[GIT PULL] debugging updates

From: Ingo Molnar
Date: Fri Jan 31 2014 - 03:15:53 EST

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Linus,

Please pull the latest core-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-urgent-for-linus

# HEAD: 270750dbc18a71b23d660df110e433ff9616a2d4 hung_task: Display every hung task warning

It contains mostly kernel debugging related updates:

- make hung_task detection more configurable to distros
- add final bits for x86 UV NMI debugging, with related KGDB changes
- update the mailing-list of MAINTAINERS entries I'm involved with

Thanks,

Ingo

------------------>
Aaron Tomlin (2):
sysctl: Add neg_one as a standard constraint
hung_task: Display every hung task warning

Ingo Molnar (1):
MAINTAINERS: Restore "L: linux-kernel@xxxxxxxxxxxxxxx" entries

Mike Travis (3):
kgdb/kdb: Fix no KDB config problem
x86/uv/nmi: Fix Sparse warnings
x86/uv/nmi, kgdb/kdb: Fix UV NMI handler when KDB not configured

Documentation/sysctl/kernel.txt | 42 ++++++++++++++++++++++++
MAINTAINERS | 13 ++++++++
arch/x86/include/asm/uv/uv.h | 2 --
arch/x86/kernel/apic/x2apic_uv_x.c | 1 -
arch/x86/platform/uv/uv_nmi.c | 65 +++++++++++++++++++++++++++-----------
include/linux/kgdb.h | 3 +-
include/linux/sched/sysctl.h | 2 +-
kernel/debug/debug_core.c | 5 +--
kernel/debug/debug_core.h | 2 --
kernel/hung_task.c | 6 ++--
kernel/sysctl.c | 7 ++--
11 files changed, 116 insertions(+), 32 deletions(-)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 6d48640..4205f3c 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -33,6 +33,10 @@ show up in /proc/sys/kernel:
- domainname
- hostname
- hotplug
+- hung_task_panic
+- hung_task_check_count
+- hung_task_timeout_secs
+- hung_task_warnings
- kptr_restrict
- kstack_depth_to_print [ X86 only ]
- l2cr [ PPC only ]
@@ -287,6 +291,44 @@ Default value is "/sbin/hotplug".

==============================================================

+hung_task_panic:
+
+Controls the kernel's behavior when a hung task is detected.
+This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
+
+0: continue operation. This is the default behavior.
+
+1: panic immediately.
+
+==============================================================
+
+hung_task_check_count:
+
+The upper bound on the number of tasks that are checked.
+This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
+
+==============================================================
+
+hung_task_timeout_secs:
+
+Check interval. When a task in D state did not get scheduled
+for more than this value report a warning.
+This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
+
+0: means infinite timeout - no checking done.
+
+==============================================================
+
+hung_task_warning:
+
+The maximum number of warnings to report. During a check interval
+When this value is reached, no more the warnings will be reported.
+This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
+
+-1: report an infinite number of warnings.
+
+==============================================================
+
kptr_restrict:

This toggle indicates whether restrictions are placed on
diff --git a/MAINTAINERS b/MAINTAINERS
index ce1645e..e048de5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2191,6 +2191,7 @@ F: include/linux/clk.h
CLOCKSOURCE, CLOCKEVENT DRIVERS
M: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
M: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
S: Supported
F: drivers/clocksource
@@ -3985,6 +3986,7 @@ F: include/uapi/linux/hid*

HIGH-RESOLUTION TIMERS, CLOCKEVENTS, DYNTICKS
M: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
S: Maintained
F: Documentation/timers/
@@ -4654,6 +4656,7 @@ F: net/irda/

IRQ SUBSYSTEM
M: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
S: Maintained
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq/core
F: kernel/irq/
@@ -5285,6 +5288,7 @@ F: drivers/media/usb/dvb-usb-v2/lmedm04*
LOCKDEP AND LOCKSTAT
M: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
M: Ingo Molnar <mingo@xxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core/locking
S: Maintained
F: Documentation/lockdep*.txt
@@ -6581,6 +6585,7 @@ M: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
M: Paul Mackerras <paulus@xxxxxxxxx>
M: Ingo Molnar <mingo@xxxxxxxxxx>
M: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf/core
S: Supported
F: kernel/events/*
@@ -6704,6 +6709,7 @@ F: drivers/scsi/pm8001/

