode
pegasus: fixes reported packet length
pegasus: fixes URB buffer allocation size;
...
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Merge fixes from Andrew Morton:
"20 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
Documentation/sysctl/vm.txt: update numa_zonelist_order description
lib/stackdepot.c: allow the stack trace hash to be zero
rapidio: fix potential NULL pointer dereference
mm/memory-failure: fix race with compound page split/merge
ocfs2/dlm: return zero if deref_done message is successfully handled
Ananth has moved
kcov: don't profile branches in kcov
kcov: don't trace the code coverage code
mm: wake kcompactd before kswapd's short sleep
.mailmap: add Frank Rowand
mm/hwpoison: fix wrong num_poisoned_pages accounting
mm: call swap_slot_free_notify() with page lock held
mm: vmscan: reclaim highmem zone if buffer_heads is over limit
numa: fix /proc/<pid>/numa_maps for THP
mm/huge_memory: replace VM_NO_THP VM_BUG_ON with actual VMA check
mailmap: fix Krzysztof Kozlowski's misspelled name
thp: keep huge zero page pinned until tlb flush
mm: exclude HugeTLB pages from THP page_mapped() logic
kexec: export OFFSET(page.compound_head) to find out compound tail page
kexec: update VMCOREINFO for compound_order/dtor
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
"x86 PMU driver fixes plus a core code race fix"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel: Fix incorrect lbr_sel_mask value
perf/x86/intel/pt: Don't die on VMXON
perf/core: Fix perf_event_open() vs. execve() race
perf/x86/amd: Set the size of event map array to PERF_COUNT_HW_MAX
perf/core: Make sysctl_perf_cpu_time_max_percent conform to documentation
perf/x86/intel/rapl: Add missing Haswell model
perf/x86/intel: Add model number for Skylake Server to perf
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
"Two lockdep fixes"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
lockdep: Fix lock_chain::base size
locking/lockdep: Fix ->irq_context calculation
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Profiling 'if' statements in __sanitizer_cov_trace_pc() leads to
unbound recursion and crash:
__sanitizer_cov_trace_pc() ->
ftrace_likely_update ->
__sanitizer_cov_trace_pc() ...
Define DISABLE_BRANCH_PROFILING to disable this tracer.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kcov causes the compiler to add a call to __sanitizer_cov_trace_pc() in
every basic block. Ftrace patches in a call to _mcount() to each
function it has annotated.
Letting these mechanisms annotate each other is a bad thing. Break the
loop by adding 'notrace' to __sanitizer_cov_trace_pc() so that ftrace
won't try to patch this code.
This patch lets arm64 with KCOV and STACK_TRACER boot.
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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PageAnon() always look at head page to check PAGE_MAPPING_ANON and tail
page's page->mapping has just a poisoned data since commit 1c290f642101
("mm: sanitize page->mapping for tail pages").
If makedumpfile checks page->mapping of a compound tail page to
distinguish anonymous page as usual, it must fail in newer kernel. So
it's necessary to export OFFSET(page.compound_head) to avoid checking
compound tail pages.
The problem is that unnecessary hugepages won't be removed from a dump
file in kernels 4.5.x and later. This means that extra disk space would
be consumed. It's a problem, but not critical.
Signed-off-by: Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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makedumpfile refers page.lru.next to get the order of compound pages for
page filtering.
However, now the order is stored in page.compound_order, hence
VMCOREINFO should be updated to export the offset of
page.compound_order.
The fact is, page.compound_order was introduced already in kernel 4.0,
but the offset of it was the same as page.lru.next until kernel 4.3, so
this was not actual problem.
The above can be said also for page.lru.prev and page.compound_dtor,
it's necessary to detect hugetlbfs pages. Further, the content was
changed from direct address to the ID which means dtor.
The problem is that unnecessary hugepages won't be removed from a dump
file in kernels 4.4.x and later. This means that extra disk space would
be consumed. It's a problem, but not critical.
Signed-off-by: Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The commit 35578d798400 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter")
introduced clever way to check bpf_helper<->map_type compatibility.
Later on commit a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") adjusted
the logic and inadvertently broke it.
Get rid of the clever bool compare and go back to two-way check
from map and from helper perspective.
Fixes: a43eec304259 ("bpf: introduce bpf_perf_event_output() helper")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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On a system with >32Gbyte of phyiscal memory and infinite RLIMIT_MEMLOCK,
the malicious application may overflow 32-bit bpf program refcnt.
