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Fixed an inconsistent use of GFP flags in nft_obj_notify() that used
GFP_KERNEL when a GFP flag was passed in to that function. Given this
allocated memory was then used in audit_log_nfcfg() it led to an audit
of all other GFP allocations in net/netfilter/nf_tables_api.c and a
modification of audit_log_nfcfg() to accept a GFP parameter.
Reported-by: Dan Carptenter <dan.carpenter@oracle.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Disable branch tracing in core KCSAN runtime if branches are being
traced (TRACE_BRANCH_PROFILING). This it to avoid its performance
impact, but also avoid recursion in case KCSAN is enabled for the branch
tracing runtime.
The latter had already been a problem for KASAN:
https://lore.kernel.org/lkml/CANpmjNOeXmD5E3O50Z3MjkiuCYaYOPyi+1rq=GZvEKwBvLR0Ug@mail.gmail.com/
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Simplify the set of compiler flags for the runtime by removing cc-option
from -fno-stack-protector, because all supported compilers support it.
This saves us one compiler invocation during build.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Add a test that KCSAN nor the compiler gets confused about accesses to
jiffies on different architectures.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Remove existing special atomic rules from kcsan_is_atomic_special()
because they are no longer needed. Since we rely on the compiler
emitting instrumentation distinguishing volatile accesses, the rules
have become redundant.
Let's keep kcsan_is_atomic_special() around, so that we have an obvious
place to add special rules should the need arise in future.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Rename 'test.c' to 'selftest.c' to better reflect its purpose (Kconfig
variable and code inside already match this). This is to avoid confusion
with the test suite module in 'kcsan-test.c'.
No functional change.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The functions here should not be forward declared for explicit use
elsewhere in the kernel, as they should only be emitted by the compiler
due to sanitizer instrumentation. Add forward declarations a line above
their definition to shut up warnings in W=1 builds.
Link: https://lkml.kernel.org/r/202006060103.jSCpnV1g%lkp@intel.com
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Instead of __no_kcsan_or_inline, prefer '__no_kcsan inline' in test --
this is in case we decide to remove __no_kcsan_or_inline.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The prev->next pointer can be accessed concurrently as noticed by KCSAN:
write (marked) to 0xffff9d3370dbbe40 of 8 bytes by task 3294 on cpu 107:
osq_lock+0x25f/0x350
osq_wait_next at kernel/locking/osq_lock.c:79
(inlined by) osq_lock at kernel/locking/osq_lock.c:185
rwsem_optimistic_spin
<snip>
read to 0xffff9d3370dbbe40 of 8 bytes by task 3398 on cpu 100:
osq_lock+0x196/0x350
osq_lock at kernel/locking/osq_lock.c:157
rwsem_optimistic_spin
<snip>
Since the write only stores NULL to prev->next and the read tests if
prev->next equals to this_cpu_ptr(&osq_node). Even if the value is
shattered, the code is still working correctly. Thus, mark it as an
intentional data race using the data_race() macro.
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This adds KCSAN test focusing on behaviour of the integrated runtime.
Tests various race scenarios, and verifies the reports generated to
console. Makes use of KUnit for test organization, and the Torture
framework for test thread control.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
struct vm_area_struct could be accessed concurrently as noticed by
KCSAN,
write to 0xffff9cf8bba08ad8 of 8 bytes by task 14263 on cpu 35:
vma_interval_tree_insert+0x101/0x150:
rb_insert_augmented_cached at include/linux/rbtree_augmented.h:58
(inlined by) vma_interval_tree_insert at mm/interval_tree.c:23
__vma_link_file+0x6e/0xe0
__vma_link_file at mm/mmap.c:629
vma_link+0xa2/0x120
mmap_region+0x753/0xb90
do_mmap+0x45c/0x710
vm_mmap_pgoff+0xc0/0x130
ksys_mmap_pgoff+0x1d1/0x300
__x64_sys_mmap+0x33/0x40
do_syscall_64+0x91/0xc44
entry_SYSCALL_64_after_hwframe+0x49/0xbe
read to 0xffff9cf8bba08a80 of 200 bytes by task 14262 on cpu 122:
vm_area_dup+0x6a/0xe0
vm_area_dup at kernel/fork.c:362
__split_vma+0x72/0x2a0
__split_vma at mm/mmap.c:2661
split_vma+0x5a/0x80
mprotect_fixup+0x368/0x3f0
do_mprotect_pkey+0x263/0x420
__x64_sys_mprotect+0x51/0x70
do_syscall_64+0x91/0xc44
entry_SYSCALL_64_after_hwframe+0x49/0xbe
vm_area_dup() blindly copies all fields of original VMA to the new one.
