Since sysctl_hung_task_warnings == -1 is allowed (infinite warnings),
commit 48a6d64eda ("hung_task: allow hung_task_panic when
hung_task_warnings is 0") should decrement it only when it is not -1.
This prevents the kernel from ceasing warnings after the first
4294967295 ;)
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: John Siddle <jsiddle@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This limitation came with the reason to remove "another way for
malicious code to obscure a compromised program and masquerade as a
benign process" by allowing "security-concious program can use this
prctl once during its early initialization to ensure the prctl cannot
later be abused for this purpose":
http://marc.info/?l=linux-kernel&m=133160684517468&w=2
This explanation doesn't look sufficient. The only thing "exe" link is
indicating is the file, used to execve, which is basically nothing and
not reliable immediately after process has returned from execve system
call.
Moreover, to use this feture, all the mappings to previous exe file have
to be unmapped and all the new exe file permissions must be satisfied.
Which means, that changing exe link is very similar to calling execve on
the binary.
The need to remove this limitations comes from migration of NFS mount
point, which is not accessible during restore and replaced by other file
system. Because of this exe link has to be changed twice.
[akpm@linux-foundation.org: fix up comment]
Link: http://lkml.kernel.org/r/20160927153755.9337.69650.stgit@localhost.localdomain
Signed-off-by: Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When commit fbae2d44aa ("kthread: add kthread_create_worker*()")
introduced some kthread_create_...() functions which were taking
printf-like parametter, it introduced __printf attributes to some
functions (e.g. kthread_create_worker()). Nevertheless some new
functions were forgotten (they have been detected thanks to
-Wmissing-format-attribute warning flag).
Add the missing __printf attributes to the newly-introduced functions in
order to detect formatting issues at build-time with -Wformat flag.
Link: http://lkml.kernel.org/r/20161126193543.22672-1-nicolas.iooss_linux@m4x.org
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 265a5b7ee3 ("kprobes/trace: Fix kprobe selftest for gcc 4.6")
has added __used attribute to kprobe_trace_selftest_target to ensure
that the method is listed in kallsyms table.
However, even though the method remains in the kernel image, the actual
call is optimized away as there are no side effects and the return value
is never checked.
Add a return value check and a 'noinline' attribute to ensure that an
inlined copy of the method is not used by the caller. Also add checks
that verify that the kprobe was really hit, as at the moment the tests
show positive results despite the test method being optimized away.
Finally, add __init annotations to find_trace_probe_file() and
kprobe_trace_selftest_target() as they are only called from within an
__init method.
Link: http://lkml.kernel.org/r/1481293178-3128-2-git-send-email-marcin.nowakowski@imgtec.com
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull x86 asm updates from Ingo Molnar:
"The main changes in this development cycle were:
- a large number of call stack dumping/printing improvements: higher
robustness, better cross-context dumping, improved output, etc.
(Josh Poimboeuf)
- vDSO getcpu() performance improvement for future Intel CPUs with
the RDPID instruction (Andy Lutomirski)
- add two new Intel AVX512 features and the CPUID support
infrastructure for it: AVX512IFMA and AVX512VBMI. (Gayatri Kammela,
He Chen)
- more copy-user unification (Borislav Petkov)
- entry code assembly macro simplifications (Alexander Kuleshov)
- vDSO C/R support improvements (Dmitry Safonov)
- misc fixes and cleanups (Borislav Petkov, Paul Bolle)"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
scripts/decode_stacktrace.sh: Fix address line detection on x86
x86/boot/64: Use defines for page size
x86/dumpstack: Make stack name tags more comprehensible
selftests/x86: Add test_vdso to test getcpu()
x86/vdso: Use RDPID in preference to LSL when available
x86/dumpstack: Handle NULL stack pointer in show_trace_log_lvl()
x86/cpufeatures: Enable new AVX512 cpu features
x86/cpuid: Provide get_scattered_cpuid_leaf()
x86/cpuid: Cleanup cpuid_regs definitions
x86/copy_user: Unify the code by removing the 64-bit asm _copy_*_user() variants
x86/unwind: Ensure stack grows down
x86/vdso: Set vDSO pointer only after success
x86/prctl/uapi: Remove #ifdef for CHECKPOINT_RESTORE
x86/unwind: Detect bad stack return address
x86/dumpstack: Warn on stack recursion
x86/unwind: Warn on bad frame pointer
x86/decoder: Use stderr if insn sanity test fails
x86/decoder: Use stdout if insn decoder test is successful
mm/page_alloc: Remove kernel address exposure in free_reserved_area()
x86/dumpstack: Remove raw stack dump
...
