scftorture: Handle NULL argument passed to scf_add_to_free_list().

Dan reported that after the rework the newly introduced
scf_add_to_free_list() may get a NULL pointer passed. This replaced
kfree()

scftorture: Handle NULL argument passed to scf_add_to_free_list().

Dan reported that after the rework the newly introduced
scf_add_to_free_list() may get a NULL pointer passed. This replaced
kfree() which was fine with a NULL pointer but scf_add_to_free_list()
isn't.

Let scf_add_to_free_list() handle NULL pointer.

Reported-by: Dan Carpenter <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]
Fixes: 4788c861ad7e9 ("scftorture: Use a lock-less list to free memory.")
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Use a lock-less list to free memory.

scf_handler() is used as a SMP function call. This function is always
invoked in IRQ-context even with forced-threading enabled. This function
frees

scftorture: Use a lock-less list to free memory.

scf_handler() is used as a SMP function call. This function is always
invoked in IRQ-context even with forced-threading enabled. This function
frees memory which not allowed on PREEMPT_RT because the locking
underneath is using sleeping locks.

Add a per-CPU scf_free_pool where each SMP functions adds its memory to
be freed. This memory is then freed by scftorture_invoker() on each
iteration. On the majority of invocations the number of items is less
than five. If the thread sleeps/ gets delayed the number exceed 350 but
did not reach 400 in testing. These were the spikes during testing.
The bulk free of 64 pointers at once should improve the give-back if the
list grows. The list size is ~1.3 items per invocations.

Having one global scf_free_pool with one cleaning thread let the list
grow to over 10.000 items with 32 CPUs (again, spikes not the average)
especially if the CPU went to sleep. The per-CPU part looks like a good
compromise.

Reported-by: "Paul E. McKenney" <[email protected]>
Closes: https://lore.kernel.org/lkml/41619255-cdc2-4573-a360-7794fc3614f7@paulmck-laptop/
Tested-by: Paul E. McKenney <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Tested-by: Boqun Feng <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Move memory allocation outside of preempt_disable region.

Memory allocations can not happen within regions with explicit disabled
preemption PREEMPT_RT. The problem is that the locking s

scftorture: Move memory allocation outside of preempt_disable region.

Memory allocations can not happen within regions with explicit disabled
preemption PREEMPT_RT. The problem is that the locking structures
underneath are sleeping locks.

Move the memory allocation outside of the preempt-disabled section. Keep
the GFP_ATOMIC for the allocation to behave like a "ememergncy
allocation".

Tested-by: Paul E. McKenney <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Tested-by: Boqun Feng <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Wait until scf_cleanup_handler() completes.

The smp_call_function() needs to be invoked with the wait flag set to
wait until scf_cleanup_handler() is done. This ensures that all SMP
func

scftorture: Wait until scf_cleanup_handler() completes.

The smp_call_function() needs to be invoked with the wait flag set to
wait until scf_cleanup_handler() is done. This ensures that all SMP
function calls, that have been queued earlier, complete at this point.

Tested-by: Paul E. McKenney <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Tested-by: Boqun Feng <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Avoid additional div operation.

Replace "scfp->cpu % nr_cpu_ids" with "cpu". This has been computed
earlier.

Tested-by: Paul E. McKenney <[email protected]>
Signed-off-by: Sebastian An

scftorture: Avoid additional div operation.

Replace "scfp->cpu % nr_cpu_ids" with "cpu". This has been computed
earlier.

Tested-by: Paul E. McKenney <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Tested-by: Boqun Feng <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Make torture_type static

Fix the 'make C=1' warning:
kernel/scftorture.c:71:6: warning: symbol 'torture_type' was not declared. Should it be static?

Signed-off-by: Jeff Johnson <quic_jj

scftorture: Make torture_type static

Fix the 'make C=1' warning:
kernel/scftorture.c:71:6: warning: symbol 'torture_type' was not declared. Should it be static?