It's also possible to overflow map refcnt on 1Tb system.
Impose 32k hard limit which means that the same bpf program or
map cannot be shared by more than 32k processes.
Fixes: 1be7f75d1668 ("bpf: enable non-root eBPF programs")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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By default, this is the same thing as switch_mm().
x86 will override it as an optimization.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/df401df47bdd6be3e389c6f1e3f5310d70e81b2c.1461688545.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Sometimes delta_exec is 0 due to update_curr() is called multiple times,
this is captured by:
u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
This patch optimizes the cpufreq update kicker by bailing out when nothing
changed, it will benefit the upcoming schedutil, since otherwise it will
(over)react to the special util/max combination.
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1461316044-9520-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Jann reported that the ptrace_may_access() check in
find_lively_task_by_vpid() is racy against exec().
Specifically:
perf_event_open() execve()
ptrace_may_access()
commit_creds()
... if (get_dumpable() != SUID_DUMP_USER)
perf_event_exit_task();
perf_install_in_context()
would result in installing a counter across the creds boundary.
Fix this by wrapping lots of perf_event_open() in cred_guard_mutex.
This should be fine as perf_event_exit_task() is already called with
cred_guard_mutex held, so all perf locks already nest inside it.
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Chris Metcalf reported a that sched_can_stop_tick() sometimes fails to
re-enable the tick.
His observed problem is that rq->cfs.nr_running can be 1 even though
there are multiple runnable CFS tasks. This happens in the cgroup
case, in which case cfs.nr_running is the number of runnable entities
for that level.
If there is a single runnable cgroup (which can have an arbitrary
number of runnable child entries itself) rq->cfs.nr_running will be 1.
However, looking at that function I think there's more problems with it.
It seems to assume that if there's FIFO tasks, those will run. This is
incorrect. The FIFO task can have a lower prio than an RR task, in which
case the RR task will run.
So the whole fifo_nr_running test seems misplaced, it should go after
the rr_nr_running tests. That is, only if !rr_nr_running, can we use
fifo_nr_running like this.
Reported-by: Chris Metcalf <cmetcalf@mellanox.com>
Tested-by: Chris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Fixes: 76d92ac305f2 ("sched: Migrate sched to use new tick dependency mask model")
Link: http://lkml.kernel.org/r/20160421160315.GK24771@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fix from Tejun Heo:
"So, it turns out we had a silly bug in the most fundamental part of
workqueue for a very long time. AFAICS, this dates back to pre-git
era and has quite likely been there from the time workqueue was first
introduced.
A work item uses its PENDING bit to synchronize multiple queuers.
Anyone who wins the PENDING bit owns the pending state of the work
item. Whether a queuer wins or loses the race, one thing should be
guaranteed - there will soon be at least one execution of the work
item - where "after" means that the execution instance would be able
to see all the changes that the queuer has made prior to the queueing
attempt.
Unfortunately, we were missing a smp_mb() after clearing PENDING for
execution, so nothing guaranteed visibility of the changes that a
queueing loser has made, which manifested as a reproducible blk-mq
stall.
Lots of kudos to Roman for debugging the problem. The patch for
-stable is the minimal one. For v3.7, Peter is working on a patch to
make the code path slightly more efficient and less fragile"
* 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: fix ghost PENDING flag while doing MQ IO
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"Two patches to fix a deadlock which can be easily triggered if memcg
charge moving is used.
This bug was introduced while converting threadgroup locking to a
global percpu_rwsem and is caused by cgroup controller task migration
path depending on the ability to create new kthreads. cpuset had a
similar issue which was fixed by performing heavy-lifting operations
asynchronous to task migration. The two patches fix the same issue in
memcg in a similar way. The first patch makes the mechanism generic
and the second relocates memcg charge moving outside the migration
path.
Given that we don't want to perform heavy operations while
writelocking threadgroup lock anyway, moving them out of the way is a
desirable solution. One thing to note is that the problem was
difficult to debug because lockdep couldn't figure out the deadlock
condition. Looking into how to improve that"
* 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
memcg: relocate charge moving from ->attach to ->post_attach
cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback
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Pull networking fixes from David Miller:
1) Handle v4/v6 mixed sockets properly in soreuseport, from Craig
Gallak.