Pull hotplug API fix from Ingo Molnar:
"Late breaking fix from the v4.9 cycle: fix a hotplug register/
unregister notifier API asymmetry bug that can cause kernel warnings
(and worse) with certain Kconfig combinations"
* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hotplug: Make register and unregister notifier API symmetric
Pull scheduler updates from Ingo Molnar:
"The main scheduler changes in this cycle were:
- support Intel Turbo Boost Max Technology 3.0 (TBM3) by introducig a
notion of 'better cores', which the scheduler will prefer to
schedule single threaded workloads on. (Tim Chen, Srinivas
Pandruvada)
- enhance the handling of asymmetric capacity CPUs further (Morten
Rasmussen)
- improve/fix load handling when moving tasks between task groups
(Vincent Guittot)
- simplify and clean up the cputime code (Stanislaw Gruszka)
- improve mass fork()ed task spread a.k.a. hackbench speedup (Vincent
Guittot)
- make struct kthread kmalloc()ed and related fixes (Oleg Nesterov)
- add uaccess atomicity debugging (when using access_ok() in the
wrong context), under CONFIG_DEBUG_ATOMIC_SLEEP=y (Peter Zijlstra)
- implement various fixes, cleanups and other enhancements (Daniel
Bristot de Oliveira, Martin Schwidefsky, Rafael J. Wysocki)"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
sched/core: Use load_avg for selecting idlest group
sched/core: Fix find_idlest_group() for fork
kthread: Don't abuse kthread_create_on_cpu() in __kthread_create_worker()
kthread: Don't use to_live_kthread() in kthread_[un]park()
kthread: Don't use to_live_kthread() in kthread_stop()
Revert "kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function"
kthread: Make struct kthread kmalloc'ed
x86/uaccess, sched/preempt: Verify access_ok() context
sched/x86: Make CONFIG_SCHED_MC_PRIO=y easier to enable
sched/x86: Change CONFIG_SCHED_ITMT to CONFIG_SCHED_MC_PRIO
x86/sched: Use #include <linux/mutex.h> instead of #include <asm/mutex.h>
cpufreq/intel_pstate: Use CPPC to get max performance
acpi/bus: Set _OSC for diverse core support
acpi/bus: Enable HWP CPPC objects
x86/sched: Add SD_ASYM_PACKING flags to x86 ITMT CPU
x86/sysctl: Add sysctl for ITMT scheduling feature
x86: Enable Intel Turbo Boost Max Technology 3.0
x86/topology: Define x86's arch_update_cpu_topology
sched: Extend scheduler's asym packing
sched/fair: Clean up the tunable parameter definitions
...
* pm-cpuidle:
cpuidle: Add a kerneldoc comment to cpuidle_use_deepest_state()
cpuidle: fix improper return value on error
intel_idle: Convert to hotplug state machine
intel_idle: Remove superfluous SMP fuction call
MAINTAINERS: Add Jacob Pan as a new intel_idle maintainer
MAINTAINERS: Add bug tracking system location entries for cpuidle
x86/intel_idle: Add Knights Mill CPUID
x86/intel_idle: Add CPU model 0x4a (Atom Z34xx series)
thermal/intel_powerclamp: stop sched tick in forced idle
thermal/intel_powerclamp: Convert to CPU hotplug state
thermal/intel_powerclamp: Convert the kthread to kthread worker API
thermal/intel_powerclamp: Remove duplicated code that starts the kthread
sched/idle: Add support for tasks that inject idle
cpuidle: Allow enforcing deepest idle state selection
cpuidle/powernv: staticise powernv_idle_driver
cpuidle: dt: assign ->enter_freeze to same as ->enter callback function
cpuidle: governors: Remove remaining old module code
* pm-cpufreq: (51 commits)
Documentation: intel_pstate: Document HWP energy/performance hints
cpufreq: intel_pstate: Support for energy performance hints with HWP
cpufreq: intel_pstate: Add locking around HWP requests
cpufreq: ondemand: Set MIN_FREQUENCY_UP_THRESHOLD to 1
cpufreq: intel_pstate: Add Knights Mill CPUID
MAINTAINERS: Add bug tracking system location entry for cpufreq
cpufreq: dt: Add support for zx296718
cpufreq: acpi-cpufreq: drop rdmsr_on_cpus() usage
cpufreq: acpi-cpufreq: Convert to hotplug state machine
cpufreq: intel_pstate: fix intel_pstate_exit_perf_limits() prototype
cpufreq: intel_pstate: Set EPP/EPB to 0 in performance mode
cpufreq: schedutil: Rectify comment in sugov_irq_work() function
cpufreq: intel_pstate: increase precision of performance limits
cpufreq: intel_pstate: round up min_perf limits
cpufreq: Make cpufreq_update_policy() void
ACPI / processor: Make acpi_processor_ppc_has_changed() void
cpufreq: Avoid using inactive policies
cpufreq: intel_pstate: Generic governors support
cpufreq: intel_pstate: Request P-states control from SMM if needed
cpufreq: dt: Add support for r8a7743 and r8a7745
...