Signed-off-by: Jeff Johnson <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Add MODULE_DESCRIPTION()

Fix the 'make W=1' warning:
WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/scftorture.o

Signed-off-by: Jeff Johnson <[email protected]>
Signed

scftorture: Add MODULE_DESCRIPTION()

Fix the 'make W=1' warning:
WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/scftorture.o

Signed-off-by: Jeff Johnson <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Pause testing after memory-allocation failure

The scftorture test can quickly execute a large number of calls to no-wait
smp_call_function(), each of which holds a block of memory until

scftorture: Pause testing after memory-allocation failure

The scftorture test can quickly execute a large number of calls to no-wait
smp_call_function(), each of which holds a block of memory until the
corresponding handler is invoked. Especially when the longwait module
parameter is specified, this can chew up an arbitrarily large amount
of memory. This commit therefore blocks after each memory-allocation
failure, with the duration a function of longwait.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Forgive memory-allocation failure if KASAN

Kernels built with CONFIG_KASAN=y quarantine newly freed memory in order
to better detect use-after-free errors. However, this can exhaust mem

scftorture: Forgive memory-allocation failure if KASAN

Kernels built with CONFIG_KASAN=y quarantine newly freed memory in order
to better detect use-after-free errors. However, this can exhaust memory
more quickly in allocator-heavy tests, which can result in spurious
scftorture failure. This commit therefore forgives memory-allocation
failure in kernels built with CONFIG_KASAN=y, but continues counting
the errors for use in detailed test-result analyses.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Fix distribution of short handler delays

The scftorture test module's scf_handler() function is supposed to provide
three different distributions of short delays (including "no delay") a

scftorture: Fix distribution of short handler delays

The scftorture test module's scf_handler() function is supposed to provide
three different distributions of short delays (including "no delay") and
one distribution of long delays, if specified by the scftorture.longwait
module parameter. However, the second of the two non-zero-wait short delays
is disabled due to the first such delay's "goto out" not being enclosed in
the "then" clause with the "udelay()".

This commit therefore adjusts the code to provide the intended set of
delays.

Fixes: e9d338a0b179 ("scftorture: Add smp_call_function() torture test")
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Always log error message

Unconditionally log messages corresponding to errors.

Acked-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Li Zhijian <[email protected]>
Signed-off-by

scftorture: Always log error message

Unconditionally log messages corresponding to errors.

Acked-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Li Zhijian <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Remove unused SCFTORTOUT

There are no longer any users of SCFTORTOUT(), so this commit removes it.

Acked-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Li Zhijian <zhijianx.li@inte

scftorture: Remove unused SCFTORTOUT

There are no longer any users of SCFTORTOUT(), so this commit removes it.

Acked-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Li Zhijian <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Add missing '\n' to flush message

Add '\n' to macros to flush message for each call.

Acked-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Li Zhijian <[email protected]>
Signed-

scftorture: Add missing '\n' to flush message

Add '\n' to macros to flush message for each call.

Acked-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Li Zhijian <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Warn on individual scf_torture_init() error conditions

When running scftorture as a module, any scf_torture_init() issues will be
reflected in the error code from modprobe or insmod, as

scftorture: Warn on individual scf_torture_init() error conditions

When running scftorture as a module, any scf_torture_init() issues will be
reflected in the error code from modprobe or insmod, as the case may be.
However, these error codes are not available when running scftorture
built-in, for example, when using the kvm.sh script. This commit
therefore adds WARN_ON_ONCE() to allow distinguishing scf_torture_init()
errors when running scftorture built-in.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Count reschedule IPIs

Currently, only those IPIs that invoke scftorture's scf_handler()
IPI handler function are counted. This means that runs exercising
only scftorture.weight_resched

scftorture: Count reschedule IPIs

Currently, only those IPIs that invoke scftorture's scf_handler()
IPI handler function are counted. This means that runs exercising
only scftorture.weight_resched will look like they have made no forward
progress, resulting in "GP HANG" complaints from the rcutorture scripting.
This commit therefore increments the scf_invoked_count per-CPU counter
immediately after calling resched_cpu().

Fixes: 1ac78b49d61d4 ("scftorture: Add an alternative IPI vector")
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Account for weight_resched when checking for all zeroes

The "all zero weights makes no sense" error is emitted even when
scftorture.weight_resched is non-zero because it was left out of

scftorture: Account for weight_resched when checking for all zeroes

The "all zero weights makes no sense" error is emitted even when
scftorture.weight_resched is non-zero because it was left out of
the enclosing "if" condition. This commit adds it in.