This includes coping vm_area_struct::shared.rb which is normally
protected by i_mmap_lock. But this is fine because the read value will
be overwritten on the following __vma_link_file() under proper
protection. Thus, mark it as an intentional data race and insert a few
assertions for the fields that should not be modified concurrently.
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
If there is a large number of torture tests running concurrently,
all of which are dumping large ftrace buffers at shutdown time, the
resulting dumping can take a very long time, particularly on systems
with rotating-rust storage. This commit therefore adds a default-off
torture.ftrace_dump_at_shutdown module parameter that enables
shutdown-time ftrace-buffer dumping.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
RCU is supposed to be watching all non-idle kernel code and also all
softirq handlers. This commit adds some teeth to this statement by
adding a WARN_ON_ONCE().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Coccinelle reports a warning
WARNING: Assignment of 0/1 to bool variable
The root cause is that the variable lastphase is a bool, but is
initialised with integer 0. This commit therefore replaces the 0 with
a false.
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, the rcu_torture_current variable remains non-NULL until after
all readers have stopped. During this time, rcu_torture_stats_print()
will think that the test is still ongoing, which can result in confusing
dmesg output. This commit therefore NULLs rcu_torture_current immediately
after the rcu_torture_writer() kthread has decided to stop, thus informing
rcu_torture_stats_print() much sooner.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Several variants of Linux-kernel RCU interact with task-exit processing,
including preemptible RCU, Tasks RCU, and Tasks Trace RCU. This commit
therefore adds testing of this interaction to rcutorture by adding
rcutorture.read_exit_burst and rcutorture.read_exit_delay kernel-boot
parameters. These kernel parameters control the frequency and spacing
of special read-then-exit kthreads that are spawned.
[ paulmck: Apply feedback from Dan Carpenter's static checker. ]
[ paulmck: Reduce latency to avoid false-positive shutdown hangs. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit fixes the following coccicheck warnings:
kernel/locking/locktorture.c:689:6-10: WARNING: Assignment of 0/1 to bool variable
kernel/locking/locktorture.c:907:2-20: WARNING: Assignment of 0/1 to bool variable
kernel/locking/locktorture.c:938:3-20: WARNING: Assignment of 0/1 to bool variable
kernel/locking/locktorture.c:668:2-19: WARNING: Assignment of 0/1 to bool variable
kernel/locking/locktorture.c:674:2-19: WARNING: Assignment of 0/1 to bool variable
kernel/locking/locktorture.c:634:2-20: WARNING: Assignment of 0/1 to bool variable
kernel/locking/locktorture.c:640:2-20: WARNING: Assignment of 0/1 to bool variable
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
SRCU disables interrupts to get a stable per-CPU pointer and then
acquires the spinlock which is in the per-CPU data structure. The
release uses spin_unlock_irqrestore(). While this is correct on a non-RT
kernel, this conflicts with the RT semantics because the spinlock is
converted to a 'sleeping' spinlock. Sleeping locks can obviously not be
acquired with interrupts disabled.
Acquire the per-CPU pointer `ssp->sda' without disabling preemption and
then acquire the spinlock_t of the per-CPU data structure. The lock will
ensure that the data is consistent.
The added call to check_init_srcu_struct() is now needed because a
statically defined srcu_struct may remain uninitialized until this
point and the newly introduced locking operation requires an initialized
spinlock_t.
This change was tested for four hours with 8*SRCU-N and 8*SRCU-P without
causing any warnings.
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: rcu@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit further avoids conflation of refperf with the kernel's perf
feature by renaming kernel/rcu/refperf.c to kernel/rcu/refscale.c,
and also by similarly renaming the functions and variables inside
this file. This has the side effect of changing the names of the
kernel boot parameters, so kernel-parameters.txt and ver_functions.sh
are also updated.