Pull locking updates from Ingo Molnar:
"The tree got pretty big in this development cycle, but the net effect
is pretty good:
115 files changed, 673 insertions(+), 1522 deletions(-)
The main changes were:
- Rework and generalize the mutex code to remove per arch mutex
primitives. (Peter Zijlstra)
- Add vCPU preemption support: add an interface to query the
preemption status of vCPUs and use it in locking primitives - this
optimizes paravirt performance. (Pan Xinhui, Juergen Gross,
Christian Borntraeger)
- Introduce cpu_relax_yield() and remov cpu_relax_lowlatency() to
clean up and improve the s390 lock yielding machinery and its core
kernel impact. (Christian Borntraeger)
- Micro-optimize mutexes some more. (Waiman Long)
- Reluctantly add the to-be-deprecated mutex_trylock_recursive()
interface on a temporary basis, to give the DRM code more time to
get rid of its locking hacks. Any other users will be NAK-ed on
sight. (We turned off the deprecation warning for the time being to
not pollute the build log.) (Peter Zijlstra)
- Improve the rtmutex code a bit, in light of recent long lived
bugs/races. (Thomas Gleixner)
- Misc fixes, cleanups"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
x86/paravirt: Fix bool return type for PVOP_CALL()
x86/paravirt: Fix native_patch()
locking/ww_mutex: Use relaxed atomics
locking/rtmutex: Explain locking rules for rt_mutex_proxy_unlock()/init_proxy_locked()
locking/rtmutex: Get rid of RT_MUTEX_OWNER_MASKALL
x86/paravirt: Optimize native pv_lock_ops.vcpu_is_preempted()
locking/mutex: Break out of expensive busy-loop on {mutex,rwsem}_spin_on_owner() when owner vCPU is preempted
locking/osq: Break out of spin-wait busy waiting loop for a preempted vCPU in osq_lock()
Documentation/virtual/kvm: Support the vCPU preemption check
x86/xen: Support the vCPU preemption check
x86/kvm: Support the vCPU preemption check
x86/kvm: Support the vCPU preemption check
kvm: Introduce kvm_write_guest_offset_cached()
locking/core, x86/paravirt: Implement vcpu_is_preempted(cpu) for KVM and Xen guests
locking/spinlocks, s390: Implement vcpu_is_preempted(cpu)
locking/core, powerpc: Implement vcpu_is_preempted(cpu)
sched/core: Introduce the vcpu_is_preempted(cpu) interface
sched/wake_q: Rename WAKE_Q to DEFINE_WAKE_Q
locking/core: Provide common cpu_relax_yield() definition
locking/mutex: Don't mark mutex_trylock_recursive() as deprecated, temporarily
...
Pull SMP bootup updates from Ingo Molnar:
"Three changes to unify/standardize some of the bootup message printing
in kernel/smp.c between architectures"
* 'core-smp-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
kernel/smp: Tell the user we're bringing up secondary CPUs
kernel/smp: Make the SMP boot message common on all arches
kernel/smp: Define pr_fmt() for smp.c
Pull RCU updates from Ingo Molnar:
"The main RCU changes in this development cycle were:
- Miscellaneous fixes, including a change to call_rcu()'s rcu_head
alignment check.
- Security-motivated list consistency checks, which are disabled by
default behind DEBUG_LIST.
- Torture-test updates.
- Documentation updates, yet again just simple changes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
torture: Prevent jitter from delaying build-only runs
torture: Remove obsolete files from rcutorture .gitignore
rcu: Don't kick unless grace period or request
rcu: Make expedited grace periods recheck dyntick idle state
torture: Trace long read-side delays
rcu: RCU_TRACE enables event tracing as well as debugfs
rcu: Remove obsolete comment from __call_rcu()
rcu: Remove obsolete rcu_check_callbacks() header comment
rcu: Tighten up __call_rcu() rcu_head alignment check
Documentation/RCU: Fix minor typo
documentation: Present updated RCU guarantee
bug: Avoid Kconfig warning for BUG_ON_DATA_CORRUPTION
lib/Kconfig.debug: Fix typo in select statement
lkdtm: Add tests for struct list corruption
bug: Provide toggle for BUG on data corruption
list: Split list_del() debug checking into separate function
rculist: Consolidate DEBUG_LIST for list_add_rcu()
list: Split list_add() debug checking into separate function
find_idlest_group() only compares the runnable_load_avg when looking
for the least loaded group. But on fork intensive use case like
hackbench where tasks blocked quickly after the fork, this can lead to
selecting the same CPU instead of other CPUs, which have similar
runnable load but a lower load_avg.
