Commit Graph

34110 Commits

Author SHA1 Message Date
Paul E. McKenney
f511ce1424 Merge branch 'scftorture.2020.08.24a' into HEAD
scftorture.2020.08.24a: Torture tests for smp_call_function() and friends.
2020-09-03 09:47:01 -07:00
Paul E. McKenney
cfb2c1070a Merge branches 'doc.2020.08.24a', 'fixes.2020.09.03b' and 'torture.2020.08.24a' into HEAD
doc.2020.08.24a: Documentation updates.
fixes.2020.09.03b: Miscellaneous fixes.
torture.2020.08.24a: Torture-test updates.
2020-09-03 09:42:02 -07:00
Zqiang
70060b8770 rcu: Shrink each possible cpu krcp
CPUs can go offline shortly after kfree_call_rcu() has been invoked,
which can leave memory stranded until those CPUs come back online.
This commit therefore drains the kcrp of each CPU, not just the
ones that happen to be online.

Acked-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-09-03 09:40:13 -07:00
Joel Fernandes (Google)
53922270d2 rcu/segcblist: Prevent useless GP start if no CBs to accelerate
The rcu_segcblist_accelerate() function returns true iff it is necessary
to request another grace period.  A tracing session showed that this
function unnecessarily requests grace periods.

For example, consider the following sequence of events:
1. Callbacks are queued only on the NEXT segment of CPU A's callback list.
2. CPU A runs RCU_SOFTIRQ, accelerating these callbacks from NEXT to WAIT.
3. Thus rcu_segcblist_accelerate() returns true, requesting grace period N.
4. RCU's grace-period kthread wakes up on CPU B and starts grace period N.
4. CPU A notices the new grace period and invokes RCU_SOFTIRQ.
5. CPU A's RCU_SOFTIRQ again invokes rcu_segcblist_accelerate(), but
   there are no new callbacks.  However, rcu_segcblist_accelerate()
   nevertheless (uselessly) requests a new grace period N+1.

This extra grace period results in additional lock contention and also
additional wakeups, all for no good reason.

This commit therefore adds a check to rcu_segcblist_accelerate() that
prevents the return of true when there are no new callbacks.

This change reduces the number of grace periods (GPs) and wakeups in each
of eleven five-second rcutorture runs as follows:

+----+-------------------+-------------------+
| #  | Number of GPs     | Number of Wakeups |
+====+=========+=========+=========+=========+
| 1  | With    | Without | With    | Without |
+----+---------+---------+---------+---------+
| 2  |      75 |      89 |     113 |     119 |
+----+---------+---------+---------+---------+
| 3  |      62 |      91 |     105 |     123 |
+----+---------+---------+---------+---------+
| 4  |      60 |      79 |      98 |     110 |
+----+---------+---------+---------+---------+
| 5  |      63 |      79 |      99 |     112 |
+----+---------+---------+---------+---------+
| 6  |      57 |      89 |      96 |     123 |
+----+---------+---------+---------+---------+
| 7  |      64 |      85 |      97 |     118 |
+----+---------+---------+---------+---------+
| 8  |      58 |      83 |      98 |     113 |
+----+---------+---------+---------+---------+
| 9  |      57 |      77 |      89 |     104 |
+----+---------+---------+---------+---------+
| 10 |      66 |      82 |      98 |     119 |
+----+---------+---------+---------+---------+
| 11 |      52 |      82 |      83 |     117 |
+----+---------+---------+---------+---------+

The reduction in the number of wakeups ranges from 5% to 40%.

Cc: urezki@gmail.com
[ paulmck: Rework commit log and comment. ]
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-09-03 09:39:59 -07:00
Paul E. McKenney
d685514260 rcutorture: Allow pointer leaks to test diagnostic code
This commit adds an rcutorture.leakpointer module parameter that
intentionally leaks an RCU-protected pointer out of the RCU read-side
critical section and checks to see if the corresponding grace period
has elapsed, emitting a WARN_ON_ONCE() if so.  This module parameter can
be used to test facilities like CONFIG_RCU_STRICT_GRACE_PERIOD that end
grace periods quickly.

While in the area, also document rcutorture.irqreader, which was
previously left out.