The rcutorture --torture type remains refperf, and this will be
addressed in a separate commit.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The old Kconfig option name is all too easy to conflate with the
unrelated "perf" feature, so this commit renames RCU_REF_PERF_TEST to
RCU_REF_SCALE_TEST.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The synchronize_rcu_tasks_trace() header comment incorrectly claims that
any number of things delimit RCU Tasks Trace read-side critical sections,
when in fact only rcu_read_lock_trace() and rcu_read_unlock_trace() do so.
This commit therefore fixes this comment, and, while in the area, fixes
a typo in the rcu_read_lock_trace() header comment.
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds testing for RCU Tasks readers to the refperf module.
This also applies to RCU Rude readers, as both flavors have empty
(as in non-existent) read-side markers.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The current units of microseconds are too coarse, so this commit
changes the units to nanoseconds. However, ndelay is used only for the
nanoseconds with udelay being used for whole microseconds. For example,
setting refperf.readdelay=1500 results in a udelay(1) followed by an
ndelay(500).
Suggested-by: Akira Yokosawa <akiyks@gmail.com>
[ paulmck: Abstracted delay per Akira feedback and move from 80 to 100 lines. ]
[ paulmck: Fix names as suggested by kbuild test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
A 64-bit division was introduced in refperf, breaking compilation
on all 32-bit architectures:
kernel/rcu/refperf.o: in function `main_func':
refperf.c:(.text+0x57c): undefined reference to `__aeabi_uldivmod'
Fix this by using div_u64 to mark the expensive operation.
[ paulmck: Update primitive and format per Nathan Chancellor. ]
Fixes: bd5b16d6c88d ("refperf: Allow decimal nanoseconds")
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Valdis Klētnieks <valdis.kletnieks@vt.edu>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
With the various measurement optimizations, 10,000 loops normally
suffices. This commit therefore reduces the refperf.loops default value
from 10,000,000 to 10,000.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds a refperf.readdelay module parameter that controls the
duration of each critical section. This parameter allows gathering data
showing how the performance differences between the various primitives
vary with critical-section length.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit moves the reader-launch wait loop from ref_perf_init()
to main_func(), removing one layer of wakeup and allowing slightly
faster system boot.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The experiment-number column is currently labeled "Threads", which is
misleading at best. This commit therefore relabels it as "Runs", and
adjusts the scripts accordingly.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit causes all the readers to start running unmeasured load
until all readers have done at least one such run (thus having warmed
up), then run the measured load, and then run unmeasured load until all
readers have completed their measured load. This approach avoids any
thread running measured load while other readers are idle.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, readers are awakened individually. On most systems, this
results in significant wakeup delay from one reader to the next, which
can result in the first and last reader having sole access to the
synchronization primitive in question. If that synchronization primitive
involves shared memory, those readers will rack up a huge number of
operations in a very short time, causing large perturbations in the
results.
This commit therefore has the readers busy-wait after being awakened,
and uses a new n_started variable to synchronize their start times.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit converts the reader_task structure's "start" field to int
in order to demote a full barrier to an smp_load_acquire() and also to
simplify the code a bit. While in the area, and to enlist the compiler's
help in ensuring that nothing was missed, the field's name was changed
to start_reader.
Also while in the area, change the main_func() store to use
smp_store_release() to further fortify against wait/wake races.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit moves a printk() out of the measurement interval, converts
a atomic_dec()/atomic_read() pair to atomic_dec_and_test(), and adds
a smp_mb__before_atomic() to avoid potential wake/wait hangs. These
changes have the added benefit of reducing the number of loops required
for amortizing loop overhead for CONFIG_PREEMPT=n RCU measurements from
1,000,000 to 10,000. This reduction in turn shortens the test, reducing
the probability of interference.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Because the reset_readers() and process_durations() functions are used
only within kernel/rcu/refperf.c, this commit makes them static.
Reported-by: kbuild test robot <lkp@intel.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, the buffer used to accumulate the thread-summary output is
fixed size, which will cause problems if someone decides to run on a large
number of PCUs. This commit therefore dynamically allocates this buffer.
