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| author | Paul E. McKenney <paulmck@kernel.org> | 2020-07-09 01:25:43 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-08-24 23:24:25 +0200 |
| commit | 160c7ba34605d9b59ee406a1b4a61b0f942b1ae9 (patch) | |
| tree | 6bb20cf2018927bc9fd28b8357a3e7d0410e06fc /lib | |
| parent | Linux 5.9-rc1 (diff) | |
| download | linux-160c7ba34605d9b59ee406a1b4a61b0f942b1ae9.tar.xz linux-160c7ba34605d9b59ee406a1b4a61b0f942b1ae9.zip | |
lib: Add backtrace_idle parameter to force backtrace of idle CPUs
Currently, the nmi_cpu_backtrace() declines to produce backtraces for
idle CPUs. This is a good choice in the common case in which problems are
caused only by non-idle CPUs. However, there are occasionally situations
in which idle CPUs are helping to cause problems. This commit therefore
adds an nmi_backtrace.backtrace_idle kernel boot parameter that causes
nmi_cpu_backtrace() to dump stacks even of idle CPUs.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <linux-doc@vger.kernel.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/nmi_backtrace.c | 6 |
1 files changed, 5 insertions, 1 deletions
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, put_cpu(); } +// 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 { |