This is a note to let you know that I've just added the patch titled
nmi_backtrace: allow excluding an arbitrary CPU
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nmi_backtrace-allow-excluding-an-arbitrary-cpu.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5b9dfc351a2ef79809974f4b28e60c8bc54579f8
Author: Douglas Anderson <dianders@xxxxxxxxxxxx>
Date: Fri Aug 4 07:00:42 2023 -0700
nmi_backtrace: allow excluding an arbitrary CPU
[ Upstream commit 8d539b84f1e3478436f978ceaf55a0b6cab497b5 ]
The APIs that allow backtracing across CPUs have always had a way to
exclude the current CPU. This convenience means callers didn't need to
find a place to allocate a CPU mask just to handle the common case.
Let's extend the API to take a CPU ID to exclude instead of just a
boolean. This isn't any more complex for the API to handle and allows the
hardlockup detector to exclude a different CPU (the one it already did a
trace for) without needing to find space for a CPU mask.
Arguably, this new API also encourages safer behavior. Specifically if
the caller wants to avoid tracing the current CPU (maybe because they
already traced the current CPU) this makes it more obvious to the caller
that they need to make sure that the current CPU ID can't change.
[akpm@xxxxxxxxxxxxxxxxxxxx: fix trigger_allbutcpu_cpu_backtrace() stub]
Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Cc: Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Pingfan Liu <kernelfans@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Stable-dep-of: 1f38c86bb29f ("watchdog/hardlockup: avoid large stack frames in watchdog_hardlockup_check()")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
index 18605f1b35807..26c1d2ced4ce1 100644
--- a/arch/arm/include/asm/irq.h
+++ b/arch/arm/include/asm/irq.h
@@ -32,7 +32,7 @@ void handle_IRQ(unsigned int, struct pt_regs *);
#include <linux/cpumask.h>
extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
- bool exclude_self);
+ int exclude_cpu);
#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
#endif
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 6756203e45f3d..3431c0553f45c 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -846,7 +846,7 @@ static void raise_nmi(cpumask_t *mask)
__ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
}
-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
- nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
+ nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_nmi);
}
diff --git a/arch/loongarch/include/asm/irq.h b/arch/loongarch/include/asm/irq.h
index a115e8999c69e..218b4da0ea90d 100644
--- a/arch/loongarch/include/asm/irq.h
+++ b/arch/loongarch/include/asm/irq.h
@@ -40,7 +40,7 @@ void spurious_interrupt(void);
#define NR_IRQS_LEGACY 16
#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
-void arch_trigger_cpumask_backtrace(const struct cpumask *mask, bool exclude_self);
+void arch_trigger_cpumask_backtrace(const struct cpumask *mask, int exclude_cpu);
#define MAX_IO_PICS 2
#define NR_IRQS (64 + (256 * MAX_IO_PICS))
diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
index 4ee1e9d6a65f1..ba457e43f5be5 100644
--- a/arch/loongarch/kernel/process.c
+++ b/arch/loongarch/kernel/process.c
@@ -338,9 +338,9 @@ static void raise_backtrace(cpumask_t *mask)
}
}
-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
- nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
+ nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace);
}
#ifdef CONFIG_64BIT
diff --git a/arch/mips/include/asm/irq.h b/arch/mips/include/asm/irq.h
index 75abfa834ab7a..3a848e7e69f71 100644
--- a/arch/mips/include/asm/irq.h
+++ b/arch/mips/include/asm/irq.h
@@ -77,7 +77,7 @@ extern int cp0_fdc_irq;
extern int get_c0_fdc_int(void);
void arch_trigger_cpumask_backtrace(const struct cpumask *mask,
- bool exclude_self);
+ int exclude_cpu);
#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
#endif /* _ASM_IRQ_H */
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index a3225912c862d..5387ed0a51862 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -750,9 +750,9 @@ static void raise_backtrace(cpumask_t *mask)
}
}
-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
- nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
+ nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace);
}
int mips_get_process_fp_mode(struct task_struct *task)
diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h
index f257cacb49a9c..ba1a5974e7143 100644
--- a/arch/powerpc/include/asm/irq.h
+++ b/arch/powerpc/include/asm/irq.h
@@ -55,7 +55,7 @@ int irq_choose_cpu(const struct cpumask *mask);
#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI)
extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
- bool exclude_self);
+ int exclude_cpu);
#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
#endif
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
index 5de8597eaab8d..b15f15dcacb5c 100644
--- a/arch/powerpc/kernel/stacktrace.c
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -221,8 +221,8 @@ static void raise_backtrace_ipi(cpumask_t *mask)
}
}
-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
- nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi);
+ nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace_ipi);
}
#endif /* defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI) */
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index edb2dd1f53ebc..8c464a5d82469 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -245,7 +245,7 @@ static void watchdog_smp_panic(int cpu)
__cpumask_clear_cpu(c, &wd_smp_cpus_ipi);
}
} else {
- trigger_allbutself_cpu_backtrace();
+ trigger_allbutcpu_cpu_backtrace(cpu);
cpumask_clear(&wd_smp_cpus_ipi);
}
@@ -416,7 +416,7 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt)
xchg(&__wd_nmi_output, 1); // see wd_lockup_ipi
if (sysctl_hardlockup_all_cpu_backtrace)
- trigger_allbutself_cpu_backtrace();
+ trigger_allbutcpu_cpu_backtrace(cpu);
if (hardlockup_panic)
nmi_panic(regs, "Hard LOCKUP");
diff --git a/arch/sparc/include/asm/irq_64.h b/arch/sparc/include/asm/irq_64.h
index b436029f1ced2..8c4c0c87f9980 100644
--- a/arch/sparc/include/asm/irq_64.h
+++ b/arch/sparc/include/asm/irq_64.h
@@ -87,7 +87,7 @@ static inline unsigned long get_softint(void)
}
void arch_trigger_cpumask_backtrace(const struct cpumask *mask,
- bool exclude_self);
+ int exclude_cpu);
#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
extern void *hardirq_stack[NR_CPUS];
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index b51d8fb0ecdc2..1ea3f37fa9851 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -236,7 +236,7 @@ static void __global_reg_poll(struct global_reg_snapshot *gp)
}
}
-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
struct thread_info *tp = current_thread_info();
struct pt_regs *regs = get_irq_regs();
@@ -252,7 +252,7 @@ void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
- if (cpumask_test_cpu(this_cpu, mask) && !exclude_self)
+ if (cpumask_test_cpu(this_cpu, mask) && this_cpu != exclude_cpu)
__global_reg_self(tp, regs, this_cpu);
smp_fetch_global_regs();
@@ -260,7 +260,7 @@ void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
for_each_cpu(cpu, mask) {
struct global_reg_snapshot *gp;
- if (exclude_self && cpu == this_cpu)
+ if (cpu == exclude_cpu)
continue;
gp = &global_cpu_snapshot[cpu].reg;
diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
index 29e083b92813c..836c170d30875 100644
--- a/arch/x86/include/asm/irq.h
+++ b/arch/x86/include/asm/irq.h
@@ -42,7 +42,7 @@ extern void init_ISA_irqs(void);
#ifdef CONFIG_X86_LOCAL_APIC
void arch_trigger_cpumask_backtrace(const struct cpumask *mask,
- bool exclude_self);
+ int exclude_cpu);
#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
#endif
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 34a992e275ef4..d6e01f9242996 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -34,9 +34,9 @@ static void nmi_raise_cpu_backtrace(cpumask_t *mask)
apic->send_IPI_mask(mask, NMI_VECTOR);
}
-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
- nmi_trigger_cpumask_backtrace(mask, exclude_self,
+ nmi_trigger_cpumask_backtrace(mask, exclude_cpu,
nmi_raise_cpu_backtrace);
}
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index e3e6a64b98e09..e92e378df000f 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -157,31 +157,31 @@ static inline void touch_nmi_watchdog(void)
#ifdef arch_trigger_cpumask_backtrace
static inline bool trigger_all_cpu_backtrace(void)
{
- arch_trigger_cpumask_backtrace(cpu_online_mask, false);
+ arch_trigger_cpumask_backtrace(cpu_online_mask, -1);
return true;
}
-static inline bool trigger_allbutself_cpu_backtrace(void)
+static inline bool trigger_allbutcpu_cpu_backtrace(int exclude_cpu)
{
- arch_trigger_cpumask_backtrace(cpu_online_mask, true);
+ arch_trigger_cpumask_backtrace(cpu_online_mask, exclude_cpu);
return true;
}
static inline bool trigger_cpumask_backtrace(struct cpumask *mask)
{
- arch_trigger_cpumask_backtrace(mask, false);
+ arch_trigger_cpumask_backtrace(mask, -1);
return true;
}
static inline bool trigger_single_cpu_backtrace(int cpu)
{
- arch_trigger_cpumask_backtrace(cpumask_of(cpu), false);
+ arch_trigger_cpumask_backtrace(cpumask_of(cpu), -1);
return true;
}
/* generic implementation */
void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
- bool exclude_self,
+ int exclude_cpu,
void (*raise)(cpumask_t *mask));
bool nmi_cpu_backtrace(struct pt_regs *regs);
@@ -190,7 +190,7 @@ static inline bool trigger_all_cpu_backtrace(void)
{
return false;
}
-static inline bool trigger_allbutself_cpu_backtrace(void)
+static inline bool trigger_allbutcpu_cpu_backtrace(int exclude_cpu)
{
return false;
}
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index be38276a365f3..085d7a78f62f0 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -523,7 +523,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
dump_stack();
if (softlockup_all_cpu_backtrace) {
- trigger_allbutself_cpu_backtrace();
+ trigger_allbutcpu_cpu_backtrace(smp_processor_id());
clear_bit_unlock(0, &soft_lockup_nmi_warn);
}
diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 5274bbb026d79..33c154264bfe2 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -34,7 +34,7 @@ static unsigned long backtrace_flag;
* they are passed being updated as a side effect of this call.
*/
void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
- bool exclude_self,
+ int exclude_cpu,
void (*raise)(cpumask_t *mask))
{
int i, this_cpu = get_cpu();
@@ -49,8 +49,8 @@ void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
}
cpumask_copy(to_cpumask(backtrace_mask), mask);
- if (exclude_self)
- cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
+ if (exclude_cpu != -1)
+ cpumask_clear_cpu(exclude_cpu, to_cpumask(backtrace_mask));
/*
* Don't try to send an NMI to this cpu; it may work on some
