cec.c (9632a3299bb1897f01c6a485ff035b20e61d7ae1) cec.c (b8b5ca6600dec2a4f1e50ca9d3cf9e1d032870cd)
1// SPDX-License-Identifier: GPL-2.0
2#include <linux/mm.h>
3#include <linux/gfp.h>
4#include <linux/kernel.h>
5#include <linux/workqueue.h>
6
7#include <asm/mce.h>
8

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32 *
33 * Spring cleaning is what we do when we reach a certain number CLEAN_ELEMS of
34 * elements entered into the array, during which, we're decaying all elements.
35 * If, after decay, an element gets inserted again, its generation is set to 11b
36 * to make sure it has higher numerical count than other, older elements and
37 * thus emulate an an LRU-like behavior when deleting elements to free up space
38 * in the page.
39 *
1// SPDX-License-Identifier: GPL-2.0
2#include <linux/mm.h>
3#include <linux/gfp.h>
4#include <linux/kernel.h>
5#include <linux/workqueue.h>
6
7#include <asm/mce.h>
8

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32 *
33 * Spring cleaning is what we do when we reach a certain number CLEAN_ELEMS of
34 * elements entered into the array, during which, we're decaying all elements.
35 * If, after decay, an element gets inserted again, its generation is set to 11b
36 * to make sure it has higher numerical count than other, older elements and
37 * thus emulate an an LRU-like behavior when deleting elements to free up space
38 * in the page.
39 *
40 * When an element reaches it's max count of count_threshold, we try to poison
41 * it by assuming that errors triggered count_threshold times in a single page
42 * are excessive and that page shouldn't be used anymore. count_threshold is
40 * When an element reaches it's max count of action_threshold, we try to poison
41 * it by assuming that errors triggered action_threshold times in a single page
42 * are excessive and that page shouldn't be used anymore. action_threshold is
43 * initialized to COUNT_MASK which is the maximum.
44 *
45 * That error event entry causes cec_add_elem() to return !0 value and thus
46 * signal to its callers to log the error.
47 *
48 * To the question why we've chosen a page and moving elements around with
49 * memmove(), it is because it is a very simple structure to handle and max data
50 * movement is 4K which on highly optimized modern CPUs is almost unnoticeable.

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117 __u32 flags;
118 };
119} ce_arr;
120
121static DEFINE_MUTEX(ce_mutex);
122static u64 dfs_pfn;
123
124/* Amount of errors after which we offline */
43 * initialized to COUNT_MASK which is the maximum.
44 *
45 * That error event entry causes cec_add_elem() to return !0 value and thus
46 * signal to its callers to log the error.
47 *
48 * To the question why we've chosen a page and moving elements around with
49 * memmove(), it is because it is a very simple structure to handle and max data
50 * movement is 4K which on highly optimized modern CPUs is almost unnoticeable.

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117 __u32 flags;
118 };
119} ce_arr;
120
121static DEFINE_MUTEX(ce_mutex);
122static u64 dfs_pfn;
123
124/* Amount of errors after which we offline */
125static unsigned int count_threshold = COUNT_MASK;
125static u64 action_threshold = COUNT_MASK;
126
127/* Each element "decays" each decay_interval which is 24hrs by default. */
128#define CEC_DECAY_DEFAULT_INTERVAL 24 * 60 * 60 /* 24 hrs */
129#define CEC_DECAY_MIN_INTERVAL 1 * 60 * 60 /* 1h */
130#define CEC_DECAY_MAX_INTERVAL 30 * 24 * 60 * 60 /* one month */
131static struct delayed_work cec_work;
132static u64 decay_interval = CEC_DECAY_DEFAULT_INTERVAL;
133

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340 }
341
342 /* Add/refresh element generation and increment count */
343 ca->array[to] |= DECAY_MASK << COUNT_BITS;
344 ca->array[to]++;
345
346 /* Check action threshold and soft-offline, if reached. */
347 count = COUNT(ca->array[to]);
126
127/* Each element "decays" each decay_interval which is 24hrs by default. */
128#define CEC_DECAY_DEFAULT_INTERVAL 24 * 60 * 60 /* 24 hrs */
129#define CEC_DECAY_MIN_INTERVAL 1 * 60 * 60 /* 1h */
130#define CEC_DECAY_MAX_INTERVAL 30 * 24 * 60 * 60 /* one month */
131static struct delayed_work cec_work;
132static u64 decay_interval = CEC_DECAY_DEFAULT_INTERVAL;
133

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340 }
341
342 /* Add/refresh element generation and increment count */
343 ca->array[to] |= DECAY_MASK << COUNT_BITS;
344 ca->array[to]++;
345
346 /* Check action threshold and soft-offline, if reached. */
347 count = COUNT(ca->array[to]);
348 if (count >= count_threshold) {
348 if (count >= action_threshold) {
349 u64 pfn = ca->array[to] >> PAGE_SHIFT;
350
351 if (!pfn_valid(pfn)) {
352 pr_warn("CEC: Invalid pfn: 0x%llx\n", pfn);
353 } else {
354 /* We have reached max count for this page, soft-offline it. */
355 pr_err("Soft-offlining pfn: 0x%llx\n", pfn);
356 memory_failure_queue(pfn, MF_SOFT_OFFLINE);