2) Bug fixes for the new macsec facility (missing kmalloc NULL checks,
missing locking around netdev list traversal, etc.) from Sabrina
Dubroca.
3) Fix handling of host routes on ifdown in ipv6, from David Ahern.
4) Fix double-fdput in bpf verifier. From Jann Horn.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (31 commits)
bpf: fix double-fdput in replace_map_fd_with_map_ptr()
net: ipv6: Delete host routes on an ifdown
Revert "ipv6: Revert optional address flusing on ifdown."
net/mlx4_en: fix spurious timestamping callbacks
net: dummy: remove note about being Y by default
cxgbi: fix uninitialized flowi6
ipv6: Revert optional address flusing on ifdown.
ipv4/fib: don't warn when primary address is missing if in_dev is dead
net/mlx5: Add pci shutdown callback
net/mlx5_core: Remove static from local variable
net/mlx5e: Use vport MTU rather than physical port MTU
net/mlx5e: Fix minimum MTU
net/mlx5e: Device's mtu field is u16 and not int
net/mlx5_core: Add ConnectX-5 to list of supported devices
net/mlx5e: Fix MLX5E_100BASE_T define
net/mlx5_core: Fix soft lockup in steering error flow
qlcnic: Update version to 5.3.64
net: stmmac: socfpga: Remove re-registration of reset controller
macsec: fix netlink attribute validation
macsec: add missing macsec prefix in uapi
...
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When bpf(BPF_PROG_LOAD, ...) was invoked with a BPF program whose bytecode
references a non-map file descriptor as a map file descriptor, the error
handling code called fdput() twice instead of once (in __bpf_map_get() and
in replace_map_fd_with_map_ptr()). If the file descriptor table of the
current task is shared, this causes f_count to be decremented too much,
allowing the struct file to be freed while it is still in use
(use-after-free). This can be exploited to gain root privileges by an
unprivileged user.
This bug was introduced in
commit 0246e64d9a5f ("bpf: handle pseudo BPF_LD_IMM64 insn"), but is only
exploitable since
commit 1be7f75d1668 ("bpf: enable non-root eBPF programs") because
previously, CAP_SYS_ADMIN was required to reach the vulnerable code.
(posted publicly according to request by maintainer)
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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|
The bug in a workqueue leads to a stalled IO request in MQ ctx->rq_list
with the following backtrace:
[ 601.347452] INFO: task kworker/u129:5:1636 blocked for more than 120 seconds.
[ 601.347574] Tainted: G O 4.4.5-1-storage+ #6
[ 601.347651] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 601.348142] kworker/u129:5 D ffff880803077988 0 1636 2 0x00000000
[ 601.348519] Workqueue: ibnbd_server_fileio_wq ibnbd_dev_file_submit_io_worker [ibnbd_server]
[ 601.348999] ffff880803077988 ffff88080466b900 ffff8808033f9c80 ffff880803078000
[ 601.349662] ffff880807c95000 7fffffffffffffff ffffffff815b0920 ffff880803077ad0
[ 601.350333] ffff8808030779a0 ffffffff815b01d5 0000000000000000 ffff880803077a38
[ 601.350965] Call Trace:
[ 601.351203] [<ffffffff815b0920>] ? bit_wait+0x60/0x60
[ 601.351444] [<ffffffff815b01d5>] schedule+0x35/0x80
[ 601.351709] [<ffffffff815b2dd2>] schedule_timeout+0x192/0x230
[ 601.351958] [<ffffffff812d43f7>] ? blk_flush_plug_list+0xc7/0x220
[ 601.352208] [<ffffffff810bd737>] ? ktime_get+0x37/0xa0
[ 601.352446] [<ffffffff815b0920>] ? bit_wait+0x60/0x60
[ 601.352688] [<ffffffff815af784>] io_schedule_timeout+0xa4/0x110
[ 601.352951] [<ffffffff815b3a4e>] ? _raw_spin_unlock_irqrestore+0xe/0x10
[ 601.353196] [<ffffffff815b093b>] bit_wait_io+0x1b/0x70
[ 601.353440] [<ffffffff815b056d>] __wait_on_bit+0x5d/0x90
[ 601.353689] [<ffffffff81127bd0>] wait_on_page_bit+0xc0/0xd0
[ 601.353958] [<ffffffff81096db0>] ? autoremove_wake_function+0x40/0x40
[ 601.354200] [<ffffffff81127cc4>] __filemap_fdatawait_range+0xe4/0x140
[ 601.354441] [<ffffffff81127d34>] filemap_fdatawait_range+0x14/0x30
[ 601.354688] [<ffffffff81129a9f>] filemap_write_and_wait_range+0x3f/0x70
[ 601.354932] [<ffffffff811ced3b>] blkdev_fsync+0x1b/0x50
[ 601.355193] [<ffffffff811c82d9>] vfs_fsync_range+0x49/0xa0
[ 601.355432] [<ffffffff811cf45a>] blkdev_write_iter+0xca/0x100
[ 601.355679] [<ffffffff81197b1a>] __vfs_write+0xaa/0xe0
[ 601.355925] [<ffffffff81198379>] vfs_write+0xa9/0x1a0
[ 601.356164] [<ffffffff811c59d8>] kernel_write+0x38/0x50
The underlying device is a null_blk, with default parameters:
queue_mode = MQ
submit_queues = 1
Verification that nullb0 has something inflight:
root@pserver8:~# cat /sys/block/nullb0/inflight
0 1
root@pserver8:~# find /sys/block/nullb0/mq/0/cpu* -name rq_list -print -exec cat {} \;
...
