In apply_slack(), find_last_bit() is applied to a bitmask consisting
of precisely BITS_PER_LONG bits. Since mask is non-zero, we might as
well eliminate the function call and use __fls() directly. On x86_64,
this shaves 23 bytes of the only caller, mod_timer().
This also gets rid of Coverity CID 1192106, but that is a false
positive: Coverity is not aware that mask != 0 implies that
find_last_bit will not return BITS_PER_LONG.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1443771931-6284-1-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull scheduler fix from Thomas Gleixner:
"Fix a long standing state race in finish_task_switch()"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Fix TASK_DEAD race in finish_task_switch()
A recent cleanup removed the 'irq' parameter from many functions, but
left the documentation for this in place for at least one function.
This removes it.
Fixes: bd0b9ac405 ("genirq: Remove irq argument from irq flow handlers")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: kbuild-all@01.org
Cc: Austin Schuh <austin@peloton-tech.com>
Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/5400000.cD19rmgWjV@wuerfel
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
A cleanup of the omap gpio driver introduced a use of the
handle_bad_irq() function in a device driver that can be
a loadable module.
This broke the ARM allmodconfig build:
ERROR: "handle_bad_irq" [drivers/gpio/gpio-omap.ko] undefined!
This patch exports the handle_bad_irq symbol in order to
allow the use in modules.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Austin Schuh <austin@peloton-tech.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/5847725.4IBopItaOr@wuerfel
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
So the problem this patch is trying to address is as follows:
CPU0 CPU1
context_switch(A, B)
ttwu(A)
LOCK A->pi_lock
A->on_cpu == 0
finish_task_switch(A)
prev_state = A->state <-.
WMB |
A->on_cpu = 0; |
UNLOCK rq0->lock |
| context_switch(C, A)
`-- A->state = TASK_DEAD
prev_state == TASK_DEAD
put_task_struct(A)
context_switch(A, C)
finish_task_switch(A)
A->state == TASK_DEAD
put_task_struct(A)
The argument being that the WMB will allow the load of A->state on CPU0
to cross over and observe CPU1's store of A->state, which will then
result in a double-drop and use-after-free.
Now the comment states (and this was true once upon a long time ago)
that we need to observe A->state while holding rq->lock because that
will order us against the wakeup; however the wakeup will not in fact
acquire (that) rq->lock; it takes A->pi_lock these days.
We can obviously fix this by upgrading the WMB to an MB, but that is
expensive, so we'd rather avoid that.
The alternative this patch takes is: smp_store_release(&A->on_cpu, 0),
which avoids the MB on some archs, but not important ones like ARM.
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org> # v3.1+
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: manfred@colorfullife.com
Cc: will.deacon@arm.com
Fixes: e4a52bcb9a ("sched: Remove rq->lock from the first half of ttwu()")
Link: http://lkml.kernel.org/r/20150929124509.GG3816@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull irq fixes from Thomas Gleixner:
"This update contains:
- Fix for a long standing race affecting /proc/irq/NNN
- One line fix for ARM GICV3-ITS counting the wrong data
- Warning silencing in ARM GICV3-ITS. Another GCC trying to be
overly clever issue"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/gic-v3-its: Count additional LPIs for the aliased devices
irqchip/gic-v3-its: Silence warning when its_lpi_alloc_chunks gets inlined
genirq: Fix race in register_irq_proc()
This patch fixes one cases where abs() was being used with 64-bit
nanosecond values, where the result may be capped at 32-bits.
This potentially could cause watchdog false negatives on 32-bit
systems, so this patch addresses the issue by using abs64().
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1442279124-7309-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Per-IRQ directories in procfs are created only when a handler is first
added to the irqdesc, not when the irqdesc is created. In the case of
a shared IRQ, multiple tasks can race to create a directory. This
race condition seems to have been present forever, but is easier to
hit with async probing.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Link: http://lkml.kernel.org/r/1443266636.2004.2.camel@decadent.org.uk
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Pull RCU fixes from Ingo Molnar:
"Two RCU fixes:
- work around bug with recent GCC versions.
- fix false positive lockdep splat"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex
rcu: Change _wait_rcu_gp() to work around GCC bug 67055
Pull RCU fixes from Paul E. McKenney, for two regressions
introduced in this merge window:
- Fix bug with recent GCCs.