Reported-by Jann Horn <jannh@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:36 -07:00
Paul E. McKenney
299c7d94f6 rcutorture: Hoist OOM registry up one level
Currently, registering and unregistering the OOM notifier is done
right before and after the test, respectively.  This will not work
well for multi-threaded tests, so this commit hoists this registering
and unregistering up into the rcu_torture_fwd_prog_init() and
rcu_torture_fwd_prog_cleanup() functions.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:35 -07:00
Colin Ian King
58db5785b0 refperf: Avoid null pointer dereference when buf fails to allocate
Currently in the unlikely event that buf fails to be allocated it
is dereferenced a few times.  Use the errexit flag to determine if
buf should be written to to avoid the null pointer dereferences.

Addresses-Coverity: ("Dereference after null check")
Fixes: f518f154ec ("refperf: Dynamically allocate experiment-summary output buffer")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:35 -07:00
Paul E. McKenney
57f602022e rcutorture: Properly synchronize with OOM notifier
The current rcutorture forward-progress code assumes that it is the
only cause of out-of-memory (OOM) events.  For script-based rcutorture
testing, this assumption is in fact correct.  However, testing based
on modprobe/rmmod might well encounter external OOM events, which could
happen at any time.

This commit therefore properly synchronizes the interaction between
rcutorture's forward-progress testing and its OOM notifier by adding a
global mutex.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:34 -07:00
Paul E. McKenney
c8fa637147 rcutorture: Properly set rcu_fwds for OOM handling
The conversion of rcu_fwds to dynamic allocation failed to actually
allocate the required structure.  This commit therefore allocates it,
frees it, and updates rcu_fwds accordingly.  While in the area, it
abstracts the cleanup actions into rcu_torture_fwd_prog_cleanup().

Fixes: 5155be9994 ("rcutorture: Dynamically allocate rcu_fwds structure")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:34 -07:00
Wei Yongjun
d49bed9abc locktorture: Make function torture_percpu_rwsem_init() static
The sparse tool complains as follows:

kernel/locking/locktorture.c:569:6: warning:
 symbol 'torture_percpu_rwsem_init' was not declared. Should it be static?

And this function is not used outside of locktorture.c,
so this commit marks it static.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:32 -07:00
Joel Fernandes (Google)
959954df0c rcutorture: Output number of elapsed grace periods
This commit adds code to print the grace-period number at the start
of the test along with both the grace-period number and the number of
elapsed grace periods at the end of the test.  Note that variants of
RCU)without the notion of a grace-period number (for example, Tiny RCU)
just print zeroes.

[ paulmck: Adjust commit log. ]
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:31 -07:00
Paul E. McKenney
83224afd11 rcutorture: Remove KCSAN stubs
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:31 -07:00
Paul E. McKenney
4e88ec4a9e rcuperf: Change rcuperf to rcuscale
This commit further avoids conflation of rcuperf with the kernel's perf
feature by renaming kernel/rcu/rcuperf.c to kernel/rcu/rcuscale.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 was also updated from rcuperf
to rcuscale.

[ paulmck: Fix bugs located by Stephen Rothwell. ]
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:39:24 -07:00
Paul E. McKenney
65bd77f554 scftorture: Add cond_resched() to test loop
Although the test loop does randomly delay, which would provide quiescent
states and so forth, it is possible for there to be a series of long
smp_call_function*() handler runtimes with no delays, which results in
softlockup and RCU CPU stall warning messages.  This commit therefore
inserts a cond_resched() into the main test loop.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:38 -07:00
Paul E. McKenney
9e66bf03f9 scftorture: Adapt memory-ordering test to UP operation
On uniprocessor systems, smp_call_function() does nothing.  This commit
therefore avoids complaining about the lack of handler accesses in the
single-CPU case where there is no handler.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:37 -07:00
Paul E. McKenney
a7c072ef26 scftorture: Block scftorture_invoker() kthreads for offline CPUs
Currently, CPU-hotplug operations might result in all but two
of (say) 100 CPUs being offline, which in turn might result in
false-positive diagnostics due to overload.  This commit therefore
causes scftorture_invoker() kthreads for offline CPUs to loop blocking
for 200 milliseconds at a time, thus continuously adjusting the number
of threads to match the number of online CPUs.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:37 -07:00
Paul E. McKenney
de77d4da54 scftorture: Check unexpected "switch" statement value
This commit adds a "default" case to the switch statement in
scftorture_invoke_one() which contains a WARN_ON_ONCE() and an assignment
to ->scfc_out to suppress knock-on warnings.  These knock-on warnings
could otherwise cause the user to think that there was a memory-ordering
problem in smp_call_function() instead of a bug in scftorture.c itself.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:37 -07:00
Wei Yongjun
9a52a57467 scftorture: Make symbol 'scf_torture_rand' static
The sparse tool complains as follows

kernel/scftorture.c:124:1: warning:
 symbol '__pcpu_scope_scf_torture_rand' was not declared. Should it be static?