/sys/block/nullb0/mq/0/cpu2/rq_list
CTX pending:
ffff8838038e2400
...
During debug it became clear that stalled request is always inserted in
the rq_list from the following path:
save_stack_trace_tsk + 34
blk_mq_insert_requests + 231
blk_mq_flush_plug_list + 281
blk_flush_plug_list + 199
wait_on_page_bit + 192
__filemap_fdatawait_range + 228
filemap_fdatawait_range + 20
filemap_write_and_wait_range + 63
blkdev_fsync + 27
vfs_fsync_range + 73
blkdev_write_iter + 202
__vfs_write + 170
vfs_write + 169
kernel_write + 56
So blk_flush_plug_list() was called with from_schedule == true.
If from_schedule is true, that means that finally blk_mq_insert_requests()
offloads execution of __blk_mq_run_hw_queue() and uses kblockd workqueue,
i.e. it calls kblockd_schedule_delayed_work_on().
That means, that we race with another CPU, which is about to execute
__blk_mq_run_hw_queue() work.
Further debugging shows the following traces from different CPUs:
CPU#0 CPU#1
---------------------------------- -------------------------------
reqeust A inserted
STORE hctx->ctx_map[0] bit marked
kblockd_schedule...() returns 1
<schedule to kblockd workqueue>
request B inserted
STORE hctx->ctx_map[1] bit marked
kblockd_schedule...() returns 0
*** WORK PENDING bit is cleared ***
flush_busy_ctxs() is executed, but
bit 1, set by CPU#1, is not observed
As a result request B pended forever.
This behaviour can be explained by speculative LOAD of hctx->ctx_map on
CPU#0, which is reordered with clear of PENDING bit and executed _before_
actual STORE of bit 1 on CPU#1.
The proper fix is an explicit full barrier <mfence>, which guarantees
that clear of PENDING bit is to be executed before all possible
speculative LOADS or STORES inside actual work function.
Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Gioh Kim <gi-oh.kim@profitbricks.com>
Cc: Michael Wang <yun.wang@profitbricks.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
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cgroup_subsys->post_attach callback
Since e93ad19d0564 ("cpuset: make mm migration asynchronous"), cpuset
kicks off asynchronous NUMA node migration if necessary during task
migration and flushes it from cpuset_post_attach_flush() which is
called at the end of __cgroup_procs_write(). This is to avoid
performing migration with cgroup_threadgroup_rwsem write-locked which
can lead to deadlock through dependency on kworker creation.
memcg has a similar issue with charge moving, so let's convert it to
an official callback rather than the current one-off cpuset specific
function. This patch adds cgroup_subsys->post_attach callback and
makes cpuset register cpuset_post_attach_flush() as its ->post_attach.
The conversion is mostly one-to-one except that the new callback is
called under cgroup_mutex. This is to guarantee that no other
migration operations are started before ->post_attach callbacks are
finished. cgroup_mutex is one of the outermost mutex in the system
and has never been and shouldn't be a problem. We can add specialized
synchronization around __cgroup_procs_write() but I don't think
there's any noticeable benefit.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org> # 4.4+ prerequisite for the next patch
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|
'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf, cpu hotplug and timer fixes from Ingo Molnar:
"perf:
- A single tooling fix for a user-triggerable segfault.