- Fix false positive lockdep splat.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull perf fixes from Thomas Gleixner:
"Another pile of fixes for perf:
- Plug overflows and races in the core code
- Sanitize the flow of the perf syscall so we error out before
handling the more complex and hard to undo setups
- Improve and fix Broadwell and Skylake hardware support
- Revert a fix which broke what it tried to fix in perf tools
- A couple of smaller fixes in various places of perf tools"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf tools: Fix copying of /proc/kcore
perf intel-pt: Remove no_force_psb from documentation
perf probe: Use existing routine to look for a kernel module by dso->short_name
perf/x86: Change test_aperfmperf() and test_intel() to static
tools lib traceevent: Fix string handling in heterogeneous arch environments
perf record: Avoid infinite loop at buildid processing with no samples
perf: Fix races in computing the header sizes
perf: Fix u16 overflows
perf: Restructure perf syscall point of no return
perf/x86/intel: Fix Skylake FRONTEND MSR extrareg mask
perf/x86/intel/pebs: Add PEBS frontend profiling for Skylake
perf/x86/intel: Make the CYCLE_ACTIVITY.* constraint on Broadwell more specific
perf tools: Bool functions shouldn't return -1
tools build: Add test for presence of __get_cpuid() gcc builtin
tools build: Add test for presence of numa_num_possible_cpus() in libnuma
Revert "perf symbols: Fix mismatched declarations for elf_getphdrnum"
perf stat: Fix per-pkg event reporting bug
Pull scheduler fix from Thomas Gleixner:
"A single bug fix for the scheduler to prevent dequeueing of the idle
task when setting the cpus allowed mask"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Fix crash trying to dequeue/enqueue the idle thread
Pull locking fix from Thomas Gleixner:
"A single bugfix for lockdep to preserve the pinning counter when
rebuilding the lock stack"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/lockdep: Fix hlock->pin_count reset on lock stack rebuilds
Various people reported hitting the "unpinning an unpinned lock"
warning. As it turns out there are 2 places where we take a lock out
of the middle of a stack, and in those cases it would fail to preserve
the pin_count when rebuilding the lock stack.
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Reported-by: Tim Spriggs <tspriggs@apple.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davej@codemonkey.org.uk
Link: http://lkml.kernel.org/r/20150916141040.GA11639@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This reverts commit 51360155ec and adapts
fs/userfaultfd.c to use the old version of that function.
It didn't look robust to call __wake_up_common with "nr == 1" when we
absolutely require wakeall semantics, but we've full control of what we
insert in the two waitqueue heads of the blocked userfaults. No
exclusive waitqueue risks to be inserted into those two waitqueue heads
so we can as well stick to "nr == 1" of the old code and we can rely
purely on the fact no waitqueue inserted in one of the two waitqueue
heads we must enforce as wakeall, has wait->flags WQ_FLAG_EXCLUSIVE set.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
timer_stats_account_timer() reads timer->start_site, then checks it
for NULL and then re-reads it again, while
timer_stats_timer_clear_start_info() can concurrently reset
timer->start_site to NULL. This should not lead to crashes, but can
double number of entries in timer stats as start_site is used during
comparison, the doubled entries will have unuseful NULL start_site.
Read timer->start_site only once in timer_stats_account_timer().
The data race was found with KernelThreadSanitizer (KTSAN).
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: andreyknvl@google.com
Cc: glider@google.com
Cc: kcc@google.com
Cc: ktsan@googlegroups.com
Cc: john.stultz@linaro.org
Link: http://lkml.kernel.org/r/1442584463-69553-1-git-send-email-dvyukov@google.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tianhong Ding <dingtianhong@huawei.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Xinwei Hu <huxinwei@huawei.com>
Cc: Xunlei Pang <pang.xunlei@linaro.org>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1440484973-13892-1-git-send-email-thunder.leizhen@huawei.com
[ Fixed yet another typo in one of the sentences fixed. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull cgroup fixes from Tejun Heo:
"The threadgroup locking changes which went in during 4.2 devel cycle
added write locking of a percpu_rwsem in cgroup task migration path;
unfortunately, that involved expedited rcu syncing which turned out to
be too slow and heavy for certain workloads. The patchset which is
dependent on this one didn't get committed during that devel cycle, so
these two patches can be reverted safely.
Oleg reworked percpu_rwsem for 4.4 so that the writer path is a lot
lighter. The reported issue goes away with Oleg's reworked
percpu_rwsem and I'll reapply these patches on the for-4.4 branch so
that they can land together with Oleg's changes"
* 'for-4.3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
Revert "sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem"
Revert "cgroup: simplify threadgroup locking"
In kernels built with CONFIG_PREEMPT=y, synchronize_rcu_expedited()
invokes synchronize_sched_expedited() while holding RCU-preempt's
root rcu_node structure's ->exp_funnel_mutex, which is acquired after
the rcu_data structure's ->exp_funnel_mutex. The first thing that
synchronize_sched_expedited() will do is acquire RCU-sched's rcu_data
structure's ->exp_funnel_mutex. There is no danger of an actual deadlock
because the locking order is always from RCU-preempt's expedited mutexes
to those of RCU-sched. Unfortunately, lockdep considers both rcu_data
structures' ->exp_funnel_mutex to be in the same lock class and therefore
reports a deadlock cycle.
This commit silences this false positive by placing RCU-sched's rcu_data
structures' ->exp_funnel_mutex locks into their own lock class.
