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Message-ID: <aXwQngYZx9Nk7hbv@fedora>
Date: Fri, 30 Jan 2026 09:59:58 +0800
From: Baoquan He <bhe@...hat.com>
To: Breno Leitao <leitao@...ian.org>
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
kernel-team@...a.com, kexec@...ts.infradead.org, dyoung@...hat.com,
tony.luck@...el.com, xueshuai@...ux.alibaba.com, vgoyal@...hat.com,
zhiquan1.li@...el.com, olja@...a.com
Subject: Re: [PATCH] vmcore_info: expose hardware error recovery statistics
via sysfs
On 01/29/26 at 05:34am, Breno Leitao wrote:
> Add a sysfs file at /sys/kernel/vmcore_stats and expose hardware error
> recovery statistics that are already tracked by the kernel. This allows
> userspace monitoring tools to track recovered hardware errors without
> requiring kernel crashes.
I don't understand. If w/o requring kernel crashes, why do you call it
vmcore_stats? It's a normal showing of hardware error recovery
statistics tracked by kernel, can we name it /sys/kernel/hwerr_stats?
It's obviously having nothiing to do with vmcore, isn't it?
>
> This is useful to track recoverable hardware errors in a time series,
> even if the host doesn't crash.
>
> Create a generic vmcore_stats sysfs, and add a section for
> hwerr_recovery that shows the counts per subsystem and timestamps:
>
> - cpu: CPU-related errors (MCE, ARM processor errors)
> - memory: Memory-related errors
> - pci: PCI/PCIe AER non-fatal errors
> - cxl: CXL errors
> - other: Other hardware errors
>
> Example output:
> hwerr_recovery:
> cpu: 0 (0)
> memory: 2 (1738148257)
> pci: 1 (1738147000)
> cxl: 0 (0)
> other: 0 (0)
>
> The value in parentheses is the timestamp (seconds since epoch) of the
> last error of that type, or 0 if no errors have occurred.
>
> These statistics provide visibility into the health of the system's
> hardware and can be used by system administrators to proactively detect
> failing components before they cause system crashes.
>
> Signed-off-by: Breno Leitao <leitao@...ian.org>
> ---
> To: akpm@...ux-foundation.org
> Cc: kexec@...ts.infradead.org
> To: bhe@...hat.com
> Cc: linux-kernel@...r.kernel.org
> Cc: dyoung@...hat.com
> Cc: tony.luck@...el.com
> Cc: xueshuai@...ux.alibaba.com
> Cc: vgoyal@...hat.com
> Cc: zhiquan1.li@...el.com
> Cc: olja@...a.com
> ---
> .../ABI/testing/sysfs-kernel-vmcore_stats | 23 ++++++++++++++++
> kernel/vmcore_info.c | 31 ++++++++++++++++++++++
> 2 files changed, 54 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-kernel-vmcore_stats b/Documentation/ABI/testing/sysfs-kernel-vmcore_stats
> new file mode 100644
> index 0000000000000..b42f18d24c00b
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-kernel-vmcore_stats
> @@ -0,0 +1,23 @@
> +What: /sys/kernel/vmcore_stats
> +Date: January 2026
> +KernelVersion: 6.20
> +Contact: Breno Leitao <leitao@...ian.org>
> +Description:
> + Shows statistics related to vmcore functionality. Currently
> + includes hardware error recovery statistics.
> +
> + Format:
> + Recovered hardware errors:
> + metric: count (timestamp)
> +
> + Statistics about recoverable hardware errors that the kernel
> + has handled since boot. Each metric shows the count and
> + timestamp (seconds since epoch) of the last error in
> + parentheses (0 if no errors have occurred).
> +
> + Metrics:
> + - cpu: CPU-related errors (MCE, ARM processor errors)
> + - memory: Memory-related errors
> + - pci: PCI/PCIe AER non-fatal errors
> + - cxl: CXL (Compute Express Link) errors
> + - other: Other hardware errors
> diff --git a/kernel/vmcore_info.c b/kernel/vmcore_info.c
> index fe9bf8db1922e..5974b4be08cbc 100644
> --- a/kernel/vmcore_info.c
> +++ b/kernel/vmcore_info.c
> @@ -6,6 +6,8 @@
>
> #include <linux/buildid.h>
> #include <linux/init.h>
> +#include <linux/kobject.h>
> +#include <linux/sysfs.h>
> #include <linux/utsname.h>
> #include <linux/vmalloc.h>
> #include <linux/sizes.h>
> @@ -135,6 +137,31 @@ void hwerr_log_error_type(enum hwerr_error_type src)
> }
> EXPORT_SYMBOL_GPL(hwerr_log_error_type);
>
> +/* sysfs interface for hardware error recovery statistics */
> +static ssize_t vmcore_stats_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + return sysfs_emit(buf,
> + "Recovered hardware errors:\n"
> + " cpu: %d (%lld)\n"
> + " memory: %d (%lld)\n"
> + " pci: %d (%lld)\n"
> + " cxl: %d (%lld)\n"
> + " other: %d (%lld)\n",
> + atomic_read(&hwerr_data[HWERR_RECOV_CPU].count),
> + (long long)READ_ONCE(hwerr_data[HWERR_RECOV_CPU].timestamp),
> + atomic_read(&hwerr_data[HWERR_RECOV_MEMORY].count),
> + (long long)READ_ONCE(hwerr_data[HWERR_RECOV_MEMORY].timestamp),
> + atomic_read(&hwerr_data[HWERR_RECOV_PCI].count),
> + (long long)READ_ONCE(hwerr_data[HWERR_RECOV_PCI].timestamp),
> + atomic_read(&hwerr_data[HWERR_RECOV_CXL].count),
> + (long long)READ_ONCE(hwerr_data[HWERR_RECOV_CXL].timestamp),
> + atomic_read(&hwerr_data[HWERR_RECOV_OTHERS].count),
> + (long long)READ_ONCE(hwerr_data[HWERR_RECOV_OTHERS].timestamp));
> +}
> +
> +static struct kobj_attribute vmcore_stats_attr = __ATTR_RO(vmcore_stats);
> +
> static int __init crash_save_vmcoreinfo_init(void)
> {
> vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL);
> @@ -244,6 +271,10 @@ static int __init crash_save_vmcoreinfo_init(void)
> arch_crash_save_vmcoreinfo();
> update_vmcoreinfo_note();
>
> + /* Create /sys/kernel/vmcore_stats */
> + if (sysfs_create_file(kernel_kobj, &vmcore_stats_attr.attr))
> + pr_warn("Failed to create vmcore_stats sysfs file\n");
> +
> return 0;
> }
>
>
> ---
> base-commit: 8dfce8991b95d8625d0a1d2896e42f93b9d7f68d
> change-id: 20260129-vmcoreinfo_sysfs-ff4687979cd5
>
> Best regards,
> --
> Breno Leitao <leitao@...ian.org>
>
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