When the runnable_load_avg of 2 CPUs are close, we now take into
account the amount of blocked load as a 2nd selection factor. There is
now 3 zones for the runnable_load of the rq:
- [0 .. (runnable_load - imbalance)]:
Select the new rq which has significantly less runnable_load
- [(runnable_load - imbalance) .. (runnable_load + imbalance)]:
The runnable loads are close so we use load_avg to chose
between the 2 rq
- [(runnable_load + imbalance) .. ULONG_MAX]:
Keep the current rq which has significantly less runnable_load
The scale factor that is currently used for comparing runnable_load,
doesn't work well with small value. As an example, the use of a
scaling factor fails as soon as this_runnable_load == 0 because we
always select local rq even if min_runnable_load is only 1, which
doesn't really make sense because they are just the same. So instead
of scaling factor, we use an absolute margin for runnable_load to
detect CPUs with similar runnable_load and we keep using scaling
factor for blocked load.
For use case like hackbench, this enable the scheduler to select
different CPUs during the fork sequence and to spread tasks across the
system.
Tests have been done on a Hikey board (ARM based octo cores) for
several kernel. The result below gives min, max, avg and stdev values
of 18 runs with each configuration.
The patches depend on the "no missing update_rq_clock()" work.
hackbench -P -g 1
ea86cb4b767dc603c902 v4.8 v4.8+patches
min 0.049 0.050 0.051 0,048
avg 0.057 0.057(0%) 0.057(0%) 0,055(+5%)
max 0.066 0.068 0.070 0,063
stdev +/-9% +/-9% +/-8% +/-9%
More performance numbers here:
https://lkml.kernel.org/r/20161203214707.GI20785@codeblueprint.co.uk
Tested-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: kernellwp@gmail.com
Cc: umgwanakikbuti@gmail.com
Cc: yuyang.du@intel.comc
Link: http://lkml.kernel.org/r/1481216215-24651-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
During fork, the utilization of a task is init once the rq has been
selected because the current utilization level of the rq is used to
set the utilization of the fork task. As the task's utilization is
still 0 at this step of the fork sequence, it doesn't make sense to
look for some spare capacity that can fit the task's utilization.
Furthermore, I can see perf regressions for the test:
hackbench -P -g 1
because the least loaded policy is always bypassed and tasks are not
spread during fork.
With this patch and the fix below, we are back to same performances as
for v4.8. The fix below is only a temporary one used for the test
until a smarter solution is found because we can't simply remove the
test which is useful for others benchmarks
| @@ -5708,13 +5708,6 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
|
| avg_cost = this_sd->avg_scan_cost;
|
| - /*
| - * Due to large variance we need a large fuzz factor; hackbench in
| - * particularly is sensitive here.
| - */
| - if ((avg_idle / 512) < avg_cost)
| - return -1;
| -
| time = local_clock();
|
| for_each_cpu_wrap(cpu, sched_domain_span(sd), target, wrap) {
Tested-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: kernellwp@gmail.com
Cc: umgwanakikbuti@gmail.com
Cc: yuyang.du@intel.comc
Link: http://lkml.kernel.org/r/1481216215-24651-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently both the wakeup and irqsoff traces do not handle set_graph_notrace
well. The ftrace infrastructure will ignore the return paths of all
functions leaving them hanging without an end:
# echo '*spin*' > set_graph_notrace
# cat trace
[...]
_raw_spin_lock() {
preempt_count_add() {
do_raw_spin_lock() {
update_rq_clock();
Where the '*spin*' functions should have looked like this:
_raw_spin_lock() {
preempt_count_add();
do_raw_spin_lock();
}
update_rq_clock();
Instead, have the wakeup and irqsoff tracers ignore the functions that are
set by the set_graph_notrace like the function_graph tracer does. Move
the logic in the function_graph tracer into a header to allow wakeup and
irqsoff tracers to use it as well.