Fixes: 1ac78b49d61d4 ("scftorture: Add an alternative IPI vector")
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Shut down if nonsensical arguments given

If (say) a 10-hour scftorture run is started, but the module parameters
are so nonsensical that the run doesn't even start, then scftorture will

scftorture: Shut down if nonsensical arguments given

If (say) a 10-hour scftorture run is started, but the module parameters
are so nonsensical that the run doesn't even start, then scftorture will
wait the full ten hours when run built into a guest OS. This commit
therefore shuts down the system in this case so that the error is reported
immediately instead of ten hours hence.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Allow zero weight to exclude an smp_call_function*() category

This commit reworks the weighting calculations to allow zero to
be specified to disable a given weight. For example, specif

scftorture: Allow zero weight to exclude an smp_call_function*() category

This commit reworks the weighting calculations to allow zero to
be specified to disable a given weight. For example, specifying the
scftorture.weight_resched=0 kernel boot parameter without specifying a
non-zero value for any of the other scftorture.weight_* parameters would
provide the default weights for the others, but would refrain from doing
any resched-based IPIs.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Avoid NULL pointer exception on early exit

When scftorture finds an error in the module parameters controlling
the relative frequencies of smp_call_function*() variants, it takes an
earl

scftorture: Avoid NULL pointer exception on early exit

When scftorture finds an error in the module parameters controlling
the relative frequencies of smp_call_function*() variants, it takes an
early exit. So early that it has not allocated memory to track the
kthreads running the test, which results in a segfault. This commit
therefore checks for the existence of the memory before attempting
to stop the kthreads that would otherwise have been recorded in that
non-existent memory.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Add RPC-like IPI tests

This commit adds the single_weight_rpc module parameter, which causes the
IPI handler to awaken the IPI sender. In many scheduler configurations,
this will result

scftorture: Add RPC-like IPI tests

This commit adds the single_weight_rpc module parameter, which causes the
IPI handler to awaken the IPI sender. In many scheduler configurations,
this will result in an IPI back to the sender that is likely to be
received at a time when the sender CPU is idle. The intent is to stress
IPI reception during CPU busy-to-idle transitions.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Avoid false-positive warnings in scftorture_invoker()

If the call to set_cpus_allowed_ptr() in scftorture_invoker()
fails, a later WARN_ONCE() complains. But with the advent of
570a752b

scftorture: Avoid false-positive warnings in scftorture_invoker()

If the call to set_cpus_allowed_ptr() in scftorture_invoker()
fails, a later WARN_ONCE() complains. But with the advent of
570a752b7a9b ("lib/smp_processor_id: Use is_percpu_thread() instead of
nr_cpus_allowed"), this complaint can be drowned out by complaints from
smp_processor_id(). The rationale for this change is that scftorture's
kthreads are not marked with PF_NO_SETAFFINITY, which means that a system
administrator could change affinity at any time.

However, scftorture is a torture test, and the system administrator might
well have a valid test-the-test reason for changing affinity. This commit
therefore changes to raw_smp_processor_id() in order to avoid the noise,
and also adds a WARN_ON_ONCE() to the call to set_cpus_allowed_ptr() in
order to directly detect immediate failure. There is no WARN_ON_ONCE()
within the test loop, allowing human-reflex-based affinity resetting,
if desired.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Add debug output for wrong-CPU warning

This commit adds the desired CPU, the actual CPU, and nr_cpu_ids to
the wrong-CPU warning in scftorture_invoker(), the better to help with
debuggin

scftorture: Add debug output for wrong-CPU warning

This commit adds the desired CPU, the actual CPU, and nr_cpu_ids to
the wrong-CPU warning in scftorture_invoker(), the better to help with
debugging.

Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Add full-test stutter capability

In virtual environments on systems with hardware assist, inter-processor
interrupts must do very different things based on whether the target
vCPU is run

scftorture: Add full-test stutter capability

In virtual environments on systems with hardware assist, inter-processor
interrupts must do very different things based on whether the target
vCPU is running or not. This commit therefore enables torture-test
stuttering to better test these running/not-running transitions.

Suggested-by: Chris Mason <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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scftorture: Add an alternative IPI vector

The scftorture tests currently use only smp_call_function() and
friends, which means that these tests cannot locate bugs caused by
interactions between diff

scftorture: Add an alternative IPI vector

The scftorture tests currently use only smp_call_function() and
friends, which means that these tests cannot locate bugs caused by
interactions between different IPI vectors. This commit therefore adds
the rescheduling IPI to the mix.

Note that this commit permits resched_cpus() only when scftorture is
built in. This is a workaround. Longer term, this will use real wakeups
rather than resched_cpu().

Signed-off-by: Paul E. McKenney <[email protected]>

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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_fu

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 <[email protected]>

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