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.22 (GNU/Linux)
iQEcBAABAgAGBQJV+/ucAAoJEL/70l94x66DV8YH/1KDym/1GJ+/Br/YkHZnM53l
3Q0PwSLu9cNcIL9lUuDLwGTaVj+y8ud1Hjr/uzvKwivktmUYVZhkdtnZmnanvGOM
qKB9K3nFXCPx8uqy8Dn7fOwEKcg9FmDOTTkWy13HDnXO+V4crSVVt+rPw+6FUMld
NV5tYdw9Lu7y3XrveDebPWaPtyDL7OAagzmeK47eMffxG7X9Hf1H2aT7HueRi7x/
SkLIe3gmiOWmHVJDPE9TOmFYIj19gywDFysKes1gdVJLVUIXiELMT7SrvAYnToVB
zISIEj7Zx4SINPxpf2dUn8REm7NsmJY+PffLIl/Nv+ozGggFQGFH0SMZ08p0bxw=
=tfmn
-----END PGP SIGNATURE-----
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM fixes from Paolo Bonzini:
"Mostly stable material, a lot of ARM fixes"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (22 commits)
sched: access local runqueue directly in single_task_running
arm/arm64: KVM: Remove 'config KVM_ARM_MAX_VCPUS'
arm64: KVM: Remove all traces of the ThumbEE registers
arm: KVM: Disable virtual timer even if the guest is not using it
arm64: KVM: Disable virtual timer even if the guest is not using it
arm/arm64: KVM: vgic: Check for !irqchip_in_kernel() when mapping resources
KVM: s390: Replace incorrect atomic_or with atomic_andnot
arm: KVM: Fix incorrect device to IPA mapping
arm64: KVM: Fix user access for debug registers
KVM: vmx: fix VPID is 0000H in non-root operation
KVM: add halt_attempted_poll to VCPU stats
kvm: fix zero length mmio searching
kvm: fix double free for fast mmio eventfd
kvm: factor out core eventfd assign/deassign logic
kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd
KVM: make the declaration of functions within 80 characters
KVM: arm64: add workaround for Cortex-A57 erratum #852523
KVM: fix polling for guest halt continued even if disable it
arm/arm64: KVM: Fix PSCI affinity info return value for non valid cores
arm64: KVM: set {v,}TCR_EL2 RES1 bits
...
Pull irq updates from Thomas Gleixner:
"This is a rather large update post rc1 due to the final steps of
cleanups and API changes which had to wait for the preparatory patches
to hit your tree.
- Regression fixes for ARM GIC irqchips
- Regression fixes and lockdep anotations for renesas irq chips
- The leftovers of the cleanup and preparatory patches which have
been ignored by maintainers
- Final conversions of the newly merged users of obsolete APIs
- Final removal of obsolete APIs
- Final removal of ARM artifacts which had been introduced during the
conversion of ARM to the generic interrupt code.
- Final split of the irq_data into chip specific and common data to
reflect the needs of hierarchical irq domains.
- Treewide removal of the first argument of interrupt flow handlers,
i.e. the irq number, which is not used by the majority of handlers
and simple to retrieve from the other argument the irq descriptor.
- A few comment updates and build warning fixes"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
arm64: Remove ununsed set_irq_flags
ARM: Remove ununsed set_irq_flags
sh: Kill off set_irq_flags usage
irqchip: Kill off set_irq_flags usage
gpu/drm: Kill off set_irq_flags usage
genirq: Remove irq argument from irq flow handlers
genirq: Move field 'msi_desc' from irq_data into irq_common_data
genirq: Move field 'affinity' from irq_data into irq_common_data
genirq: Move field 'handler_data' from irq_data into irq_common_data
genirq: Move field 'node' from irq_data into irq_common_data
irqchip/gic-v3: Use IRQD_FORWARDED_TO_VCPU flag
irqchip/gic: Use IRQD_FORWARDED_TO_VCPU flag
genirq: Provide IRQD_FORWARDED_TO_VCPU status flag
genirq: Simplify irq_data_to_desc()
genirq: Remove __irq_set_handler_locked()
pinctrl/pistachio: Use irq_set_handler_locked
gpio: vf610: Use irq_set_handler_locked
powerpc/mpc8xx: Use irq_set_handler_locked()
powerpc/ipic: Use irq_set_handler_locked()
powerpc/cpm2: Use irq_set_handler_locked()
...
Commit 2ee507c472 ("sched: Add function single_task_running to let a task
check if it is the only task running on a cpu") referenced the current
runqueue with the smp_processor_id. When CONFIG_DEBUG_PREEMPT is enabled,
that is only allowed if preemption is disabled or the currrent task is
bound to the local cpu (e.g. kernel worker).
With commit f781951299 ("kvm: add halt_poll_ns module parameter") KVM
calls single_task_running. If CONFIG_DEBUG_PREEMPT is enabled that
generates a lot of kernel messages.
To avoid adding preemption in that cases, as it would limit the usefulness,
we change single_task_running to access directly the cpu local runqueue.
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Fixes: 2ee507c472
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There are two races with the current code:
- Another event can join the group and compute a larger header_size
concurrently, if the smaller store wins we'll have an incorrect
header_size set.