Cc: Namhyung Kim <namhyung.kim@lge.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Both the wakeup and irqsoff tracers can use the function graph tracer when
the display-graph option is set. The problem is that they ignore the notrace
file, and record the entry of functions that would be ignored by the
function_graph tracer. This causes the trace->depth to be recorded into the
ring buffer. The set_graph_notrace uses a trick by adding a large negative
number to the trace->depth when a graph function is to be ignored.
On trace output, the graph function uses the depth to record a stack of
functions. But since the depth is negative, it accesses the array with a
negative number and causes an out of bounds access that can cause a kernel
oops or corrupt data.
Have the print functions handle cases where a tracer still records functions
even when they are in set_graph_notrace.
Also add warnings if the depth is below zero before accessing the array.
Note, the function graph logic will still prevent the return of these
functions from being recorded, which means that they will be left hanging
without a return. For example:
# echo '*spin*' > set_graph_notrace
# echo 1 > options/display-graph
# echo wakeup > current_tracer
# cat trace
[...]
_raw_spin_lock() {
preempt_count_add() {
do_raw_spin_lock() {
update_rq_clock();
Where it should look like:
_raw_spin_lock() {
preempt_count_add();
do_raw_spin_lock();
}
update_rq_clock();
Cc: stable@vger.kernel.org
Cc: Namhyung Kim <namhyung.kim@lge.com>
Fixes: 29ad23b004 ("ftrace: Add set_graph_notrace filter")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Instead of using get_user_pages_fast() and kmap_atomic() when writing
to the trace_marker file, just allocate enough space on the ring buffer
directly, and write into it via copy_from_user().
Writing into the trace_marker file use to allocate a temporary buffer
to perform the copy_from_user(), as we didn't want to write into the
ring buffer if the copy failed. But as a trace_marker write is suppose
to be extremely fast, and allocating memory causes other tracepoints to
trigger, Peter Zijlstra suggested using get_user_pages_fast() and
kmap_atomic() to keep the user space pages in memory and reading it
directly. But Henrik Austad had issues with this because it required taking
the mm->mmap_sem and causing long delays with the write.
Instead, just allocate the space in the ring buffer and use
copy_from_user() directly. If it faults, return -EFAULT and write
"<faulted>" into the ring buffer.
Link: http://lkml.kernel.org/r/20161208124018.72dd0f86@gandalf.local.home
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Henrik Austad <henrik@austad.us>
Cc: Peter Zijlstra <peterz@infradead.org>
Updates: d696b58ca2 "tracing: Do not allocate buffer for trace_marker"
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The trace event start up selftests fails when the trace benchmark is
enabled, because it is disabled during boot. It really only needs to be
disabled before scheduling is set up, as it creates a thread.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If one of the events within a system fails to enable when "1" is written
to the system "enable" file, it should return an error. Note, some events
may still be enabled, but the user should know that something did go wrong.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Trace events are enabled very early on boot up via the boot command line
parameter. The benchmark tool creates a new thread to perform the trace
event benchmarking. But at start up, it is called before scheduling is set
up and because it creates a new thread before the init thread is created,
this crashes the kernel.
Have the benchmark fail to register when started via the kernel command
line.
Also, since the registering of a tracepoint now can handle failure cases,
return -ENOMEM instead of warning if the thread cannot be created.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Some tracepoints have a registration function that gets enabled when the
tracepoint is enabled. There may be cases that the registraction function
must fail (for example, can't allocate enough memory). In this case, the
tracepoint should also fail to register, otherwise the user would not know
why the tracepoint is not working.
Cc: David Howells <dhowells@redhat.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The clocksource delta to nanoseconds conversion is using signed math, but
the delta is unsigned. This makes the conversion space smaller than
necessary and in case of a multiplication overflow the conversion can
become negative. The conversion is done with scaled math:
s64 nsec_delta = ((s64)clkdelta * clk->mult) >> clk->shift;
Shifting a signed integer right obvioulsy preserves the sign, which has
interesting consequences:
- Time jumps backwards
- __iter_div_u64_rem() which is used in one of the calling code pathes
will take forever to piecewise calculate the seconds/nanoseconds part.
This has been reported by several people with different scenarios:
David observed that when stopping a VM with a debugger:
"It was essentially the stopped by debugger case. I forget exactly why,
but the guest was being explicitly stopped from outside, it wasn't just
scheduling lag. I think it was something in the vicinity of 10 minutes
stopped."
When lifting the stop the machine went dead.
The stopped by debugger case is not really interesting, but nevertheless it
would be a good thing not to die completely.
But this was also observed on a live system by Liav:
"When the OS is too overloaded, delta will get a high enough value for the
msb of the sum delta * tkr->mult + tkr->xtime_nsec to be set, and so
after the shift the nsec variable will gain a value similar to
0xffffffffff000000."