And this per-CPU variable is not used outside of scftorture.c,
so this commit marks it static.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:36 -07:00
Paul E. McKenney
ee7035d295 scftorture: Prevent compiler from reducing race probabilities
Detecting smp_call_function() memory misordering requires close timing,
so it is necessary to have the checks immediately before and after
the call to the smp_call_function*() function under test.  This commit
therefore inserts barrier() calls to prevent the compiler from optimizing
memory-misordering detection down into the zone of extreme improbability.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:36 -07:00
Paul E. McKenney
dbf83b655a scftorture: Flag errors in torture-compatible manner
This commit prints error counts on the statistics line and also adds a
"!!!" if any of the counters are non-zero.  Allocation failures are
(somewhat) forgiven, but all other errors result in a "FAILURE" print
at the end of the test.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:35 -07:00
Paul E. McKenney
4df55bddc1 scftorture: Consolidate scftorture_invoke_one() scf_check initialization
This commit hoists much of the initialization of the scf_check
structure out of the switch statement, thus saving a few lines of code.
The initialization of the ->scfc_in field remains in each leg of the
switch statement in order to more heavily stress memory ordering.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:35 -07:00
Paul E. McKenney
676e546964 scftorture: Consolidate scftorture_invoke_one() check and kfree()
This commit moves checking of the ->scfc_out field and the freeing of
the scf_check structure down below the end of switch statement, thus
saving a few lines of code.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:35 -07:00
Paul E. McKenney
34e8c4837a scftorture: Add smp_call_function() memory-ordering checks
This commit adds checks for memory misordering across calls to and
returns from smp_call_function() in the case where the caller waits.
Misordering results in a splat.

Note that in contrast to smp_call_function_single(), this code does not
test memory ordering into the handler in the no-wait case because none
of the handlers would be able to free the scf_check structure without
introducing heavy synchronization to work out which was last.

[ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:34 -07:00
Paul E. McKenney
980205ee84 scftorture: Add smp_call_function_many() memory-ordering checks
This commit adds checks for memory misordering across calls to and
returns from smp_call_function_many() in the case where the caller waits.
Misordering results in a splat.

Note that in contrast to smp_call_function_single(), this code does not
test memory ordering into the handler in the no-wait case because none
of the handlers would be able to free the scf_check structure without
introducing heavy synchronization to work out which was last.

[ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:34 -07:00
Paul E. McKenney
b93e21a51e scftorture: Add smp_call_function_single() memory-ordering checks
This commit adds checks for memory misordering across calls to
smp_call_function_single() and also across returns in the case where
the caller waits.  Misordering results in a splat.

[ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:33 -07:00
Paul E. McKenney
dba3142b37 scftorture: Summarize per-thread statistics
This commit summarizes the per-thread statistics, providing counts of
the number of single, many, and all calls, both no-wait and wait, and,
for the single case, the number where the target CPU was offline.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:33 -07:00
Paul E. McKenney
bca37119c5 tick-sched: Clarify "NOHZ: local_softirq_pending" warning
Currently, can_stop_idle_tick() prints "NOHZ: local_softirq_pending HH"
(where "HH" is the hexadecimal softirq vector number) when one or more
non-RCU softirq handlers are still enabled when checking to stop the
scheduler-tick interrupt.  This message is not as enlightening as one
might hope, so this commit changes it to "NOHZ tick-stop error: Non-RCU
local softirq work is pending, handler #HH".

Reported-by: Andy Lutomirski <luto@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:32 -07:00
Paul E. McKenney
5022b8ac60 scftorture: Implement weighted primitive selection
This commit uses the scftorture.weight* kernel parameters to randomly
chooses between smp_call_function_single(), smp_call_function_many(),
and smp_call_function().  For each variant, it also randomly chooses
whether to invoke it synchronously (wait=1) or asynchronously (wait=0).
The percentage weighting for each option are dumped to the console log
(search for "scf_sel_dump").

