user/sven/linux.git/include/linux/nmi.h, branch v4.10.3

kernel/watchdog: prevent false hardlockup on overloaded system

2017-01-25T00:26:14Z

On an overloaded system, it is possible that a change in the watchdog threshold can be delayed long enough to trigger a false positive. This can easily be achieved by having a cpu spinning indefinitely on a task, while another cpu updates watchdog threshold. What happens is while trying to park the watchdog threads, the hrtimers on the other cpus trigger and reprogram themselves with the new slower watchdog threshold. Meanwhile, the nmi watchdog is still programmed with the old faster threshold. Because the one cpu is blocked, it prevents the thread parking on the other cpus from completing, which is needed to shutdown the nmi watchdog and reprogram it correctly. As a result, a false positive from the nmi watchdog is reported. Fix this by setting a park_in_progress flag to block all lockups until the parking is complete. Fix provided by Ulrich Obergfell. [akpm@linux-foundation.org: s/park_in_progress/watchdog_park_in_progress/] Link: http://lkml.kernel.org/r/1481041033-192236-1-git-send-email-dzickus@redhat.com Signed-off-by: Don Zickus Reviewed-by: Aaron Tomlin Cc: Ulrich Obergfell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/watchdog.c: move shared definitions to nmi.h

2016-12-15T00:04:08Z

Patch series "Clean up watchdog handlers", v2. This is an attempt to cleanup watchdog handlers. Right now, kernel/watchdog.c implements both softlockup and hardlockup detectors. Softlockup code is generic. Hardlockup code is arch specific. Some architectures don't use hardlockup detectors. They use their own watchdog detectors. To make both these combination work, we have numerous #ifdefs in kernel/watchdog.c. We are trying here to make these handlers independent of each other. Also provide an interface for architectures to implement their own handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined as weak such that architectures can override its definitions. Thanks to Don Zickus for his suggestions. Here are our previous discussions http://www.spinics.net/lists/sparclinux/msg16543.html http://www.spinics.net/lists/sparclinux/msg16441.html This patch (of 3): Move shared macros and definitions to nmi.h so that watchdog.c, new file watchdog_hld.c or any other architecture specific handler can use those definitions. Link: http://lkml.kernel.org/r/1478034826-43888-2-git-send-email-babu.moger@oracle.com Signed-off-by: Babu Moger Acked-by: Don Zickus Cc: Ingo Molnar Cc: Jiri Kosina Cc: Andi Kleen Cc: Yaowei Bai Cc: Aaron Tomlin Cc: Ulrich Obergfell Cc: Tejun Heo Cc: Hidehiro Kawai Cc: Josh Hunt Cc: "David S. Miller" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

nmi_backtrace: add more trigger_*_cpu_backtrace() methods

2016-10-08T01:46:30Z

Patch series "improvements to the nmi_backtrace code" v9. This patch series modifies the trigger_xxx_backtrace() NMI-based remote backtracing code to make it more flexible, and makes a few small improvements along the way. The motivation comes from the task isolation code, where there are scenarios where we want to be able to diagnose a case where some cpu is about to interrupt a task-isolated cpu. It can be helpful to see both where the interrupting cpu is, and also an approximation of where the cpu that is being interrupted is. The nmi_backtrace framework allows us to discover the stack of the interrupted cpu. I've tested that the change works as desired on tile, and build-tested x86, arm, mips, and sparc64. For x86 I confirmed that the generic cpuidle stuff as well as the architecture-specific routines are in the new cpuidle section. For arm, mips, and sparc I just build-tested it and made sure the generic cpuidle routines were in the new cpuidle section, but I didn't attempt to figure out which the platform-specific idle routines might be. That might be more usefully done by someone with platform experience in follow-up patches. This patch (of 4): Currently you can only request a backtrace of either all cpus, or all cpus but yourself. It can also be helpful to request a remote backtrace of a single cpu, and since we want that, the logical extension is to support a cpumask as the underlying primitive. This change modifies the existing lib/nmi_backtrace.c code to take a cpumask as its basic primitive, and modifies the linux/nmi.h code to use the new "cpumask" method instead. The existing clients of nmi_backtrace (arm and x86) are converted to using the new cpumask approach in this change. The other users of the backtracing API (sparc64 and mips) are converted to use the cpumask approach rather than the all/allbutself approach. The mips code ignored the "include_self" boolean but with this change it will now also dump a local backtrace if requested. Link: http://lkml.kernel.org/r/1472487169-14923-2-git-send-email-cmetcalf@mellanox.com Signed-off-by: Chris Metcalf Tested-by: Daniel Thompson [arm] Reviewed-by: Aaron Tomlin Reviewed-by: Petr Mladek Cc: "Rafael J. Wysocki" Cc: Russell King Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Ralf Baechle Cc: David Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