Unfortunately this has been reintroduced recently with commit 6bd58f09e1
("time: Add cycles to nanoseconds translation"). It had been fixed a year
ago already in commit 35a4933a89 ("time: Avoid signed overflow in
timekeeping_get_ns()").
Though it's not surprising that the issue has been reintroduced because the
function itself and the whole call chain uses s64 for the result and the
propagation of it. The change in this recent commit is subtle:
s64 nsec;
- nsec = (d * m + n) >> s:
+ nsec = d * m + n;
+ nsec >>= s;
d being type of cycle_t adds another level of obfuscation.
This wouldn't have happened if the previous change to unsigned computation
would have made the 'nsec' variable u64 right away and a follow up patch
had cleaned up the whole call chain.
There have been patches submitted which basically did a revert of the above
patch leaving everything else unchanged as signed. Back to square one. This
spawned a admittedly pointless discussion about potential users which rely
on the unsigned behaviour until someone pointed out that it had been fixed
before. The changelogs of said patches added further confusion as they made
finally false claims about the consequences for eventual users which expect
signed results.
Despite delta being cycle_t, aka. u64, it's very well possible to hand in
a signed negative value and the signed computation will happily return the
correct result. But nobody actually sat down and analyzed the code which
was added as user after the propably unintended signed conversion.
Though in sensitive code like this it's better to analyze it proper and
make sure that nothing relies on this than hunting the subtle wreckage half
a year later. After analyzing all call chains it stands that no caller can
hand in a negative value (which actually would work due to the s64 cast)
and rely on the signed math to do the right thing.
Change the conversion function to unsigned math. The conversion of all call
chains is done in a follow up patch.
This solves the starvation issue, which was caused by the negative result,
but it does not solve the underlying problem. It merily procrastinates
it. When the timekeeper update is deferred long enough that the unsigned
multiplication overflows, then time going backwards is observable again.
It does neither solve the issue of clocksources with a small counter width
which will wrap around possibly several times and cause random time stamps
to be generated. But those are usually not found on systems used for
virtualization, so this is likely a non issue.
I took the liberty to claim authorship for this simply because
analyzing all callsites and writing the changelog took substantially
more time than just making the simple s/s64/u64/ change and ignore the
rest.
Fixes: 6bd58f09e1 ("time: Add cycles to nanoseconds translation")
Reported-by: David Gibson <david@gibson.dropbear.id.au>
Reported-by: Liav Rehana <liavr@mellanox.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Parit Bhargava <prarit@redhat.com>
Cc: Laurent Vivier <lvivier@redhat.com>
Cc: "Christopher S. Hall" <christopher.s.hall@intel.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20161208204228.688545601@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch allows XDP prog to extend/remove the packet
data at the head (like adding or removing header). It is
done by adding a new XDP helper bpf_xdp_adjust_head().
It also renames bpf_helper_changes_skb_data() to
bpf_helper_changes_pkt_data() to better reflect
that XDP prog does not work on skb.
This patch adds one "xdp_adjust_head" bit to bpf_prog for the
XDP-capable driver to check if the XDP prog requires
bpf_xdp_adjust_head() support. The driver can then decide
to error out during XDP_SETUP_PROG.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commmits 57a09bf0a4 ("bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registers")
and 484611357c ("bpf: allow access into map value arrays") by themselves
are correct, but in combination they make state equivalence ignore 'id' field
of the register state which can lead to accepting invalid program.
Fixes: 57a09bf0a4 ("bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registers")
Fixes: 484611357c ("bpf: allow access into map value arrays")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
kthread_create_on_cpu() sets KTHREAD_IS_PER_CPU and kthread->cpu, this
only makes sense if this kthread can be parked/unparked by cpuhp code.
kthread workers never call kthread_parkme() so this has no effect.
Change __kthread_create_worker() to simply call kthread_bind(task, cpu).
The very fact that kthread_create_on_cpu() doesn't accept a generic fmt
shows that it should not be used outside of smpboot.c.
Now, the only reason we can not unexport this helper and move it into
smpboot.c is that it sets kthread->cpu and struct kthread is not exported.
And the only reason we can not kill kthread->cpu is that kthread_unpark()
is used by drivers/gpu/drm/amd/scheduler/gpu_scheduler.c and thus we can
not turn _unpark into kthread_unpark(struct smp_hotplug_thread *, cpu).