This accumulates statistics, which a later commit will dump out at the
end of the run.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:32 -07:00
Paul E. McKenney
e9d338a0b1 scftorture: Add smp_call_function() torture test
This commit adds an smp_call_function() torture test that repeatedly
invokes this function and complains if things go badly awry.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:38:31 -07:00
Paul E. McKenney
7f2a53c231 rcu: Remove unused __rcu_is_watching() function
The x86/entry work removed all uses of __rcu_is_watching(), therefore
this commit removes it entirely.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <x86@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:37:56 -07:00
Joel Fernandes (Google)
666ca2907e rcu: Make FQS more aggressive in complaining about offline CPUs
The RCU grace-period kthread's force-quiescent state (FQS) loop should
never see an offline CPU that has not yet reported a quiescent state.
After all, the offline CPU should have reported a quiescent state
during the CPU-offline process, or, failing that, by rcu_gp_init()
if it ran concurrently with either the CPU going offline or the last
task on a leaf rcu_node structure exiting its RCU read-side critical
section while all CPUs corresponding to that structure are offline.
The FQS loop should therefore complain if it does see an offline CPU
that has not yet reported a quiescent state.

And it does, but only once the grace period has been in force for a
full second.  This commit therefore makes this warning more aggressive,
so that it will trigger as soon as the condition makes its appearance.

Light testing with TREE03 and hotplug shows no warnings.  This commit
also converts the warning to WARN_ON_ONCE() in order to stave off possible
log spam.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:37:55 -07:00
Joel Fernandes (Google)
f37599e6f0 rcu: Clarify comments about FQS loop reporting quiescent states
Since at least v4.19, the FQS loop no longer reports quiescent states
for offline CPUs except in emergency situations.

This commit therefore fixes the comment in rcu_gp_init() to match the
current code.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:37:55 -07:00
Paul E. McKenney
4569c5ee95 rcu/nocb: Add a warning for non-GP kthread running GP code
This commit increases RCU's ability to defend itself by emitting a warning
if one of the nocb CB kthreads invokes the GP kthread's wait function.
This warning augments a similar check that is carried out at the end
of rcutorture testing and when RCU CPU stall warnings are emitted.
The problem with those checks is that the miscreants have long since
departed and disposed of any and all evidence.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:37:54 -07:00
Paul E. McKenney
c0f97f20e5 rcu: Move rcu_cpu_started per-CPU variable to rcu_data
When the rcu_cpu_started per-CPU variable was added by commit
f64c6013a2 ("rcu/x86: Provide early rcu_cpu_starting() callback"),
there were multiple sets of per-CPU rcu_data structures.  Therefore, the
rcu_cpu_started flag was added as a separate per-CPU variable.  But now
there is only one set of per-CPU rcu_data structures, so this commit
moves rcu_cpu_started to a new ->cpu_started field in that structure.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:37:54 -07:00
Paul E. McKenney
1ef5a442a1 rcu: Add READ_ONCE() to rcu_do_batch() access to rcu_cpu_stall_ftrace_dump
Given that sysfs can change the value of rcu_cpu_stall_ftrace_dump at any
time, this commit adds a READ_ONCE() to the accesses to that variable.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:08 -07:00
Paul E. McKenney
fe63b723cc rcu: Add READ_ONCE() to rcu_do_batch() access to rcu_kick_kthreads
Given that sysfs can change the value of rcu_kick_kthreads at any time,
this commit adds a READ_ONCE() to the sole access to that variable.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:07 -07:00
Paul E. McKenney
a2b354b995 rcu: Add READ_ONCE() to rcu_do_batch() access to rcu_resched_ns
Given that sysfs can change the value of rcu_resched_ns at any time,
this commit adds a READ_ONCE() to the sole access to that variable.
While in the area, this commit also adds bounds checking, clamping the
value to at least a millisecond, but no longer than a second.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:07 -07:00
Paul E. McKenney
b5374b2df0 rcu: Add READ_ONCE() to rcu_do_batch() access to rcu_divisor
Given that sysfs can change the value of rcu_divisor at any time, this
commit adds a READ_ONCE to the sole access to that variable.  While in
the area, this commit also adds bounds checking, clamping the value to
a shift that makes sense for a signed long.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:06 -07:00
Paul E. McKenney
2130c6b4f6 nocb: Remove show_rcu_nocb_state() false positive printout
The rcu_data structure's ->nocb_timer field is used to defer wakeups of
the corresponding no-CBs CPU's grace-period kthread ("rcuog*"), and that
structure's ->nocb_defer_wakeup field is used to track such deferral.
This means that the show_rcu_nocb_state() printing an error when those
fields are set for a CPU not corresponding to a no-CBs grace-period
kthread is erroneous.