POSIX CLOCKS and TIMERS
M: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
S: Supported
F: fs/timerfd.c
@@ -7099,6 +7105,7 @@ F: drivers/net/wireless/ray*
RCUTORTURE MODULE
M: Josh Triplett <josh@xxxxxxxxxxxxxxx>
M: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
F: Documentation/RCU/torture.txt
@@ -7106,6 +7113,7 @@ F: kernel/rcu/torture.c

RCUTORTURE TEST FRAMEWORK
M: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
F: tools/testing/selftests/rcutorture
@@ -7129,6 +7137,7 @@ F: net/rds/
READ-COPY UPDATE (RCU)
M: Dipankar Sarma <dipankar@xxxxxxxxxx>
M: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
W: http://www.rdrop.com/users/paulmck/RCU/
S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
@@ -7432,6 +7441,7 @@ F: drivers/mmc/host/dw_mmc*
TIMEKEEPING, CLOCKSOURCE CORE, NTP
M: John Stultz <john.stultz@xxxxxxxxxx>
M: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
S: Supported
F: include/linux/clocksource.h
@@ -7457,6 +7467,7 @@ F: drivers/watchdog/sc1200wdt.c
SCHEDULER
M: Ingo Molnar <mingo@xxxxxxxxxx>
M: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core
S: Maintained
F: kernel/sched/
@@ -7823,6 +7834,7 @@ F: mm/sl?b.c
SLEEPABLE READ-COPY UPDATE (SRCU)
M: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
M: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
+L: linux-kernel@xxxxxxxxxxxxxxx
W: http://www.rdrop.com/users/paulmck/RCU/
S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
@@ -9531,6 +9543,7 @@ M: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
M: Ingo Molnar <mingo@xxxxxxxxxx>
M: "H. Peter Anvin" <hpa@xxxxxxxxx>
M: x86@xxxxxxxxxx
+L: linux-kernel@xxxxxxxxxxxxxxx
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/core
S: Maintained
F: Documentation/x86/
diff --git a/arch/x86/include/asm/uv/uv.h b/arch/x86/include/asm/uv/uv.h
index 6b964a0..062921e 100644
--- a/arch/x86/include/asm/uv/uv.h
+++ b/arch/x86/include/asm/uv/uv.h
@@ -12,7 +12,6 @@ extern enum uv_system_type get_uv_system_type(void);
extern int is_uv_system(void);
extern void uv_cpu_init(void);
extern void uv_nmi_init(void);
-extern void uv_register_nmi_notifier(void);
extern void uv_system_init(void);
extern const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
struct mm_struct *mm,
@@ -26,7 +25,6 @@ static inline enum uv_system_type get_uv_system_type(void) { return UV_NONE; }
static inline int is_uv_system(void) { return 0; }
static inline void uv_cpu_init(void) { }
static inline void uv_system_init(void) { }
-static inline void uv_register_nmi_notifier(void) { }
static inline const struct cpumask *
uv_flush_tlb_others(const struct cpumask *cpumask, struct mm_struct *mm,
unsigned long start, unsigned long end, unsigned int cpu)
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index ad0dc04..d263b13 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -980,7 +980,6 @@ void __init uv_system_init(void)
uv_nmi_setup();
uv_cpu_init();
uv_scir_register_cpu_notifier();
- uv_register_nmi_notifier();
proc_mkdir("sgi_uv", NULL);

/* register Legacy VGA I/O redirection handler */
diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
index 8eeccba..be27da6 100644
--- a/arch/x86/platform/uv/uv_nmi.c
+++ b/arch/x86/platform/uv/uv_nmi.c
@@ -74,7 +74,6 @@ static atomic_t uv_in_nmi;
static atomic_t uv_nmi_cpu = ATOMIC_INIT(-1);
static atomic_t uv_nmi_cpus_in_nmi = ATOMIC_INIT(-1);
static atomic_t uv_nmi_slave_continue;
-static atomic_t uv_nmi_kexec_failed;
static cpumask_var_t uv_nmi_cpu_mask;

/* Values for uv_nmi_slave_continue */
@@ -149,7 +148,8 @@ module_param_named(retry_count, uv_nmi_retry_count, int, 0644);
* "dump" - dump process stack for each cpu
* "ips" - dump IP info for each cpu
* "kdump" - do crash dump
- * "kdb" - enter KDB/KGDB (default)
+ * "kdb" - enter KDB (default)
+ * "kgdb" - enter KGDB
*/
static char uv_nmi_action[8] = "kdb";
module_param_string(action, uv_nmi_action, sizeof(uv_nmi_action), 0644);
@@ -504,6 +504,7 @@ static void uv_nmi_touch_watchdogs(void)
}