CPU hotplug:
- Fix a CPU hotplug corner case regression, introduced by the recent
hotplug rework
timers:
- Fix a boot hang in the ARM based Tango SoC clocksource driver"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf intel-pt: Fix segfault tracing transactions
* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu/hotplug: Fix rollback during error-out in __cpu_disable()
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource/drivers/tango-xtal: Fix boot hang due to incorrect test
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|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
"Misc fixes:
pvqspinlocks:
- an instrumentation fix
futexes:
- preempt-count vs pagefault_disable decouple corner case fix
- futex requeue plist race window fix
- futex UNLOCK_PI transaction fix for a corner case"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic()
futex: Acknowledge a new waiter in counter before plist
futex: Handle unlock_pi race gracefully
locking/pvqspinlock: Fix division by zero in qstat_read()
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|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq fixes from Ingo Molnar:
"A core irq affinity masks related fix and a MIPS irqchip driver fix"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/mips-gic: Don't overrun pcpu_masks array
genirq: Dont allow affinity mask to be updated on IPIs
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|
I got a minus(very big) dl_b->total_bw during my deadline tests.
# grep dl /proc/sched_debug
dl_rq[0]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -222297900
Something unusual must have happened.
After some digging, I finally noticed that when changing a deadline
task to normal(cfs), and changing it back to deadline immediately,
after it died, we will got the wrong dl_bw->total_bw.
The root cause is in dl_overflow(), it has:
if (new_bw == p->dl.dl_bw)
return 0;
1) When a deadline task is changed to !deadline task, it will start
dl timer in switched_from_dl(), and retain previous deadline parameter
till the timer expires.
2) If we change it back to deadline with the same bandwidth parameter
before the timer expires, as it keeps the old bandwidth although it
is not a deadline task. dl_overflow() simply returns success without
updating the right data, and got the wrong dl_bw->total_bw.
The solution is simple, if @p is not deadline, don't return.
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1460636368-1993-1-git-send-email-xlpang@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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|
Some code in CPU load update only concern NO_HZ configs but it is
built on all configurations. When NO_HZ isn't built, that code is harmless
but just happens to take some useless ressources in CPU and memory:
1) one useless field in struct rq
2) jiffies record on every tick that is never used (cpu_load_update_periodic)
3) decay_load_missed is called two times on every tick to eventually
return immediately with no action taken. And that function is dead
code.
For pure optimization purposes, lets conditionally build the NO_HZ
related code.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1461080211-16271-1-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Ticks can happen while the CPU is in dynticks-idle or dynticks-singletask
mode. In fact "nohz" or "dynticks" only mean that we exit the periodic
mode and we try to minimize the ticks as much as possible. The nohz
subsystem uses a confusing terminology with the internal state
"ts->tick_stopped" which is also available through its public interface
with tick_nohz_tick_stopped(). This is a misnomer as the tick is instead
reduced with the best effort rather than stopped. In the best case the
tick can indeed be actually stopped but there is no guarantee about that.
If a timer needs to fire one second later, a tick will fire while the
CPU is in nohz mode and this is a very common scenario.
Now this confusion happens to be a problem with CPU load updates:
cpu_load_update_active() doesn't handle nohz ticks correctly because it
assumes that ticks are completely stopped in nohz mode and that
cpu_load_update_active() can't be called in dynticks mode. When that
happens, the whole previous tickless load is ignored and the function
just records the load for the current tick, ignoring potentially long
idle periods behind.
In order to solve this, we could account the current load for the
previous nohz time but there is a risk that we account the load of a
task that got freshly enqueued for the whole nohz period.
So instead, lets record the dynticks load on nohz frame entry so we know
what to record in case of nohz ticks, then use this record to account
the tickless load on nohz ticks and nohz frame end.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1460555812-25375-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The CPU load update related functions have a weak naming convention
currently, starting with update_cpu_load_*() which isn't ideal as
"update" is a very generic concept.
Since two of these functions are public already (and a third is to come)
that's enough to introduce a more conventional naming scheme. So let's
do the following rename instead:
update_cpu_load_*() -> cpu_load_update_*()
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1460555812-25375-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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