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![Tony Luck](/assets/img/avatar_default.png)
Some high end Intel Xeon systems report uncorrectable memory errors as a recoverable machine check. Linux has included code for some time to process these and just signal the affected processes (or even recover completely if the error was in a read only page that can be replaced by reading from disk). But we have no recovery path for errors encountered during kernel code execution. Except for some very specific cases were are unlikely to ever be able to recover. Enter memory mirroring. Actually 3rd generation of memory mirroing. Gen1: All memory is mirrored Pro: No s/w enabling - h/w just gets good data from other side of the mirror Con: Halves effective memory capacity available to OS/applications Gen2: Partial memory mirror - just mirror memory begind some memory controllers Pro: Keep more of the capacity Con: Nightmare to enable. Have to choose between allocating from mirrored memory for safety vs. NUMA local memory for performance Gen3: Address range partial memory mirror - some mirror on each memory controller Pro: Can tune the amount of mirror and keep NUMA performance Con: I have to write memory management code to implement The current plan is just to use mirrored memory for kernel allocations. This has been broken into two phases: 1) This patch series - find the mirrored memory, use it for boot time allocations 2) Wade into mm/page_alloc.c and define a ZONE_MIRROR to pick up the unused mirrored memory from mm/memblock.c and only give it out to select kernel allocations (this is still being scoped because page_alloc.c is scary). This patch (of 3): Add extra "flags" to memblock to allow selection of memory based on attribute. No functional changes Signed-off-by: Tony Luck <tony.luck@intel.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Hanjun Guo <guohanjun@huawei.com> Cc: Xiexiuqi <xiexiuqi@huawei.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
119 lines
3 KiB
C
119 lines
3 KiB
C
#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/init.h>
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#include <linux/pfn.h>
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#include <linux/memblock.h>
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static u64 patterns[] __initdata = {
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/* The first entry has to be 0 to leave memtest with zeroed memory */
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0,
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0xffffffffffffffffULL,
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0x5555555555555555ULL,
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0xaaaaaaaaaaaaaaaaULL,
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0x1111111111111111ULL,
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0x2222222222222222ULL,
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0x4444444444444444ULL,
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0x8888888888888888ULL,
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0x3333333333333333ULL,
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0x6666666666666666ULL,
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0x9999999999999999ULL,
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0xccccccccccccccccULL,
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0x7777777777777777ULL,
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0xbbbbbbbbbbbbbbbbULL,
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0xddddddddddddddddULL,
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0xeeeeeeeeeeeeeeeeULL,
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0x7a6c7258554e494cULL, /* yeah ;-) */
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};
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static void __init reserve_bad_mem(u64 pattern, phys_addr_t start_bad, phys_addr_t end_bad)
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{
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printk(KERN_INFO " %016llx bad mem addr %010llx - %010llx reserved\n",
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(unsigned long long) pattern,
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(unsigned long long) start_bad,
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(unsigned long long) end_bad);
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memblock_reserve(start_bad, end_bad - start_bad);
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}
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static void __init memtest(u64 pattern, phys_addr_t start_phys, phys_addr_t size)
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{
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u64 *p, *start, *end;
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phys_addr_t start_bad, last_bad;
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phys_addr_t start_phys_aligned;
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const size_t incr = sizeof(pattern);
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start_phys_aligned = ALIGN(start_phys, incr);
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start = __va(start_phys_aligned);
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end = start + (size - (start_phys_aligned - start_phys)) / incr;
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start_bad = 0;
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last_bad = 0;
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for (p = start; p < end; p++)
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*p = pattern;
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for (p = start; p < end; p++, start_phys_aligned += incr) {
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if (*p == pattern)
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continue;
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if (start_phys_aligned == last_bad + incr) {
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last_bad += incr;
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continue;
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}
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if (start_bad)
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reserve_bad_mem(pattern, start_bad, last_bad + incr);
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start_bad = last_bad = start_phys_aligned;
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}
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if (start_bad)
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reserve_bad_mem(pattern, start_bad, last_bad + incr);
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}
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static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)
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{
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u64 i;
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phys_addr_t this_start, this_end;
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for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &this_start,
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&this_end, NULL) {
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this_start = clamp(this_start, start, end);
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this_end = clamp(this_end, start, end);
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if (this_start < this_end) {
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printk(KERN_INFO " %010llx - %010llx pattern %016llx\n",
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(unsigned long long)this_start,
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(unsigned long long)this_end,
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(unsigned long long)cpu_to_be64(pattern));
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memtest(pattern, this_start, this_end - this_start);
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}
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}
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}
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/* default is disabled */
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static int memtest_pattern __initdata;
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static int __init parse_memtest(char *arg)
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{
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if (arg)
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memtest_pattern = simple_strtoul(arg, NULL, 0);
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else
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memtest_pattern = ARRAY_SIZE(patterns);
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return 0;
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}
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early_param("memtest", parse_memtest);
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void __init early_memtest(phys_addr_t start, phys_addr_t end)
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{
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unsigned int i;
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unsigned int idx = 0;
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if (!memtest_pattern)
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return;
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printk(KERN_INFO "early_memtest: # of tests: %d\n", memtest_pattern);
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for (i = memtest_pattern-1; i < UINT_MAX; --i) {
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idx = i % ARRAY_SIZE(patterns);
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do_one_pass(patterns[idx], start, end);
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}
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}
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