"/sys/kernel/kexec_crash_size" only handles crashk_res, it is fine in most cases, but sometimes we have crashk_low_res. For example, when "crashkernel=size[KMG],high" combined with "crashkernel=size[KMG],low" is used for 64-bit x86.
Like crashk_res, we introduce the corresponding sysfs file "/sys/kernel/kexec_crash_low_size" for crashk_low_res. So, the exact total reserved memory is the sum of the two. crashk_low_res can also be shrunk via this new interface, and users should be aware of what they are doing. Suggested-by: Dave Young <[email protected]> Signed-off-by: Xunlei Pang <[email protected]> --- include/linux/kexec.h | 4 ++-- kernel/kexec_core.c | 23 ++++++++++++----------- kernel/ksysfs.c | 25 +++++++++++++++++++++++-- 3 files changed, 37 insertions(+), 15 deletions(-) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index d743777..4f271fc 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -304,8 +304,8 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram, unsigned long long *crash_size, unsigned long long *crash_base); int parse_crashkernel_low(char *cmdline, unsigned long long system_ram, unsigned long long *crash_size, unsigned long long *crash_base); -int crash_shrink_memory(unsigned long new_size); -size_t crash_get_memory_size(void); +int crash_shrink_memory(struct resource *res, unsigned long new_size); +size_t crash_get_memory_size(struct resource *res); void crash_free_reserved_phys_range(unsigned long begin, unsigned long end); int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf, diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 5616755..707d18e 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -925,13 +925,13 @@ void crash_kexec(struct pt_regs *regs) } } -size_t crash_get_memory_size(void) +size_t crash_get_memory_size(struct resource *res) { size_t size = 0; mutex_lock(&kexec_mutex); - if (crashk_res.end != crashk_res.start) - size = resource_size(&crashk_res); + if (res->end != res->start) + size = resource_size(res); mutex_unlock(&kexec_mutex); return size; } @@ -945,7 +945,7 @@ void __weak crash_free_reserved_phys_range(unsigned long begin, free_reserved_page(boot_pfn_to_page(addr >> PAGE_SHIFT)); } -int crash_shrink_memory(unsigned long new_size) +int crash_shrink_memory(struct resource *res, unsigned long new_size) { int ret = 0; unsigned long start, end; @@ -958,8 +958,9 @@ int crash_shrink_memory(unsigned long new_size) ret = -ENOENT; goto unlock; } - start = crashk_res.start; - end = crashk_res.end; + + start = res->start; + end = res->end; old_size = (end == 0) ? 0 : end - start + 1; if (new_size >= old_size) { ret = (new_size == old_size) ? 0 : -EINVAL; @@ -975,17 +976,17 @@ int crash_shrink_memory(unsigned long new_size) start = roundup(start, KEXEC_CRASH_MEM_ALIGN); end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN); - crash_free_reserved_phys_range(end, crashk_res.end); + crash_free_reserved_phys_range(end, res->end); - if ((start == end) && (crashk_res.parent != NULL)) - release_resource(&crashk_res); + if ((start == end) && (res->parent != NULL)) + release_resource(res); ram_res->start = end; - ram_res->end = crashk_res.end; + ram_res->end = res->end; ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM; ram_res->name = "System RAM"; - crashk_res.end = end - 1; + res->end = end - 1; insert_resource(&iomem_resource, ram_res); diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index ee1bc1b..3336fd5 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -105,10 +105,30 @@ static ssize_t kexec_crash_loaded_show(struct kobject *kobj, } KERNEL_ATTR_RO(kexec_crash_loaded); +static ssize_t kexec_crash_low_size_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%zu\n", crash_get_memory_size(&crashk_low_res)); +} +static ssize_t kexec_crash_low_size_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + unsigned long cnt; + int ret; + + if (kstrtoul(buf, 0, &cnt)) + return -EINVAL; + + ret = crash_shrink_memory(&crashk_low_res, cnt); + return ret < 0 ? ret : count; +} +KERNEL_ATTR_RW(kexec_crash_low_size); + static ssize_t kexec_crash_size_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { - return sprintf(buf, "%zu\n", crash_get_memory_size()); + return sprintf(buf, "%zu\n", crash_get_memory_size(&crashk_res)); } static ssize_t kexec_crash_size_store(struct kobject *kobj, struct kobj_attribute *attr, @@ -120,7 +140,7 @@ static ssize_t kexec_crash_size_store(struct kobject *kobj, if (kstrtoul(buf, 0, &cnt)) return -EINVAL; - ret = crash_shrink_memory(cnt); + ret = crash_shrink_memory(&crashk_res, cnt); return ret < 0 ? ret : count; } KERNEL_ATTR_RW(kexec_crash_size); @@ -218,6 +238,7 @@ static struct attribute * kernel_attrs[] = { #ifdef CONFIG_KEXEC_CORE &kexec_loaded_attr.attr, &kexec_crash_loaded_attr.attr, + &kexec_crash_low_size_attr.attr, &kexec_crash_size_attr.attr, &vmcoreinfo_attr.attr, #endif -- 1.8.3.1