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411 decay_interval = val;
412
413 cec_mod_work(decay_interval);
414
415 return 0;
416}
417DEFINE_DEBUGFS_ATTRIBUTE(decay_interval_ops, u64_get, decay_interval_set, "%lld\n");
418
349 u64 pfn = ca->array[to] >> PAGE_SHIFT;
350
351 if (!pfn_valid(pfn)) {
352 pr_warn("CEC: Invalid pfn: 0x%llx\n", pfn);
353 } else {
354 /* We have reached max count for this page, soft-offline it. */
355 pr_err("Soft-offlining pfn: 0x%llx\n", pfn);
356 memory_failure_queue(pfn, MF_SOFT_OFFLINE);

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411 decay_interval = val;
412
413 cec_mod_work(decay_interval);
414
415 return 0;
416}
417DEFINE_DEBUGFS_ATTRIBUTE(decay_interval_ops, u64_get, decay_interval_set, "%lld\n");
418
419static int count_threshold_set(void *data, u64 val)
419static int action_threshold_set(void *data, u64 val)
420{
421 *(u64 *)data = val;
422
423 if (val > COUNT_MASK)
424 val = COUNT_MASK;
425
420{
421 *(u64 *)data = val;
422
423 if (val > COUNT_MASK)
424 val = COUNT_MASK;
425
426 count_threshold = val;
426 action_threshold = val;
427
428 return 0;
429}
427
428 return 0;
429}
430DEFINE_DEBUGFS_ATTRIBUTE(count_threshold_ops, u64_get, count_threshold_set, "%lld\n");
430DEFINE_DEBUGFS_ATTRIBUTE(action_threshold_ops, u64_get, action_threshold_set, "%lld\n");
431
432static int array_dump(struct seq_file *m, void *v)
433{
434 struct ce_array *ca = &ce_arr;
435 int i;
436
437 mutex_lock(&ce_mutex);
438

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448 seq_printf(m, "Stats:\nCEs: %llu\nofflined pages: %llu\n",
449 ca->ces_entered, ca->pfns_poisoned);
450
451 seq_printf(m, "Flags: 0x%x\n", ca->flags);
452
453 seq_printf(m, "Decay interval: %lld seconds\n", decay_interval);
454 seq_printf(m, "Decays: %lld\n", ca->decays_done);
455
431
432static int array_dump(struct seq_file *m, void *v)
433{
434 struct ce_array *ca = &ce_arr;
435 int i;
436
437 mutex_lock(&ce_mutex);
438

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448 seq_printf(m, "Stats:\nCEs: %llu\nofflined pages: %llu\n",
449 ca->ces_entered, ca->pfns_poisoned);
450
451 seq_printf(m, "Flags: 0x%x\n", ca->flags);
452
453 seq_printf(m, "Decay interval: %lld seconds\n", decay_interval);
454 seq_printf(m, "Decays: %lld\n", ca->decays_done);
455
456 seq_printf(m, "Action threshold: %d\n", count_threshold);
456 seq_printf(m, "Action threshold: %lld\n", action_threshold);
457
458 mutex_unlock(&ce_mutex);
459
460 return 0;
461}
462
463static int array_open(struct inode *inode, struct file *filp)
464{

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497
498 decay = debugfs_create_file("decay_interval", S_IRUSR | S_IWUSR, d,
499 &decay_interval, &decay_interval_ops);
500 if (!decay) {
501 pr_warn("Error creating decay_interval debugfs node!\n");
502 goto err;
503 }
504
457
458 mutex_unlock(&ce_mutex);
459
460 return 0;
461}
462
463static int array_open(struct inode *inode, struct file *filp)
464{

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497
498 decay = debugfs_create_file("decay_interval", S_IRUSR | S_IWUSR, d,
499 &decay_interval, &decay_interval_ops);
500 if (!decay) {
501 pr_warn("Error creating decay_interval debugfs node!\n");
502 goto err;
503 }
504
505 count = debugfs_create_file("count_threshold", S_IRUSR | S_IWUSR, d,
506 &count_threshold, &count_threshold_ops);
505 count = debugfs_create_file("action_threshold", S_IRUSR | S_IWUSR, d,
506 &action_threshold, &action_threshold_ops);
507 if (!count) {
507 if (!count) {
508 pr_warn("Error creating count_threshold debugfs node!\n");
508 pr_warn("Error creating action_threshold debugfs node!\n");
509 goto err;
510 }
511
512
513 return 0;
514
515err:
516 debugfs_remove_recursive(d);

--- 41 unchanged lines hidden --- 		509 goto err;
510 }
511
512
513 return 0;
514
515err:
516 debugfs_remove_recursive(d);

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