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Chunming Zhou <David1.Zhou@amd.com>
Cc: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20161129175110.GA5342@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now that to_kthread() is always validm change kthread_park() and
kthread_unpark() to use it and kill to_live_kthread().
The conversion of kthread_unpark() is trivial. If KTHREAD_IS_PARKED is set
then the task has called complete(&self->parked) and there the function
cannot race against a concurrent kthread_stop() and exit.
kthread_park() is more tricky, because its semantics are not well
defined. It returns -ENOSYS if the thread exited but this can never happen
and as Roman pointed out kthread_park() can obviously block forever if it
would race with the exiting kthread.
The usage of kthread_park() in cpuhp code (cpu.c, smpboot.c, stop_machine.c)
is fine. It can never see an exiting/exited kthread, smpboot_destroy_threads()
clears *ht->store, smpboot_park_thread() checks it is not NULL under the same
smpboot_threads_lock. cpuhp_threads and cpu_stop_threads never exit, so other
callers are fine too.
But it has two more users:
- watchdog_park_threads():
The code is actually correct, get_online_cpus() ensures that
kthread_park() can't race with itself (note that kthread_park() can't
handle this race correctly), but it should not use kthread_park()
directly.
- drivers/gpu/drm/amd/scheduler/gpu_scheduler.c should not use
kthread_park() either.
kthread_park() must not be called after amd_sched_fini() which does
kthread_stop(), otherwise even to_live_kthread() is not safe because
task_struct can be already freed and sched->thread can point to nowhere.
The usage of kthread_park/unpark should either be restricted to core code
which is properly protected against the exit race or made more robust so it
is safe to use it in drivers.
To catch eventual exit issues, add a WARN_ON(PF_EXITING) for now.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chunming Zhou <David1.Zhou@amd.com>
Cc: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20161129175107.GA5339@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
kthread_stop() had to use to_live_kthread() simply because it was not
possible to access kthread->exited after the exiting task clears
task_struct->vfork_done. Now that to_kthread() is always valid,
wake_up_process() + wait_for_completion() can be done
ununconditionally. It's not an issue anymore if the task has already issued
complete_vfork_done() or died.
The exiting task can get the spurious wakeup after mm_release() but this is
possible without this change too and is fine; do_task_dead() ensures that
this can't make any harm.
As a further enhancement this could be converted to task_work_add() later,
so ->vfork_done can be avoided completely.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chunming Zhou <David1.Zhou@amd.com>
Cc: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20161129175103.GA5336@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Yu Zhao has noticed that __unregister_cpu_notifier only unregisters its
notifiers when HOTPLUG_CPU=y while the registration might succeed even
when HOTPLUG_CPU=n if MODULE is enabled. This means that e.g. zswap
might keep a stale notifier on the list on the manual clean up during
the pool tear down and thus corrupt the list. Resulting in the following
[ 144.964346] BUG: unable to handle kernel paging request at ffff880658a2be78
[ 144.971337] IP: [<ffffffffa290b00b>] raw_notifier_chain_register+0x1b/0x40
<snipped>
[ 145.122628] Call Trace:
[ 145.125086] [<ffffffffa28e5cf8>] __register_cpu_notifier+0x18/0x20
[ 145.131350] [<ffffffffa2a5dd73>] zswap_pool_create+0x273/0x400
[ 145.137268] [<ffffffffa2a5e0fc>] __zswap_param_set+0x1fc/0x300
[ 145.143188] [<ffffffffa2944c1d>] ? trace_hardirqs_on+0xd/0x10
[ 145.149018] [<ffffffffa2908798>] ? kernel_param_lock+0x28/0x30
[ 145.154940] [<ffffffffa2a3e8cf>] ? __might_fault+0x4f/0xa0
[ 145.160511] [<ffffffffa2a5e237>] zswap_compressor_param_set+0x17/0x20
[ 145.167035] [<ffffffffa2908d3c>] param_attr_store+0x5c/0xb0
[ 145.172694] [<ffffffffa290848d>] module_attr_store+0x1d/0x30
[ 145.178443] [<ffffffffa2b2b41f>] sysfs_kf_write+0x4f/0x70
[ 145.183925] [<ffffffffa2b2a5b9>] kernfs_fop_write+0x149/0x180
[ 145.189761] [<ffffffffa2a99248>] __vfs_write+0x18/0x40
[ 145.194982] [<ffffffffa2a9a412>] vfs_write+0xb2/0x1a0
[ 145.200122] [<ffffffffa2a9a732>] SyS_write+0x52/0xa0
[ 145.205177] [<ffffffffa2ff4d97>] entry_SYSCALL_64_fastpath+0x12/0x17
This can be even triggered manually by changing
/sys/module/zswap/parameters/compressor multiple times.
