Currently the memtest results were only presented in dmesg.
When running a large fleet of devices without ECC RAM it's currently not
easy to do bulk monitoring for memory corruption. You have to parse
dmesg, but that's a ring buffer so the error might disappear after some
time. In general I do not consider dmesg to be a great API to query RAM
status.
In several companies I've seen such errors remain undetected and cause
issues for way too long. So I think it makes sense to provide a
monitoring API, so that we can safely detect and act upon them.
This adds /proc/meminfo entry which can be easily used by scripts.
Link: https://lkml.kernel.org/r/20230321103430.7130-1-tomas.mudrunka@gmail.com
Signed-off-by: Tomas Mudrunka <tomas.mudrunka@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
VmallocUsed: 40444 kB
VmallocChunk: 0 kB
Percpu: 29312 kB
+ EarlyMemtestBad: 0 kB
HardwareCorrupted: 0 kB
AnonHugePages: 4149248 kB
ShmemHugePages: 0 kB
Percpu
Memory allocated to the percpu allocator used to back percpu
allocations. This stat excludes the cost of metadata.
+EarlyMemtestBad
+ The amount of RAM/memory in kB, that was identified as corrupted
+ by early memtest. If memtest was not run, this field will not
+ be displayed at all. Size is never rounded down to 0 kB.
+ That means if 0 kB is reported, you can safely assume
+ there was at least one pass of memtest and none of the passes
+ found a single faulty byte of RAM.
HardwareCorrupted
The amount of RAM/memory in KB, the kernel identifies as
corrupted.
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/mmzone.h>
+#include <linux/memblock.h>
#include <linux/proc_fs.h>
#include <linux/percpu.h>
#include <linux/seq_file.h>
show_val_kb(m, "VmallocChunk: ", 0ul);
show_val_kb(m, "Percpu: ", pcpu_nr_pages());
+#ifdef CONFIG_MEMTEST
+ if (early_memtest_done) {
+ unsigned long early_memtest_bad_size_kb;
+
+ early_memtest_bad_size_kb = early_memtest_bad_size>>10;
+ if (early_memtest_bad_size && !early_memtest_bad_size_kb)
+ early_memtest_bad_size_kb = 1;
+ /* When 0 is reported, it means there actually was a successful test */
+ seq_printf(m, "EarlyMemtestBad: %5lu kB\n", early_memtest_bad_size_kb);
+ }
+#endif
+
#ifdef CONFIG_MEMORY_FAILURE
seq_printf(m, "HardwareCorrupted: %5lu kB\n",
atomic_long_read(&num_poisoned_pages) << (PAGE_SHIFT - 10));
#endif
#ifdef CONFIG_MEMTEST
+extern phys_addr_t early_memtest_bad_size; /* Size of faulty ram found by memtest */
+extern bool early_memtest_done; /* Was early memtest done? */
extern void early_memtest(phys_addr_t start, phys_addr_t end);
#else
static inline void early_memtest(phys_addr_t start, phys_addr_t end)
#include <linux/init.h>
#include <linux/memblock.h>
+bool early_memtest_done;
+phys_addr_t early_memtest_bad_size;
+
static u64 patterns[] __initdata = {
/* The first entry has to be 0 to leave memtest with zeroed memory */
0,
pr_info(" %016llx bad mem addr %pa - %pa reserved\n",
cpu_to_be64(pattern), &start_bad, &end_bad);
memblock_reserve(start_bad, end_bad - start_bad);
+ early_memtest_bad_size += (end_bad - start_bad);
}
static void __init memtest(u64 pattern, phys_addr_t start_phys, phys_addr_t size)
}
if (start_bad)
reserve_bad_mem(pattern, start_bad, last_bad + incr);
+
+ early_memtest_done = true;
}
static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)