- We compute the header_size after the event becomes active,
therefore its possible to use the size before its computed.
Remedy the first by moving the computation inside the ctx::mutex lock,
and the second by placing it _before_ perf_install_in_context().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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>
Vince reported that its possible to overflow the various size fields
and get weird stuff if you stick too many events in a group.
Put a lid on this by requiring the fixed record size not exceed 16k.
This is still a fair amount of events (silly amount really) and leaves
plenty room for callchains and stack dwarves while also avoiding
overflowing the u16 variables.
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
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: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The exclusive_event_installable() stuff only works because its
exclusive with the grouping bits.
Rework the code such that there is a sane place to error out before we
go do things we cannot undo.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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>
Sasha reports that his virtual machine tries to schedule the idle
thread since commit 6c37067e27 ("sched: Change the
sched_class::set_cpus_allowed() calling context").
Hit trace shows this happening from idle_thread_get()->init_idle(),
which is the _second_ init_idle() invocation on that task_struct, the
first being done through idle_init()->fork_idle(). (this code is
insane...)
Because we call init_idle() twice in a row, its ->sched_class ==
&idle_sched_class and ->on_rq = TASK_ON_RQ_QUEUED. This means
do_set_cpus_allowed() think we're queued and will call dequeue_task(),
which is implemented with BUG() for the idle class, seeing how
dequeueing the idle task is a daft thing.
Aside of the whole insanity of calling init_idle() _twice_, change the
code to call set_cpus_allowed_common() instead as this is 'obviously'
before the idle task gets ran etc..
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.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>
Fixes: 6c37067e27 ("sched: Change the sched_class::set_cpus_allowed() calling context")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull timer fixes from Ingo Molnar:
"A fix for an abs()/abs64() bug that caused too slow NTP convergence on
32-bit kernels, plus a removal of an obsolete clockevents driver
facility after all users got converted during the merge window"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clockevents: Remove unused set_mode() callback
time: Fix timekeeping_freqadjust()'s incorrect use of abs() instead of abs64()
Pull scheduler fixes from Ingo Molnar:
"A migrate_tasks() locking fix, and a late-coming nohz change plus a
nohz debug check"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: 'Annotate' migrate_tasks()
nohz: Assert existing housekeepers when nohz full enabled
nohz: Affine unpinned timers to housekeepers
Pull locking fixes from Ingo Molnar:
"Spinlock performance regression fix, plus documentation fixes"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/static_keys: Fix up the static keys documentation
locking/qspinlock/x86: Only emit the test-and-set fallback when building guest support
locking/qspinlock/x86: Fix performance regression under unaccelerated VMs
locking/static_keys: Fix a silly typo
This reverts commit d59cfc09c3.
d59cfc09c3 ("sched, cgroup: replace signal_struct->group_rwsem with
a global percpu_rwsem") and b5ba75b5fc ("cgroup: simplify
threadgroup locking") changed how cgroup synchronizes against task
fork and exits so that it uses global percpu_rwsem instead of
per-process rwsem; unfortunately, the write [un]lock paths of
percpu_rwsem always involve synchronize_rcu_expedited() which turned
out to be too expensive.
Improvements for percpu_rwsem are scheduled to be merged in the coming
v4.4-rc1 merge window which alleviates this issue. For now, revert
the two commits to restore per-process rwsem. They will be re-applied
for the v4.4-rc1 merge window.
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/g/55F8097A.7000206@de.ibm.com
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org # v4.2+
This reverts commit b5ba75b5fc.
d59cfc09c3 ("sched, cgroup: replace signal_struct->group_rwsem with
a global percpu_rwsem") and b5ba75b5fc ("cgroup: simplify
threadgroup locking") changed how cgroup synchronizes against task
fork and exits so that it uses global percpu_rwsem instead of
per-process rwsem; unfortunately, the write [un]lock paths of
percpu_rwsem always involve synchronize_rcu_expedited() which turned
out to be too expensive.
Improvements for percpu_rwsem are scheduled to be merged in the coming
v4.4-rc1 merge window which alleviates this issue. For now, revert
the two commits to restore per-process rwsem. They will be re-applied
for the v4.4-rc1 merge window.
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/g/55F8097A.7000206@de.ibm.com
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org # v4.2+
Most interrupt flow handlers do not use the irq argument. Those few
which use it can retrieve the irq number from the irq descriptor.
Remove the argument.
Search and replace was done with coccinelle and some extra helper
scripts around it. Thanks to Julia for her help!
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
MSI descriptors are per-irq instead of per irqchip, so move it into
struct irq_common_data.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/1433145945-789-35-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Irq affinity mask is per-irq instead of per irqchip, so move it into
struct irq_common_data.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: http://lkml.kernel.org/r/1433303281-27688-1-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Handler data (handler_data) is per-irq instead of per irqchip, so move
it into struct irq_common_data.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/1433145945-789-13-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
NUMA node information is per-irq instead of per-irqchip, so move it into
struct irq_common_data. Also use CONFIG_NUMA to guard irq_common_data.node.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: http://lkml.kernel.org/r/1433145945-789-8-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The internal clocksteering done for fine-grained error
correction uses a logarithmic approximation, so any time
adjtimex() adjusts the clock steering, timekeeping_freqadjust()
quickly approximates the correct clock frequency over a series
of ticks.