[ paulmck: Fix memory allocation as suggested by KASAN. ]
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, the buffer used to accumulate the experiment-summary output
is fixed size, which will cause problems if someone decides to run
one hundred experiments. This commit therefore dynamically allocates
this buffer.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The current code uses the number of threads both to limit the number
of threads and to specify the number of experiments, but also varies
the number of threads as the experiments progress. This commit takes
a different approach by adding an refperf.nruns module parameter that
specifies the number of experiments, and furthermore uses the same
number of threads for each experiment.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit converts nreaders to a module parameter, with the default
of -1 specifying the old behavior of using 75% of the readers.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The CONFIG_PREEMPT=n rcu_read_lock()/rcu_read_unlock() pair's overhead,
even including loop overhead, is far less than one nanosecond.
Since logscale plots are not all that happy with zero values, provide
picoseconds as decimals.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Current runs show PREEMPT=n rcu_read_lock()/rcu_read_unlock() pairs
consuming between 20 and 30 nanoseconds, when in fact the actual value is
zero, give or take the barrier() asm's effect on compiler optimizations.
The additional overhead is caused by function calls through pointers
(especially in these days of Spectre mitigations) and perhaps also
needless argument passing, a non-const loop limit, and an upcounting loop.
This commit therefore combines the ->readlock() and ->readunlock()
function pointers into a single ->readsection() function pointer that
takes the loop count as a const parameter and keeps any data passed
from the read-lock to the read-unlock internal to this new function.
These changes reduce the measured overhead of the aforementioned
PREEMPT=n rcu_read_lock()/rcu_read_unlock() pairs from between 20 and
30 nanoseconds to somewhere south of 500 picoseconds.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds an rcuperf module parameter named "holdoff" that
defaults to 10 seconds if refperf is built in and to zero otherwise.
The assumption is that all the CPUs are online by the time that the
modprobe and insmod commands are going to do anything, and that normal
systems will have all the CPUs online within ten seconds.
Larger systems may take many tens of seconds or even minutes to get
to this point, hence this being a module parameter instead of being a
hard-coded constant.
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds comments explaining why the readers have otherwise insane
levels of measurement overhead, namely that they are intended as a test
load for update-side performance measurements, not as a straight-up
read-side performance test.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Add a test for comparing the performance of RCU with various read-side
synchronization mechanisms. The test has proved useful for collecting
data and performing these comparisons.
Currently RCU, SRCU, reader-writer lock, reader-writer semaphore and
reference counting can be measured using refperf.perf_type parameter.
Each invocation of the test runs measures performance of a specific
mechanism.
The maximum number of CPUs to concurrently run readers on is chosen by
the test itself and is 75% of the total number of CPUs. So if you had 24
CPUs, the test runs with a maximum of 18 parallel readers.
A number of experiments are conducted, and in each experiment, the
number of readers is increased by 1, upto the 75% of CPUs mark. During
each experiment, all readers execute an empty loop with refperf.loops
iterations and time the total loop duration. This is then averaged.
Example output:
Parameters "refperf.perf_type=srcu refperf.loops=2000000" looks like:
[ 3.347133] srcu-ref-perf:
[ 3.347133] Threads Time(ns)
[ 3.347133] 1 36
[ 3.347133] 2 34
[ 3.347133] 3 34
[ 3.347133] 4 34
[ 3.347133] 5 33
[ 3.347133] 6 33
[ 3.347133] 7 33
[ 3.347133] 8 33
[ 3.347133] 9 33
[ 3.347133] 10 33
[ 3.347133] 11 33
[ 3.347133] 12 33
[ 3.347133] 13 33
[ 3.347133] 14 33
[ 3.347133] 15 32
[ 3.347133] 16 33
[ 3.347133] 17 33
[ 3.347133] 18 34
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
wait_event() already retries if the condition for the wake up is not
satisifed after wake up. Remove them from the rcuperf test.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit declares trc_n_readers_need_end and trc_wait static and
replaced a "&" with "&&". The "&" happened to work because the values
are bool, but accidents waiting to happen and all that...
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The show_rcu_tasks_gp_kthreads() function is not invoked by Tiny RCU,
but is nevertheless defined in Tiny RCU builds that enable Tasks Trace
RCU. This commit therefore conditionally compiles this function so
that it is defined only in builds that actually use it.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Although this is in some strict sense unnecessary, it is good to allow
the compiler to compare the function declaration with its definition.
This commit therefore adds a #include of linux/rcupdate_trace.h to
kernel/rcu/update.c.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The rcu_tasks_postscan() function is not used outside of RCU's tasks.h
file, so this commit makes it be static.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
