This patch series adds the "buddy" hardlockup detector. In brief, the
buddy hardlockup detector can detect hardlockups without arch-level
support by having CPUs checkup on a "buddy" CPU periodically. All the
details are in the patch ("watchdog/hardlockup: detect hard lockups
using secondary (buddy) CPUs") and I encourage folks to reply to that
patch for general comments about this approach.Note that in v3, this was a single patch [1]. It's now exploded into a much larger series. The much larger series does a bunch of cleanup that Petr requested in response to v3 [2] [3]. This new series ends up sharing a lot more code with the perf lockup detector. It also tries to bring a little sanity to some of the naming we had. The fact that this series now touches across the whole lockup detector codebase also caused conflicts with the series trying to add a arm64 perf-based hardlockup detector. That was a bit incovenient for me since I was testing on arm64 and wanted to make sure that the perf and buddy hardlockup detectors both compiled and worked. Because of this, I've pulled the latest arm64 perf-based lockup detector patches into my series. Specifically: - Patches #1 - #3 of the arm64 perf-based lockup detector patches were generic cleanups. I added them early in my series. IMO these should just land. - Patches #4 - #6 of the arm64 perf-based lockup detector patches were less generic but still caused conflict with my series. I tacked them to the end of my series after adapting them to my changes. However, I don't really consider them part of this series and I'd be OK if the series landed without them. For use cases I'm aware of the buddy system is sufficient and I see no urgent need to land the arm64 perf hardlockup support, though I also don't have any strong objections to the patches. I will note that this patch series currently has no conflicts with the other patch series I posed recently adding support for pseudo-NMI based backtraces [5] and the two patches series are meant to work together. Given the new design of this patch series, testing all combinations is fairly difficult. I've attempted to make sure that all combinations of CONFIG_ options are good, but it wouldn't surprise me if I missed something. I apologize in advance and I'll do my best to fix any problems that are found. I'll also note that the CC list is pretty giant. Some of this is based on get_maintainers and some of this is people I thought might be interested. Now that this series is touching so many files, I've stopped auto-CCing everyone that get_maintainers suggests. I'll reply to v3 and point at this patch to make sure folks are aware of it, but if I stopped CCing you and you want back on then please yell. As far as I can tell, there's no true MAINTAINER listed for the existing watchdog code. Assuming people don't hate this, maybe it would go through Andrew Morton's tree? There is now some arch-specific code for sparc and powerpc, but it's all still watchdog code so hopefully that would still be fine to go through the same tree. [1] https://lore.kernel.org/r/20230501082341.v3.1.I6bf789d21d0c3d75d382e7e51a804a7a51315f2c@changeid [2] https://lore.kernel.org/r/ZFEqynvf5nqkzEvQ@alley [3] https://lore.kernel.org/r/ZFErmshcrcikrSU1@alley [4] https://lore.kernel.org/linux-arm-kernel/20220903093415.15850-1-lecopzer.c...@mediatek.com/ [5] https://lore.kernel.org/r/20230419225604.21204-1-diand...@chromium.org Changes in v4: - ("Add a "cpu" param to watchdog_hardlockup_check()") new for v4. - ("Add a weak function for an arch to detect ...") new for v4. - ("Define dummy watchdog_update_hrtimer_threshold() ...") new for v4. - ("Have the perf hardlockup use __weak ...") new for v4. - ("Move perf hardlockup checking/panic ...") new for v4. - ("Move perf hardlockup watchdog petting to watchdog.c") new for v4. - ("Rename some "NMI watchdog" constants/function ...") new for v4. - ("Rename touch_nmi_watchdog() to ...") new for v4. - ("Rename watchdog_hld.c to watchdog_perf.c") new for v4. - ("Style changes to watchdog_hardlockup_check ...") new for v4. - Pulled ("Adapt the watchdog_hld interface ...") into my series for v4. - Pulled ("Enable perf events based hard ...") into my series for v4. - Pulled ("Ensure CPU-bound context when creating ...") into my series for v4. - Pulled ("add hw_nmi_get_sample_period for ...") into my series for v4. - Pulled ("change watchdog_nmi_enable() to void") into my series for v4. - Pulled ("remove WATCHDOG_DEFAULT") into my series for v4. - Reworked atop a whole pile of cleanups, as suggested by Petr. Changes in v3: - Added a note in commit message about the effect on idle. - Cleaned up commit message pros/cons to be complete sentences. - More cpu => CPU (in Kconfig and comments). - No code changes other than comments. Changes in v2: - No code changes. - Reworked description and Kconfig based on v1 discussion. - cpu => CPU (in commit message). Colin Cross (1): watchdog/hardlockup: detect hard lockups using secondary (buddy) CPUs Douglas Anderson (11): watchdog/perf: Define dummy watchdog_update_hrtimer_threshold() on correct config watchdog/hardlockup: Rename touch_nmi_watchdog() to touch_hardlockup_watchdog() watchdog/perf: Rename watchdog_hld.c to watchdog_perf.c watchdog/hardlockup: Move perf hardlockup checking/panic to common watchdog.c watchdog/hardlockup: Style changes to watchdog_hardlockup_check() / ..._is_lockedup() watchdog/hardlockup: Add a "cpu" param to watchdog_hardlockup_check() watchdog/hardlockup: Move perf hardlockup watchdog petting to watchdog.c watchdog/hardlockup: Rename some "NMI watchdog" constants/function watchdog/hardlockup: Have the perf hardlockup use __weak functions more cleanly watchdog/perf: Add a weak function for an arch to detect if perf can use NMIs arm64: Enable perf events based hard lockup detector Lecopzer Chen (4): watchdog: remove WATCHDOG_DEFAULT watchdog/hardlockup: change watchdog_nmi_enable() to void watchdog/perf: Adapt the watchdog_perf interface for async model arm64: add hw_nmi_get_sample_period for preparation of lockup detector Pingfan Liu (1): watchdog/perf: Ensure CPU-bound context when creating hardlockup detector event arch/arm64/Kconfig | 2 + arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/perf_event.c | 12 +- arch/arm64/kernel/watchdog_hld.c | 36 +++ arch/powerpc/include/asm/nmi.h | 4 +- arch/powerpc/kernel/watchdog.c | 12 +- arch/powerpc/platforms/pseries/mobility.c | 4 +- arch/sparc/kernel/nmi.c | 10 +- drivers/perf/arm_pmu.c | 5 + include/linux/nmi.h | 73 +++-- include/linux/perf/arm_pmu.h | 2 + kernel/Makefile | 3 +- kernel/watchdog.c | 293 ++++++++++++++++----- kernel/watchdog_buddy.c | 93 +++++++ kernel/{watchdog_hld.c => watchdog_perf.c} | 105 +++----- lib/Kconfig.debug | 52 +++- 16 files changed, 527 insertions(+), 180 deletions(-) create mode 100644 arch/arm64/kernel/watchdog_hld.c create mode 100644 kernel/watchdog_buddy.c rename kernel/{watchdog_hld.c => watchdog_perf.c} (72%) -- 2.40.1.521.gf1e218fcd8-goog