Unfortunately, the logic in timekeeping_freqadjust(), introduced
in commit:
dc491596f6 ("timekeeping: Rework frequency adjustments to work better w/ nohz")
used the abs() function with a s64 error value to calculate the
size of the approximated adjustment to be made.
Per include/linux/kernel.h:
"abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()".
Thus on 32-bit platforms, this resulted in the clocksteering to
take a quite dampended random walk trying to converge on the
proper frequency, which caused the adjustments to be made much
slower then intended (most easily observed when large
adjustments are made).
This patch fixes the issue by using abs64() instead.
Reported-by: Nuno Gonçalves <nunojpg@gmail.com>
Tested-by: Nuno Goncalves <nunojpg@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: <stable@vger.kernel.org> # v3.17+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1441840051-20244-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge fourth patch-bomb from Andrew Morton:
- sys_membarier syscall
- seq_file interface changes
- a few misc fixups
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
revert "ocfs2/dlm: use list_for_each_entry instead of list_for_each"
mm/early_ioremap: add explicit #include of asm/early_ioremap.h
fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void
selftests: enhance membarrier syscall test
selftests: add membarrier syscall test
sys_membarrier(): system-wide memory barrier (generic, x86)
MODSIGN: fix a compilation warning in extract-cert
- Build fix for the new Mediatek MT8173 cpufreq driver (Guenter Roeck).
- Generic power domains framework fixes (power on error code
path, subdomain removal) and cleanup of a deprecated API user
(Geert Uytterhoeven, Jon Hunter, Ulf Hansson).
- cpufreq-dt driver fixes including two fixes for bugs related to
the new Operating Performance Points Device Tree bindings
introduced recently (Viresh Kumar).
- Suspend frequency support for the cpufreq-dt driver
(Bartlomiej Zolnierkiewicz, Viresh Kumar).
- cpufreq core cleanups (Viresh Kumar).
- intel_pstate driver fixes (Chen Yu, Kristen Carlson Accardi).
- Additional sanity check in the cpuidle core (Xunlei Pang).
- Fix for a comment related to CPU power management (Lina Iyer).
/
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.22 (GNU/Linux)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=C7+4
-----END PGP SIGNATURE-----
Merge tag 'pm+acpi-4.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management and ACPI updates from Rafael Wysocki:
"These are mostly fixes and cleanups on top of the previous PM+ACPI
pull request (cpufreq core and drivers, cpuidle, generic power domains
framework). Some of them didn't make to that pull request and some
fix issues introduced by it.
The only really new thing is the support for suspend frequency in the
cpufreq-dt driver, but it is needed to fix an issue with Exynos
platforms.
Specifics:
- build fix for the new Mediatek MT8173 cpufreq driver (Guenter
Roeck).
- generic power domains framework fixes (power on error code path,
subdomain removal) and cleanup of a deprecated API user (Geert
Uytterhoeven, Jon Hunter, Ulf Hansson).
- cpufreq-dt driver fixes including two fixes for bugs related to the
new Operating Performance Points Device Tree bindings introduced
recently (Viresh Kumar).
- suspend frequency support for the cpufreq-dt driver (Bartlomiej
Zolnierkiewicz, Viresh Kumar).
- cpufreq core cleanups (Viresh Kumar).
- intel_pstate driver fixes (Chen Yu, Kristen Carlson Accardi).
- additional sanity check in the cpuidle core (Xunlei Pang).
- fix for a comment related to CPU power management (Lina Iyer)"
* tag 'pm+acpi-4.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
intel_pstate: fix PCT_TO_HWP macro
intel_pstate: Fix user input of min/max to legal policy region
PM / OPP: Return suspend_opp only if it is enabled
cpufreq-dt: add suspend frequency support
cpufreq: allow cpufreq_generic_suspend() to work without suspend frequency
PM / OPP: add dev_pm_opp_get_suspend_opp() helper
staging: board: Migrate away from __pm_genpd_name_add_device()
cpufreq: Use __func__ to print function's name
cpufreq: staticize cpufreq_cpu_get_raw()
PM / Domains: Ensure subdomain is not in use before removing
cpufreq: Add ARM_MT8173_CPUFREQ dependency on THERMAL
cpuidle/coupled: Add sanity check for safe_state_index
PM / Domains: Try power off masters in error path of __pm_genpd_poweron()
cpufreq: dt: Tolerance applies on both sides of target voltage
cpufreq: dt: Print error on failing to mark OPPs as shared
cpufreq: dt: Check OPP count before marking them shared
kernel/cpu_pm: fix cpu_cluster_pm_exit comment
Here is an implementation of a new system call, sys_membarrier(), which
executes a memory barrier on all threads running on the system. It is
implemented by calling synchronize_sched(). It can be used to
distribute the cost of user-space memory barriers asymmetrically by
transforming pairs of memory barriers into pairs consisting of
sys_membarrier() and a compiler barrier. For synchronization primitives
that distinguish between read-side and write-side (e.g. userspace RCU
[1], rwlocks), the read-side can be accelerated significantly by moving
the bulk of the memory barrier overhead to the write-side.
The existing applications of which I am aware that would be improved by
this system call are as follows:
* Through Userspace RCU library (http://urcu.so)
- DNS server (Knot DNS) https://www.knot-dns.cz/
- Network sniffer (http://netsniff-ng.org/)
- Distributed object storage (https://sheepdog.github.io/sheepdog/)
- User-space tracing (http://lttng.org)
- Network storage system (https://www.gluster.org/)
- Virtual routers (https://events.linuxfoundation.org/sites/events/files/slides/DPDK_RCU_0MQ.pdf)
- Financial software (https://lkml.org/lkml/2015/3/23/189)
Those projects use RCU in userspace to increase read-side speed and
scalability compared to locking. Especially in the case of RCU used by
libraries, sys_membarrier can speed up the read-side by moving the bulk of
the memory barrier cost to synchronize_rcu().
* Direct users of sys_membarrier
- core dotnet garbage collector (https://github.com/dotnet/coreclr/issues/198)
Microsoft core dotnet GC developers are planning to use the mprotect()
side-effect of issuing memory barriers through IPIs as a way to implement
Windows FlushProcessWriteBuffers() on Linux. They are referring to
sys_membarrier in their github thread, specifically stating that
sys_membarrier() is what they are looking for.
To explain the benefit of this scheme, let's introduce two example threads:
Thread A (non-frequent, e.g. executing liburcu synchronize_rcu())
Thread B (frequent, e.g. executing liburcu
rcu_read_lock()/rcu_read_unlock())
In a scheme where all smp_mb() in thread A are ordering memory accesses
with respect to smp_mb() present in Thread B, we can change each
smp_mb() within Thread A into calls to sys_membarrier() and each
smp_mb() within Thread B into compiler barriers "barrier()".
Before the change, we had, for each smp_mb() pairs:
Thread A Thread B
previous mem accesses previous mem accesses
smp_mb() smp_mb()
following mem accesses following mem accesses
After the change, these pairs become:
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accesses
As we can see, there are two possible scenarios: either Thread B memory
accesses do not happen concurrently with Thread A accesses (1), or they
do (2).
1) Non-concurrent Thread A vs Thread B accesses:
Thread A Thread B
prev mem accesses
sys_membarrier()
follow mem accesses
prev mem accesses
barrier()
follow mem accesses
In this case, thread B accesses will be weakly ordered. This is OK,
because at that point, thread A is not particularly interested in
ordering them with respect to its own accesses.
2) Concurrent Thread A vs Thread B accesses
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accesses
In this case, thread B accesses, which are ensured to be in program
order thanks to the compiler barrier, will be "upgraded" to full
smp_mb() by synchronize_sched().
* Benchmarks
On Intel Xeon E5405 (8 cores)
(one thread is calling sys_membarrier, the other 7 threads are busy
looping)
1000 non-expedited sys_membarrier calls in 33s =3D 33 milliseconds/call.
* User-space user of this system call: Userspace RCU library
Both the signal-based and the sys_membarrier userspace RCU schemes
permit us to remove the memory barrier from the userspace RCU
rcu_read_lock() and rcu_read_unlock() primitives, thus significantly
accelerating them. These memory barriers are replaced by compiler
barriers on the read-side, and all matching memory barriers on the
write-side are turned into an invocation of a memory barrier on all
active threads in the process. By letting the kernel perform this
synchronization rather than dumbly sending a signal to every process
threads (as we currently do), we diminish the number of unnecessary wake
ups and only issue the memory barriers on active threads. Non-running
threads do not need to execute such barrier anyway, because these are
implied by the scheduler context switches.
Results in liburcu:
Operations in 10s, 6 readers, 2 writers:
memory barriers in reader: 1701557485 reads, 2202847 writes
signal-based scheme: 9830061167 reads, 6700 writes
sys_membarrier: 9952759104 reads, 425 writes
sys_membarrier (dyn. check): 7970328887 reads, 425 writes
The dynamic sys_membarrier availability check adds some overhead to
the read-side compared to the signal-based scheme, but besides that,
sys_membarrier slightly outperforms the signal-based scheme. However,
this non-expedited sys_membarrier implementation has a much slower grace
period than signal and memory barrier schemes.
Besides diminishing the number of wake-ups, one major advantage of the
membarrier system call over the signal-based scheme is that it does not
need to reserve a signal. This plays much more nicely with libraries,
and with processes injected into for tracing purposes, for which we
cannot expect that signals will be unused by the application.
An expedited version of this system call can be added later on to speed
up the grace period. Its implementation will likely depend on reading
the cpu_curr()->mm without holding each CPU's rq lock.
This patch adds the system call to x86 and to asm-generic.
[1] http://urcu.so
membarrier(2) man page:
MEMBARRIER(2) Linux Programmer's Manual MEMBARRIER(2)
NAME
membarrier - issue memory barriers on a set of threads
SYNOPSIS
#include <linux/membarrier.h>
int membarrier(int cmd, int flags);
DESCRIPTION
The cmd argument is one of the following:
MEMBARRIER_CMD_QUERY
Query the set of supported commands. It returns a bitmask of
supported commands.
MEMBARRIER_CMD_SHARED
Execute a memory barrier on all threads running on the system.
Upon return from system call, the caller thread is ensured that
all running threads have passed through a state where all memory
accesses to user-space addresses match program order between
entry to and return from the system call (non-running threads
are de facto in such a state). This covers threads from all pro=E2=80=90
cesses running on the system. This command returns 0.
The flags argument needs to be 0. For future extensions.
All memory accesses performed in program order from each targeted
thread is guaranteed to be ordered with respect to sys_membarrier(). If
we use the semantic "barrier()" to represent a compiler barrier forcing
memory accesses to be performed in program order across the barrier,
and smp_mb() to represent explicit memory barriers forcing full memory
ordering across the barrier, we have the following ordering table for
each pair of barrier(), sys_membarrier() and smp_mb():
The pair ordering is detailed as (O: ordered, X: not ordered):
barrier() smp_mb() sys_membarrier()
barrier() X X O
smp_mb() X O O
sys_membarrier() O O O
RETURN VALUE
On success, these system calls return zero. On error, -1 is returned,
and errno is set appropriately. For a given command, with flags
argument set to 0, this system call is guaranteed to always return the
same value until reboot.
ERRORS
ENOSYS System call is not implemented.
EINVAL Invalid arguments.
Linux 2015-04-15 MEMBARRIER(2)
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Miell <nmiell@comcast.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pm-cpu:
kernel/cpu_pm: fix cpu_cluster_pm_exit comment
* pm-cpuidle:
cpuidle/coupled: Add sanity check for safe_state_index
* pm-domains:
staging: board: Migrate away from __pm_genpd_name_add_device()
PM / Domains: Ensure subdomain is not in use before removing
PM / Domains: Try power off masters in error path of __pm_genpd_poweron()
Kernel testing triggered this warning:
| WARNING: CPU: 0 PID: 13 at kernel/sched/core.c:1156 do_set_cpus_allowed+0x7e/0x80()
| Modules linked in:
| CPU: 0 PID: 13 Comm: migration/0 Not tainted 4.2.0-rc1-00049-g25834c7 #2
| Call Trace:
| dump_stack+0x4b/0x75
| warn_slowpath_common+0x8b/0xc0
| warn_slowpath_null+0x22/0x30
| do_set_cpus_allowed+0x7e/0x80
| cpuset_cpus_allowed_fallback+0x7c/0x170
| select_fallback_rq+0x221/0x280
| migration_call+0xe3/0x250
| notifier_call_chain+0x53/0x70
| __raw_notifier_call_chain+0x1e/0x30
| cpu_notify+0x28/0x50
| take_cpu_down+0x22/0x40
| multi_cpu_stop+0xd5/0x140
| cpu_stopper_thread+0xbc/0x170
| smpboot_thread_fn+0x174/0x2f0
| kthread+0xc4/0xe0
| ret_from_kernel_thread+0x21/0x30
As Peterz pointed out:
| So the normal rules for changing task_struct::cpus_allowed are holding
| both pi_lock and rq->lock, such that holding either stabilizes the mask.
|
| This is so that wakeup can happen without rq->lock and load-balance
| without pi_lock.
|
| From this we already get the relaxation that we can omit acquiring
| rq->lock if the task is not on the rq, because in that case
| load-balancing will not apply to it.
|
| ** these are the rules currently tested in do_set_cpus_allowed() **
|
| Now, since __set_cpus_allowed_ptr() uses task_rq_lock() which
| unconditionally acquires both locks, we could get away with holding just
| rq->lock when on_rq for modification because that'd still exclude
| __set_cpus_allowed_ptr(), it would also work against
| __kthread_bind_mask() because that assumes !on_rq.
|
| That said, this is all somewhat fragile.
|
| Now, I don't think dropping rq->lock is quite as disastrous as it
| usually is because !cpu_active at this point, which means load-balance
| will not interfere, but that too is somewhat fragile.
|
| So we end up with a choice of two fragile..
This patch fixes it by following the rules for changing
task_struct::cpus_allowed with both pi_lock and rq->lock held.
Reported-by: kernel test robot <ying.huang@intel.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
[ Modified changelog and patch. ]
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>
Link: http://lkml.kernel.org/r/BLU436-SMTP1660820490DE202E3934ED3806E0@phx.gbl
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Dave ran into horrible performance on a VM without PARAVIRT_SPINLOCKS
set and Linus noted that the test-and-set implementation was retarded.