#if defined(CONFIG_KEXEC)
+static atomic_t uv_nmi_kexec_failed;
static void uv_nmi_kdump(int cpu, int master, struct pt_regs *regs)
{
/* Call crash to dump system state */
@@ -537,18 +538,45 @@ static inline void uv_nmi_kdump(int cpu, int master, struct pt_regs *regs)
}
#endif /* !CONFIG_KEXEC */

+#ifdef CONFIG_KGDB
#ifdef CONFIG_KGDB_KDB
-/* Call KDB from NMI handler */
-static void uv_call_kdb(int cpu, struct pt_regs *regs, int master)
+static inline int uv_nmi_kdb_reason(void)
{
- int ret;
+ return KDB_REASON_SYSTEM_NMI;
+}
+#else /* !CONFIG_KGDB_KDB */
+static inline int uv_nmi_kdb_reason(void)
+{
+ /* Insure user is expecting to attach gdb remote */
+ if (uv_nmi_action_is("kgdb"))
+ return 0;
+
+ pr_err("UV: NMI error: KDB is not enabled in this kernel\n");
+ return -1;
+}
+#endif /* CONFIG_KGDB_KDB */

+/*
+ * Call KGDB/KDB from NMI handler
+ *
+ * Note that if both KGDB and KDB are configured, then the action of 'kgdb' or
+ * 'kdb' has no affect on which is used. See the KGDB documention for further
+ * information.
+ */
+static void uv_call_kgdb_kdb(int cpu, struct pt_regs *regs, int master)
+{
if (master) {
+ int reason = uv_nmi_kdb_reason();
+ int ret;
+
+ if (reason < 0)
+ return;
+
/* call KGDB NMI handler as MASTER */
- ret = kgdb_nmicallin(cpu, X86_TRAP_NMI, regs,
- &uv_nmi_slave_continue);
+ ret = kgdb_nmicallin(cpu, X86_TRAP_NMI, regs, reason,
+ &uv_nmi_slave_continue);
if (ret) {
- pr_alert("KDB returned error, is kgdboc set?\n");
+ pr_alert("KGDB returned error, is kgdboc set?\n");
atomic_set(&uv_nmi_slave_continue, SLAVE_EXIT);
}
} else {
@@ -567,12 +595,12 @@ static void uv_call_kdb(int cpu, struct pt_regs *regs, int master)
uv_nmi_sync_exit(master);
}

-#else /* !CONFIG_KGDB_KDB */
-static inline void uv_call_kdb(int cpu, struct pt_regs *regs, int master)
+#else /* !CONFIG_KGDB */
+static inline void uv_call_kgdb_kdb(int cpu, struct pt_regs *regs, int master)
{
- pr_err("UV: NMI error: KGDB/KDB is not enabled in this kernel\n");
+ pr_err("UV: NMI error: KGDB is not enabled in this kernel\n");
}
-#endif /* !CONFIG_KGDB_KDB */
+#endif /* !CONFIG_KGDB */

/*
* UV NMI handler
@@ -606,9 +634,9 @@ int uv_handle_nmi(unsigned int reason, struct pt_regs *regs)
if (uv_nmi_action_is("ips") || uv_nmi_action_is("dump"))
uv_nmi_dump_state(cpu, regs, master);

- /* Call KDB if enabled */
- else if (uv_nmi_action_is("kdb"))
- uv_call_kdb(cpu, regs, master);
+ /* Call KGDB/KDB if enabled */
+ else if (uv_nmi_action_is("kdb") || uv_nmi_action_is("kgdb"))
+ uv_call_kgdb_kdb(cpu, regs, master);

/* Clear per_cpu "in nmi" flag */
atomic_set(&uv_cpu_nmi.state, UV_NMI_STATE_OUT);
@@ -634,7 +662,7 @@ int uv_handle_nmi(unsigned int reason, struct pt_regs *regs)
/*
* NMI handler for pulling in CPUs when perf events are grabbing our NMI
*/
-int uv_handle_nmi_ping(unsigned int reason, struct pt_regs *regs)
+static int uv_handle_nmi_ping(unsigned int reason, struct pt_regs *regs)
{
int ret;

@@ -651,7 +679,7 @@ int uv_handle_nmi_ping(unsigned int reason, struct pt_regs *regs)
return ret;
}

-void uv_register_nmi_notifier(void)
+static void uv_register_nmi_notifier(void)
{
if (register_nmi_handler(NMI_UNKNOWN, uv_handle_nmi, 0, "uv"))
pr_warn("UV: NMI handler failed to register\n");
@@ -695,6 +723,5 @@ void uv_nmi_setup(void)
uv_hub_nmi_per(cpu) = uv_hub_nmi_list[nid];
}
BUG_ON(!alloc_cpumask_var(&uv_nmi_cpu_mask, GFP_KERNEL));
+ uv_register_nmi_notifier();
}
-
-
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index dfb4f2f..6b06d37 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -310,7 +310,8 @@ extern int
kgdb_handle_exception(int ex_vector, int signo, int err_code,
struct pt_regs *regs);
extern int kgdb_nmicallback(int cpu, void *regs);
-extern int kgdb_nmicallin(int cpu, int trapnr, void *regs, atomic_t *snd_rdy);
+extern int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code,
+ atomic_t *snd_rdy);
extern void gdbstub_exit(int status);

extern int kgdb_single_step;
diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 31e0193..3a93f84 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -5,7 +5,7 @@
extern int sysctl_hung_task_check_count;
extern unsigned int sysctl_hung_task_panic;
extern unsigned long sysctl_hung_task_timeout_secs;
-extern unsigned long sysctl_hung_task_warnings;
+extern int sysctl_hung_task_warnings;
extern int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
void __user *buffer,
size_t *lenp, loff_t *ppos);
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 7d2f35e..334b398 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -736,7 +736,8 @@ int kgdb_nmicallback(int cpu, void *regs)
return 1;
}

-int kgdb_nmicallin(int cpu, int trapnr, void *regs, atomic_t *send_ready)
+int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code,
+ atomic_t *send_ready)
{
#ifdef CONFIG_SMP
if (!kgdb_io_ready(0) || !send_ready)
@@ -750,7 +751,7 @@ int kgdb_nmicallin(int cpu, int trapnr, void *regs, atomic_t *send_ready)
ks->cpu = cpu;
ks->ex_vector = trapnr;
ks->signo = SIGTRAP;
- ks->err_code = KGDB_KDB_REASON_SYSTEM_NMI;
+ ks->err_code = err_code;
ks->linux_regs = regs;
ks->send_ready = send_ready;
kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
diff --git a/kernel/debug/debug_core.h b/kernel/debug/debug_core.h
index 572aa4f..127d9bc 100644
--- a/kernel/debug/debug_core.h
+++ b/kernel/debug/debug_core.h
@@ -75,13 +75,11 @@ extern int kdb_stub(struct kgdb_state *ks);
extern int kdb_parse(const char *cmdstr);
extern int kdb_common_init_state(struct kgdb_state *ks);
extern int kdb_common_deinit_state(void);
-#define KGDB_KDB_REASON_SYSTEM_NMI KDB_REASON_SYSTEM_NMI
#else /* ! CONFIG_KGDB_KDB */
static inline int kdb_stub(struct kgdb_state *ks)
{
return DBG_PASS_EVENT;
}
-#define KGDB_KDB_REASON_SYSTEM_NMI 0
#endif /* CONFIG_KGDB_KDB */

#endif /* _DEBUG_CORE_H_ */
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 9328b80..0b9c169 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -37,7 +37,7 @@ int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
*/
unsigned long __read_mostly sysctl_hung_task_timeout_secs = CONFIG_DEFAULT_HUNG_TASK_TIMEOUT;

-unsigned long __read_mostly sysctl_hung_task_warnings = 10;
+int __read_mostly sysctl_hung_task_warnings = 10;

static int __read_mostly did_panic;

@@ -98,7 +98,9 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)

if (!sysctl_hung_task_warnings)
return;
- sysctl_hung_task_warnings--;
+
+ if (sysctl_hung_task_warnings > 0)
+ sysctl_hung_task_warnings--;

/*
* Ok, the task did not get scheduled for more than 2 minutes,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c8da99f..dd5b449 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -122,6 +122,8 @@ extern int blk_iopoll_enabled;
static int sixty = 60;
#endif

+static int __maybe_unused neg_one = -1;
+
static int zero;
static int __maybe_unused one = 1;
static int __maybe_unused two = 2;
@@ -977,9 +979,10 @@ static struct ctl_table kern_table[] = {
{
.procname = "hung_task_warnings",
.data = &sysctl_hung_task_warnings,
- .maxlen = sizeof(unsigned long),
+ .maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_doulongvec_minmax,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &neg_one,
},
#endif
#ifdef CONFIG_COMPAT
--
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