x86/apic: Remove declaration of unused hw_nmi_is_cpu_stuck

2016-03-23T11:34:17Z

Commit 10f9014912 ("x86: Cleanup hw_nmi.c cruft") removed unused code in the hw_nmi.c file because of the redesign of the hardlockup watchdog but left declaration of hw_nmi_is_cpu_stuck in linux/nmi.h, so remvoe it. Signed-off-by: Yaowei Bai Link: http://lkml.kernel.org/r/1458697210-3027-1-git-send-email-baiyaowei@cmss.chinamobile.com Signed-off-by: Thomas Gleixner

kernel/watchdog.c: perform all-CPU backtrace in case of hard lockup

2015-11-06T03:34:48Z

In many cases of hardlockup reports, it's actually not possible to know why it triggered, because the CPU that got stuck is usually waiting on a resource (with IRQs disabled) in posession of some other CPU is holding. IOW, we are often looking at the stacktrace of the victim and not the actual offender. Introduce sysctl / cmdline parameter that makes it possible to have hardlockup detector perform all-CPU backtrace. Signed-off-by: Jiri Kosina Reviewed-by: Aaron Tomlin Cc: Ulrich Obergfell Acked-by: Don Zickus Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'nmi' of git://ftp.arm.linux.org.uk/~rmk/linux-arm

2015-09-08T19:28:10Z

Pull NMI backtrace update from Russell King: "These changes convert the x86 NMI handling to be a library implementation which other architectures can make use of. Thomas Gleixner has reviewed and tested these changes, and wishes me to send these rather than taking them through the tip tree. The final patch in the set adds an initial implementation using this infrastructure to ARM, even though it doesn't send the IPI at "NMI" level. Patches are in progress to add the ARM equivalent of NMI, but we still need the IRQ-level fallback for systems where the "NMI" isn't available due to secure firmware denying access to it" * 'nmi' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: ARM: add basic support for on-demand backtrace of other CPUs nmi: x86: convert to generic nmi handler nmi: create generic NMI backtrace implementation

watchdog: rename watchdog_suspend() and watchdog_resume()

2015-09-04T23:54:41Z

Rename watchdog_suspend() to lockup_detector_suspend() and watchdog_resume() to lockup_detector_resume() to avoid confusion with the watchdog subsystem and to be consistent with the existing name lockup_detector_init(). Also provide comment blocks to explain the watchdog_running and watchdog_suspended variables and their relationship. Signed-off-by: Ulrich Obergfell Reviewed-by: Aaron Tomlin Cc: Guenter Roeck Cc: Don Zickus Cc: Ulrich Obergfell Cc: Jiri Olsa Cc: Michal Hocko Cc: Stephane Eranian Cc: Chris Metcalf Cc: Frederic Weisbecker Cc: Peter Zijlstra Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

watchdog: use suspend/resume interface in fixup_ht_bug()

2015-09-04T23:54:41Z

Remove watchdog_nmi_disable_all() and watchdog_nmi_enable_all() since these functions are no longer needed. If a subsystem has a need to deactivate the watchdog temporarily, it should utilize the watchdog_suspend() and watchdog_resume() functions. [akpm@linux-foundation.org: fix build with CONFIG_LOCKUP_DETECTOR=m] Signed-off-by: Ulrich Obergfell Reviewed-by: Aaron Tomlin Cc: Guenter Roeck Cc: Don Zickus Cc: Ulrich Obergfell Cc: Jiri Olsa Cc: Michal Hocko Cc: Stephane Eranian Cc: Chris Metcalf Cc: Frederic Weisbecker Cc: Peter Zijlstra Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

watchdog: introduce watchdog_suspend() and watchdog_resume()

2015-09-04T23:54:41Z

This interface can be utilized to deactivate the hard and soft lockup detector temporarily. Callers are expected to minimize the duration of deactivation. Multiple deactivations are allowed to occur in parallel but should be rare in practice. [akpm@linux-foundation.org: remove unneeded static initialization] Signed-off-by: Ulrich Obergfell Reviewed-by: Aaron Tomlin Cc: Guenter Roeck Cc: Don Zickus Cc: Ulrich Obergfell Cc: Jiri Olsa Cc: Michal Hocko Cc: Stephane Eranian Cc: Chris Metcalf Cc: Frederic Weisbecker Cc: Peter Zijlstra Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/watchdog: move NMI function header declarations from watchdog.h to nmi.h

2015-09-04T23:54:41Z

The kernel's NMI watchdog has nothing to do with the watchdog subsystem. Its header declarations should be in linux/nmi.h, not linux/watchdog.h. The code provided two sets of dummy functions if HARDLOCKUP_DETECTOR is not configured, one in the include file and one in kernel/watchdog.c. Remove the dummy functions from kernel/watchdog.c and use those from the include file. Signed-off-by: Guenter Roeck Cc: Stephane Eranian Cc: Peter Zijlstra (Intel) Cc: Ingo Molnar Cc: Don Zickus Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds