forked from Minki/linux
8cbd0e38a9
People running automated tests have asked for a way to make RCU minimize grace-period duration in order to increase the probability of KASAN detecting a pointer being improperly leaked from an RCU read-side critical section, for example, like this: rcu_read_lock(); p = rcu_dereference(gp); do_something_with(p); // OK rcu_read_unlock(); do_something_else_with(p); // BUG!!! The rcupdate.rcu_expedited boot parameter is a start in this direction, given that it makes calls to synchronize_rcu() instead invoke the faster (and more wasteful) synchronize_rcu_expedited(). However, this does nothing to shorten RCU grace periods that are instead initiated by call_rcu(), and RCU pointer-leak bugs can involve call_rcu() just as surely as they can synchronize_rcu(). This commit therefore adds a RCU_STRICT_GRACE_PERIOD Kconfig option that will be used to shorten normal (non-expedited) RCU grace periods. This commit also dumps out a message when this option is in effect. Later commits will actually shorten grace periods. Reported-by Jann Horn <jannh@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
133 lines
4.0 KiB
Plaintext
133 lines
4.0 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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#
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# RCU-related debugging configuration options
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#
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menu "RCU Debugging"
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config PROVE_RCU
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def_bool PROVE_LOCKING
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config PROVE_RCU_LIST
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bool "RCU list lockdep debugging"
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depends on PROVE_RCU && RCU_EXPERT
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default n
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help
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Enable RCU lockdep checking for list usages. By default it is
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turned off since there are several list RCU users that still
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need to be converted to pass a lockdep expression. To prevent
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false-positive splats, we keep it default disabled but once all
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users are converted, we can remove this config option.
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config TORTURE_TEST
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tristate
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default n
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config RCU_PERF_TEST
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tristate "performance tests for RCU"
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depends on DEBUG_KERNEL
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select TORTURE_TEST
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select SRCU
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select TASKS_RCU
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select TASKS_RUDE_RCU
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select TASKS_TRACE_RCU
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default n
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help
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This option provides a kernel module that runs performance
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tests on the RCU infrastructure. The kernel module may be built
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after the fact on the running kernel to be tested, if desired.
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Say Y here if you want RCU performance tests to be built into
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the kernel.
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Say M if you want the RCU performance tests to build as a module.
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Say N if you are unsure.
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config RCU_TORTURE_TEST
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tristate "torture tests for RCU"
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depends on DEBUG_KERNEL
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select TORTURE_TEST
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select SRCU
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select TASKS_RCU
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select TASKS_RUDE_RCU
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select TASKS_TRACE_RCU
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default n
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help
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This option provides a kernel module that runs torture tests
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on the RCU infrastructure. The kernel module may be built
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after the fact on the running kernel to be tested, if desired.
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Say Y here if you want RCU torture tests to be built into
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the kernel.
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Say M if you want the RCU torture tests to build as a module.
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Say N if you are unsure.
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config RCU_REF_SCALE_TEST
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tristate "Scalability tests for read-side synchronization (RCU and others)"
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depends on DEBUG_KERNEL
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select TORTURE_TEST
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select SRCU
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select TASKS_RCU
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select TASKS_RUDE_RCU
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select TASKS_TRACE_RCU
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default n
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help
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This option provides a kernel module that runs performance tests
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useful comparing RCU with various read-side synchronization mechanisms.
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The kernel module may be built after the fact on the running kernel to be
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tested, if desired.
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Say Y here if you want these performance tests built into the kernel.
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Say M if you want to build it as a module instead.
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Say N if you are unsure.
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config RCU_CPU_STALL_TIMEOUT
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int "RCU CPU stall timeout in seconds"
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depends on RCU_STALL_COMMON
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range 3 300
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default 21
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help
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If a given RCU grace period extends more than the specified
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number of seconds, a CPU stall warning is printed. If the
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RCU grace period persists, additional CPU stall warnings are
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printed at more widely spaced intervals.
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config RCU_TRACE
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bool "Enable tracing for RCU"
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depends on DEBUG_KERNEL
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default y if TREE_RCU
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select TRACE_CLOCK
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help
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This option enables additional tracepoints for ftrace-style
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event tracing.
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Say Y here if you want to enable RCU tracing
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Say N if you are unsure.
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config RCU_EQS_DEBUG
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bool "Provide debugging asserts for adding NO_HZ support to an arch"
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depends on DEBUG_KERNEL
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help
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This option provides consistency checks in RCU's handling of
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NO_HZ. These checks have proven quite helpful in detecting
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bugs in arch-specific NO_HZ code.
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Say N here if you need ultimate kernel/user switch latencies
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Say Y if you are unsure
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config RCU_STRICT_GRACE_PERIOD
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bool "Provide debug RCU implementation with short grace periods"
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depends on DEBUG_KERNEL && RCU_EXPERT
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default n
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select PREEMPT_COUNT if PREEMPT=n
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help
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Select this option to build an RCU variant that is strict about
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grace periods, making them as short as it can. This limits
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scalability, destroys real-time response, degrades battery
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lifetime and kills performance. Don't try this on large
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machines, as in systems with more than about 10 or 20 CPUs.
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But in conjunction with tools like KASAN, it can be helpful
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when looking for certain types of RCU usage bugs, for example,
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too-short RCU read-side critical sections.
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endmenu # "RCU Debugging"
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