diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-memory | 8 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-system-cpu | 8 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/memory-hotplug.rst | 8 | ||||
| -rw-r--r-- | Documentation/core-api/cpu_hotplug.rst | 18 | ||||
| -rw-r--r-- | drivers/base/cpu.c | 13 | ||||
| -rw-r--r-- | drivers/base/memory.c | 13 | ||||
| -rw-r--r-- | include/linux/kexec.h | 8 |
7 files changed, 76 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory index d8b0f80b9e33..a95e0f17c35a 100644 --- a/Documentation/ABI/testing/sysfs-devices-memory +++ b/Documentation/ABI/testing/sysfs-devices-memory @@ -110,3 +110,11 @@ Description: link is created for memory section 9 on node0. /sys/devices/system/node/node0/memory9 -> ../../memory/memory9 + +What: /sys/devices/system/memory/crash_hotplug +Date: Aug 2023 +Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> +Description: + (RO) indicates whether or not the kernel directly supports + modifying the crash elfcorehdr for memory hot un/plug and/or + on/offline changes. diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index ecd585ca2d50..31189da7ef57 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -686,3 +686,11 @@ Description: (RO) the list of CPUs that are isolated and don't participate in load balancing. These CPUs are set by boot parameter "isolcpus=". + +What: /sys/devices/system/cpu/crash_hotplug +Date: Aug 2023 +Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> +Description: + (RO) indicates whether or not the kernel directly supports + modifying the crash elfcorehdr for CPU hot un/plug and/or + on/offline changes. diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst index 1b02fe5807cc..eb99d79223a3 100644 --- a/Documentation/admin-guide/mm/memory-hotplug.rst +++ b/Documentation/admin-guide/mm/memory-hotplug.rst @@ -291,6 +291,14 @@ The following files are currently defined: Availability depends on the CONFIG_ARCH_MEMORY_PROBE kernel configuration option. ``uevent`` read-write: generic udev file for device subsystems. +``crash_hotplug`` read-only: when changes to the system memory map + occur due to hot un/plug of memory, this file contains + '1' if the kernel updates the kdump capture kernel memory + map itself (via elfcorehdr), or '0' if userspace must update + the kdump capture kernel memory map. + + Availability depends on the CONFIG_MEMORY_HOTPLUG kernel + configuration option. ====================== ========================================================= .. note:: diff --git a/Documentation/core-api/cpu_hotplug.rst b/Documentation/core-api/cpu_hotplug.rst index e6f5bc39cf5c..d6d470d7dda0 100644 --- a/Documentation/core-api/cpu_hotplug.rst +++ b/Documentation/core-api/cpu_hotplug.rst @@ -741,6 +741,24 @@ will receive all events. A script like:: can process the event further. +When changes to the CPUs in the system occur, the sysfs file +/sys/devices/system/cpu/crash_hotplug contains '1' if the kernel +updates the kdump capture kernel list of CPUs itself (via elfcorehdr), +or '0' if userspace must update the kdump capture kernel list of CPUs. + +The availability depends on the CONFIG_HOTPLUG_CPU kernel configuration +option. + +To skip userspace processing of CPU hot un/plug events for kdump +(i.e. the unload-then-reload to obtain a current list of CPUs), this sysfs +file can be used in a udev rule as follows: + + SUBSYSTEM=="cpu", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end" + +For a CPU hot un/plug event, if the architecture supports kernel updates +of the elfcorehdr (which contains the list of CPUs), then the rule skips +the unload-then-reload of the kdump capture kernel. + Kernel Inline Documentations Reference ====================================== diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index c1815b9dae68..c9204d69e616 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -282,6 +282,16 @@ static ssize_t print_cpus_nohz_full(struct device *dev, static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL); #endif +#ifdef CONFIG_CRASH_HOTPLUG +static ssize_t crash_hotplug_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + return sysfs_emit(buf, "%d\n", crash_hotplug_cpu_support()); +} +static DEVICE_ATTR_ADMIN_RO(crash_hotplug); +#endif + static void cpu_device_release(struct device *dev) { /* @@ -469,6 +479,9 @@ static struct attribute *cpu_root_attrs[] = { #ifdef CONFIG_NO_HZ_FULL &dev_attr_nohz_full.attr, #endif +#ifdef CONFIG_CRASH_HOTPLUG + &dev_attr_crash_hotplug.attr, +#endif #ifdef CONFIG_GENERIC_CPU_AUTOPROBE &dev_attr_modalias.attr, #endif diff --git a/drivers/base/memory.c b/drivers/base/memory.c index b456ac213610..15bb416e58ce 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -490,6 +490,16 @@ static ssize_t auto_online_blocks_store(struct device *dev, static DEVICE_ATTR_RW(auto_online_blocks); +#ifdef CONFIG_CRASH_HOTPLUG +#include <linux/kexec.h> +static ssize_t crash_hotplug_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%d\n", crash_hotplug_memory_support()); +} +static DEVICE_ATTR_RO(crash_hotplug); +#endif + /* * Some architectures will have custom drivers to do this, and * will not need to do it from userspace. The fake hot-add code @@ -889,6 +899,9 @@ static struct attribute *memory_root_attrs[] = { &dev_attr_block_size_bytes.attr, &dev_attr_auto_online_blocks.attr, +#ifdef CONFIG_CRASH_HOTPLUG + &dev_attr_crash_hotplug.attr, +#endif NULL }; diff --git a/include/linux/kexec.h b/include/linux/kexec.h index df395f888915..172e9a544928 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -486,6 +486,14 @@ static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) { static inline void arch_crash_handle_hotplug_event(struct kimage *image) { } #endif +#ifndef crash_hotplug_cpu_support +static inline int crash_hotplug_cpu_support(void) { return 0; } +#endif + +#ifndef crash_hotplug_memory_support +static inline int crash_hotplug_memory_support(void) { return 0; } +#endif + #else /* !CONFIG_KEXEC_CORE */ struct pt_regs; struct task_struct; |