This commit therefore switches the check from ->nocb_timer to
->nocb_bypass_timer and removes the check of ->nocb_defer_wakeup.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:06 -07:00
Neeraj Upadhyay
9b1ce0acb5 rcu/tree: Remove CONFIG_PREMPT_RCU check in force_qs_rnp()
Originally, the call to rcu_preempt_blocked_readers_cgp() from
force_qs_rnp() had to be conditioned on CONFIG_PREEMPT_RCU=y, as in
commit a77da14ce9 ("rcu: Yet another fix for preemption and CPU
hotplug").  However, there is now a CONFIG_PREEMPT_RCU=n definition of
rcu_preempt_blocked_readers_cgp() that unconditionally returns zero, so
invoking it is now safe.  In addition, the CONFIG_PREEMPT_RCU=n definition
of rcu_initiate_boost() simply releases the rcu_node structure's ->lock,
which is what happens when the "if" condition evaluates to false.

This commit therefore drops the IS_ENABLED(CONFIG_PREEMPT_RCU) check,
so that rcu_initiate_boost() is called only in CONFIG_PREEMPT_RCU=y
kernels when there are readers blocking the current grace period.
This does not change the behavior, but reduces code-reader confusion by
eliminating non-CONFIG_PREEMPT_RCU=y calls to rcu_initiate_boost().

Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:06 -07:00
Neeraj Upadhyay
9c39245382 rcu/tree: Force quiescent state on callback overload
On callback overload, it is necessary to quickly detect idle CPUs,
and rcu_gp_fqs_check_wake() checks for this condition.  Unfortunately,
the code following the call to this function does not repeat this check,
which means that in reality no actual quiescent-state forcing, instead
only a couple of quick and pointless wakeups at the beginning of the
grace period.

This commit therefore adds a check for the RCU_GP_FLAG_OVLD flag in
the post-wakeup "if" statement in rcu_gp_fqs_loop().

Fixes: 1fca4d12f4 ("rcu: Expedite first two FQS scans under callback-overload conditions")
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:05 -07:00
Paul E. McKenney
e082c7b381 nocb: Clarify RCU nocb CPU error message
A message of the form "rcu:    !!! lDTs ." can be tracked down, but
doing so is not trivial.  This commit therefore eases this process by
adding text so that this error message now reads as follows:
"rcu:    nocb GP activity on CB-only CPU!!! lDTs ."

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:05 -07:00
Joel Fernandes (Google)
a7886e899f rcu/trace: Use gp_seq_req in acceleration's rcu_grace_period tracepoint
During acceleration of CB, the rsp's gp_seq is rcu_seq_snap'd. This is
the value used for acceleration - it is the value of gp_seq at which it
is safe the execute all callbacks in the callback list.

The rdp's gp_seq is not very useful for this scenario. Make
rcu_grace_period report the gp_seq_req instead as it allows one to
reason about how the acceleration works.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:04 -07:00
Paul E. McKenney
7487ea07df rcu: Initialize at declaration time in rcu_exp_handler()
This commit moves the initialization of the CONFIG_PREEMPT=n version of
the rcu_exp_handler() function's rdp and rnp local variables into their
respective declarations to save a couple lines of code.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:03 -07:00
Paul E. McKenney
d9b6074131 srcu: Remove KCSAN stubs
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:03 -07:00
Paul E. McKenney
beb27bd649 rcu: Remove KCSAN stubs from update.c
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:03 -07:00
Paul E. McKenney
ebc3505d50 rcu: Remove KCSAN stubs
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:36:02 -07:00
Linus Torvalds
2cc3c4b3c2 io_uring-5.9-2020-08-15
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Merge tag 'io_uring-5.9-2020-08-15' of git://git.kernel.dk/linux-block

Pull io_uring fixes from Jens Axboe:
 "A few differerent things in here.

  Seems like syzbot got some more io_uring bits wired up, and we got a
  handful of reports and the associated fixes are in here.

  General fixes too, and a lot of them marked for stable.

  Lastly, a bit of fallout from the async buffered reads, where we now
  more easily trigger short reads. Some applications don't really like
  that, so the io_read() code now handles short reads internally, and
  got a cleanup along the way so that it's now easier to read (and
  documented). We're now passing tests that failed before"

* tag 'io_uring-5.9-2020-08-15' of git://git.kernel.dk/linux-block:
  io_uring: short circuit -EAGAIN for blocking read attempt
  io_uring: sanitize double poll handling
  io_uring: internally retry short reads
  io_uring: retain iov_iter state over io_read/io_write calls
  task_work: only grab task signal lock when needed
  io_uring: enable lookup of links holding inflight files
  io_uring: fail poll arm on queue proc failure
  io_uring: hold 'ctx' reference around task_work queue + execute
  fs: RWF_NOWAIT should imply IOCB_NOIO
  io_uring: defer file table grabbing request cleanup for locked requests
  io_uring: add missing REQ_F_COMP_LOCKED for nested requests
  io_uring: fix recursive completion locking on oveflow flush
  io_uring: use TWA_SIGNAL for task_work uncondtionally
  io_uring: account locked memory before potential error case
  io_uring: set ctx sq/cq entry count earlier
  io_uring: Fix NULL pointer dereference in loop_rw_iter()
  io_uring: add comments on how the async buffered read retry works
  io_uring: io_async_buf_func() need not test page bit
2020-08-16 10:55:12 -07:00
Linus Torvalds
5bbec3cfe3 Cleanup, SECCOMP_FILTER support, message printing fixes, and other
changes to arch/sh.
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Merge tag 'sh-for-5.9' of git://git.libc.org/linux-sh

Pull arch/sh updates from Rich Felker:
 "Cleanup, SECCOMP_FILTER support, message printing fixes, and other
  changes to arch/sh"

* tag 'sh-for-5.9' of git://git.libc.org/linux-sh: (34 commits)
  sh: landisk: Add missing initialization of sh_io_port_base
  sh: bring syscall_set_return_value in line with other architectures
  sh: Add SECCOMP_FILTER
  sh: Rearrange blocks in entry-common.S
  sh: switch to copy_thread_tls()
  sh: use the generic dma coherent remap allocator
  sh: don't allow non-coherent DMA for NOMMU
  dma-mapping: consolidate the NO_DMA definition in kernel/dma/Kconfig
  sh: unexport register_trapped_io and match_trapped_io_handler
  sh: don't include <asm/io_trapped.h> in <asm/io.h>
  sh: move the ioremap implementation out of line
  sh: move ioremap_fixed details out of <asm/io.h>
  sh: remove __KERNEL__ ifdefs from non-UAPI headers
  sh: sort the selects for SUPERH alphabetically
  sh: remove -Werror from Makefiles
  sh: Replace HTTP links with HTTPS ones
  arch/sh/configs: remove obsolete CONFIG_SOC_CAMERA*
  sh: stacktrace: Remove stacktrace_ops.stack()
  sh: machvec: Modernize printing of kernel messages
  sh: pci: Modernize printing of kernel messages
  ...
2020-08-15 18:50:32 -07:00
Linus Torvalds
50f6c7dbd9 Misc fixes and small updates all around the place:
- Fix mitigation state sysfs output
  - Fix an FPU xstate/sxave code assumption bug triggered by Architectural LBR support
  - Fix Lightning Mountain SoC TSC frequency enumeration bug
  - Fix kexec debug output
  - Fix kexec memory range assumption bug
  - Fix a boundary condition in the crash kernel code
 
  - Optimize porgatory.ro generation a bit
  - Enable ACRN guests to use X2APIC mode
  - Reduce a __text_poke() IRQs-off critical section for the benefit of PREEMPT_RT
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:
 "Misc fixes and small updates all around the place:

   - Fix mitigation state sysfs output

   - Fix an FPU xstate/sxave code assumption bug triggered by
     Architectural LBR support

   - Fix Lightning Mountain SoC TSC frequency enumeration bug

   - Fix kexec debug output

   - Fix kexec memory range assumption bug

   - Fix a boundary condition in the crash kernel code

   - Optimize porgatory.ro generation a bit

   - Enable ACRN guests to use X2APIC mode

   - Reduce a __text_poke() IRQs-off critical section for the benefit of
     PREEMPT_RT"

* tag 'x86-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/alternatives: Acquire pte lock with interrupts enabled
  x86/bugs/multihit: Fix mitigation reporting when VMX is not in use
  x86/fpu/xstate: Fix an xstate size check warning with architectural LBRs
  x86/purgatory: Don't generate debug info for purgatory.ro
  x86/tsr: Fix tsc frequency enumeration bug on Lightning Mountain SoC
  kexec_file: Correctly output debugging information for the PT_LOAD ELF header
  kexec: Improve & fix crash_exclude_mem_range() to handle overlapping ranges
  x86/crash: Correct the address boundary of function parameters
  x86/acrn: Remove redundant chars from ACRN signature
  x86/acrn: Allow ACRN guest to use X2APIC mode
2020-08-15 10:38:03 -07:00