One should spin on the variable with a load, not a RMW.
While there, remove 'queued' from the name, as the lock isn't queued
at all, but a simple test-and-set.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Dave Chinner <david@fromorbit.com>
Tested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: stable@vger.kernel.org # v4.2+
Link: http://lkml.kernel.org/r/20150904152523.GR18673@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge third patch-bomb from Andrew Morton:
- even more of the rest of MM
- lib/ updates
- checkpatch updates
- small changes to a few scruffy filesystems
- kmod fixes/cleanups
- kexec updates
- a dma-mapping cleanup series from hch
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (81 commits)
dma-mapping: consolidate dma_set_mask
dma-mapping: consolidate dma_supported
dma-mapping: cosolidate dma_mapping_error
dma-mapping: consolidate dma_{alloc,free}_noncoherent
dma-mapping: consolidate dma_{alloc,free}_{attrs,coherent}
mm: use vma_is_anonymous() in create_huge_pmd() and wp_huge_pmd()
mm: make sure all file VMAs have ->vm_ops set
mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff()
mm: mark most vm_operations_struct const
namei: fix warning while make xmldocs caused by namei.c
ipc: convert invalid scenarios to use WARN_ON
zlib_deflate/deftree: remove bi_reverse()
lib/decompress_unlzma: Do a NULL check for pointer
lib/decompressors: use real out buf size for gunzip with kernel
fs/affs: make root lookup from blkdev logical size
sysctl: fix int -> unsigned long assignments in INT_MIN case
kexec: export KERNEL_IMAGE_SIZE to vmcoreinfo
kexec: align crash_notes allocation to make it be inside one physical page
kexec: remove unnecessary test in kimage_alloc_crash_control_pages()
kexec: split kexec_load syscall from kexec core code
...
Pull networking fixes from David Miller:
1) Fix out-of-bounds array access in netfilter ipset, from Jozsef
Kadlecsik.
2) Use correct free operation on netfilter conntrack templates, from
Daniel Borkmann.
3) Fix route leak in SCTP, from Marcelo Ricardo Leitner.
4) Fix sizeof(pointer) in mac80211, from Thierry Reding.
5) Fix cache pointer comparison in ip6mr leading to missed unlock of
mrt_lock. From Richard Laing.
6) rds_conn_lookup() needs to consider network namespace in key
comparison, from Sowmini Varadhan.
7) Fix deadlock in TIPC code wrt broadcast link wakeups, from Kolmakov
Dmitriy.
8) Fix fd leaks in bpf syscall, from Daniel Borkmann.
9) Fix error recovery when installing ipv6 multipath routes, we would
delete the old route before we would know if we could fully commit
to the new set of nexthops. Fix from Roopa Prabhu.
10) Fix run-time suspend problems in r8152, from Hayes Wang.
11) In fec, don't program the MAC address into the chip when the clocks
are gated off. From Fugang Duan.
12) Fix poll behavior for netlink sockets when using rx ring mmap, from
Daniel Borkmann.
13) Don't allocate memory with GFP_KERNEL from get_stats64 in r8169
driver, from Corinna Vinschen.
14) In TCP Cubic congestion control, handle idle periods better where we
are application limited, in order to keep cwnd from growing out of
control. From Eric Dumzet.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (65 commits)
tcp_cubic: better follow cubic curve after idle period
tcp: generate CA_EVENT_TX_START on data frames
xen-netfront: respect user provided max_queues
xen-netback: respect user provided max_queues
r8169: Fix sleeping function called during get_stats64, v2
ether: add IEEE 1722 ethertype - TSN
netlink, mmap: fix edge-case leakages in nf queue zero-copy
netlink, mmap: don't walk rx ring on poll if receive queue non-empty
cxgb4: changes for new firmware 1.14.4.0
net: fec: add netif status check before set mac address
r8152: fix the runtime suspend issues
r8152: split DRIVER_VERSION
ipv6: fix ifnullfree.cocci warnings
add microchip LAN88xx phy driver
stmmac: fix check for phydev being open
net: qlcnic: delete redundant memsets
net: mv643xx_eth: use kzalloc
net: jme: use kzalloc() instead of kmalloc+memset
net: cavium: liquidio: use kzalloc in setup_glist()
net: ipv6: use common fib_default_rule_pref
...
The following
if (val < 0)
*lvalp = (unsigned long)-val;
is incorrect because the compiler is free to assume -val to be positive
and use a sign-extend instruction for extending the bit pattern. This is
a problem if val == INT_MIN:
# echo -2147483648 >/proc/sys/dev/scsi/logging_level
# cat /proc/sys/dev/scsi/logging_level
-18446744071562067968
Cast to unsigned long before negation - that way we first sign-extend and
then negate an unsigned, which is well defined. With this:
# cat /proc/sys/dev/scsi/logging_level
-2147483648
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Cc: Mikulas Patocka <mikulas@twibright.com>
Cc: Robert Xiao <nneonneo@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