Fix this issue by making unregister APIs symmetric to the register so
there are no surprises.
Fixes: 47e627bc8c ("[PATCH] hotplug: Allow modules to use the cpu hotplug notifiers even if !CONFIG_HOTPLUG_CPU")
Reported-and-tested-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Link: http://lkml.kernel.org/r/20161207135438.4310-1-mhocko@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull perf fixes from Ingo Molnar:
"A bogus warning fix, a counter width handling fix affecting certain
machines, plus a oneliner hw-enablement patch for Knights Mill CPUs"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Remove invalid warning from list_update_cgroup_even()t
perf/x86: Fix full width counter, counter overflow
perf/x86/intel: Enable C-state residency events for Knights Mill
Pull locking fixes from Ingo Molnar:
"Two rtmutex race fixes (which miraculously never triggered, that we
know of), plus two lockdep printk formatting regression fixes"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
lockdep: Fix report formatting
locking/rtmutex: Use READ_ONCE() in rt_mutex_owner()
locking/rtmutex: Prevent dequeue vs. unlock race
locking/selftest: Fix output since KERN_CONT changes
General assumption is that single program can hold up to BPF_MAXINSNS,
that is, 4096 number of instructions. It is the case with cBPF and
that limit was carried over to eBPF. When recently testing digest, I
noticed that it's actually not possible to feed 4096 instructions
via bpf(2).
The check for > BPF_MAXINSNS was added back then to bpf_check() in
cbd3570086 ("bpf: verifier (add ability to receive verification log)").
However, 09756af468 ("bpf: expand BPF syscall with program load/unload")
added yet another check that comes before that into bpf_prog_load(),
but this time bails out already in case of >= BPF_MAXINSNS.
Fix it up and perform the check early in bpf_prog_load(), so we can drop
the second one in bpf_check(). It makes sense, because also a 0 insn
program is useless and we don't want to waste any resources doing work
up to bpf_check() point. The existing bpf(2) man page documents E2BIG
as the official error for such cases, so just stick with it as well.
Fixes: 09756af468 ("bpf: expand BPF syscall with program load/unload")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The CPSW CPTS driver is capable of doing timestamping on tx/rx packets and
requires to know mult and shift factors for timestamp conversion from raw
value to nanoseconds (ptp clock). Now these mult and shift factors are
calculated manually and provided through DT, which makes very hard to
support of a lot number of platforms, especially if CPTS refclk is not the
same for some kind of boards and depends on efuse settings (Keystone 2
platforms). Hence, export clocks_calc_mult_shift() to allow drivers like
CPSW CPTS (and other ptp drivesr) to benefit from automaitc calculation of
mult and shift factors.
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Before commit b32614c034 ("tracing/rb: Convert to hotplug state machine")
the allocated cpumask was initialized to the mask of online or possible
CPUs. After the CPU hotplug changes the buffer initialization moved to
trace_rb_cpu_prepare() but the cpumask is allocated with alloc_cpumask()
and therefor has random content. As a consequence the cpu buffers are not
initialized and a later access dereferences a NULL pointer.
Use zalloc_cpumask() instead so trace_rb_cpu_prepare() initializes the
buffers properly.
Fixes: b32614c034 ("tracing/rb: Convert to hotplug state machine")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20161207133133.hzkcqfllxcdi3joz@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since commit:
4bcc595ccd ("printk: reinstate KERN_CONT for printing continuation lines")
printk() requires KERN_CONT to continue log messages. Lots of printk()
in lockdep.c and print_ip_sym() don't have it. As the result lockdep
reports are completely messed up.
Add missing KERN_CONT and inline print_ip_sym() where necessary.
Example of a messed up report:
0-rc5+ #41 Not tainted
-------------------------------------------------------
syz-executor0/5036 is trying to acquire lock:
(
rtnl_mutex
){+.+.+.}
, at:
[<ffffffff86b3d6ac>] rtnl_lock+0x1c/0x20
but task is already holding lock:
(
&net->packet.sklist_lock
){+.+...}
, at:
[<ffffffff873541a6>] packet_diag_dump+0x1a6/0x1920
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3
(
&net->packet.sklist_lock
+.+...}
...
Without this patch all scripts that parse kernel bug reports are broken.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andreyknvl@google.com
Cc: aryabinin@virtuozzo.com
Cc: joe@perches.com
Cc: syzkaller@googlegroups.com
Link: http://lkml.kernel.org/r/1480343083-48731-1-git-send-email-dvyukov@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
