path: root/lib
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authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-18 14:34:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-18 14:34:50 -0700
commit41eea65e2aaadc0611fd56a1b177ce25dcc4c1df (patch)
tree75a923658e76b40792db00c79ff2f115b07b963a /lib
parent373014bb517e0bb291714fe1e232fb606d54931b (diff)
parentb36c830f8c9b13bfe69b117e879153776c19ad82 (diff)
Merge tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU changes from Ingo Molnar: - Debugging for smp_call_function() - RT raw/non-raw lock ordering fixes - Strict grace periods for KASAN - New smp_call_function() torture test - Torture-test updates - Documentation updates - Miscellaneous fixes [ This doesn't actually pull the tag - I've dropped the last merge from the RCU branch due to questions about the series. - Linus ] * tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits) smp: Make symbol 'csd_bug_count' static kernel/smp: Provide CSD lock timeout diagnostics smp: Add source and destination CPUs to __call_single_data rcu: Shrink each possible cpu krcp rcu/segcblist: Prevent useless GP start if no CBs to accelerate torture: Add gdb support rcutorture: Allow pointer leaks to test diagnostic code rcutorture: Hoist OOM registry up one level refperf: Avoid null pointer dereference when buf fails to allocate rcutorture: Properly synchronize with OOM notifier rcutorture: Properly set rcu_fwds for OOM handling torture: Add kvm.sh --help and update help message rcutorture: Add CONFIG_PROVE_RCU_LIST to TREE05 torture: Update initrd documentation rcutorture: Replace HTTP links with HTTPS ones locktorture: Make function torture_percpu_rwsem_init() static torture: document --allcpus argument added to the kvm.sh script rcutorture: Output number of elapsed grace periods rcutorture: Remove KCSAN stubs rcu: Remove unused "cpu" parameter from rcu_report_qs_rdp() ...
Diffstat (limited to 'lib')
2 files changed, 26 insertions, 1 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ebe5ab111e65..279926f5f843 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1367,6 +1367,27 @@ config WW_MUTEX_SELFTEST
Say M if you want these self tests to build as a module.
Say N if you are unsure.
+ tristate "torture tests for smp_call_function*()"
+ depends on DEBUG_KERNEL
+ help
+ This option provides a kernel module that runs torture tests
+ on the smp_call_function() family of primitives. The kernel
+ module may be built after the fact on the running kernel to
+ be tested, if desired.
+ bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
+ depends on DEBUG_KERNEL
+ depends on 64BIT
+ default n
+ help
+ This option enables debug prints when CPUs are slow to respond
+ to the smp_call_function*() IPI wrappers. These debug prints
+ include the IPI handler function currently executing (if any)
+ and relevant stack traces.
endmenu # lock debugging
diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 15ca78e1c7d4..8abe1870dba4 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -85,12 +85,16 @@ void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
+// Dump stacks even for idle CPUs.
+static bool backtrace_idle;
+module_param(backtrace_idle, bool, 0644);
bool nmi_cpu_backtrace(struct pt_regs *regs)
int cpu = smp_processor_id();
if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
- if (regs && cpu_in_idle(instruction_pointer(regs))) {
+ if (!READ_ONCE(backtrace_idle) && regs && cpu_in_idle(instruction_pointer(regs))) {
pr_warn("NMI backtrace for cpu %d skipped: idling at %pS\n",
cpu, (void *)instruction_pointer(regs));
} else {

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