diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/vmstat.c | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index a7de9ad..c831be3 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1379,6 +1379,66 @@ static DEFINE_PER_CPU(struct delayed_work, vmstat_work); int sysctl_stat_interval __read_mostly = HZ; static cpumask_var_t cpu_stat_off; +#ifdef CONFIG_PROC_FS +static void refresh_vm_stats(struct work_struct *work) +{ + refresh_cpu_vm_stats(true); +} + +int vmstat_refresh(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + long val; + int err; + int i; + + /* + * The regular update, every sysctl_stat_interval, may come later + * than expected: leaving a significant amount in per_cpu buckets. + * This is particularly misleading when checking a quantity of HUGE + * pages, immediately after running a test. /proc/sys/vm/stat_refresh, + * which can equally be echo'ed to or cat'ted from (by root), + * can be used to update the stats just before reading them. + * + * Oh, and since global_page_state() etc. are so careful to hide + * transiently negative values, report an error here if any of + * the stats is negative, so we know to go looking for imbalance. + */ + err = schedule_on_each_cpu(refresh_vm_stats); + if (err) + return err; + for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) { + val = atomic_long_read(&vm_stat[i]); + if (val < 0) { + switch (i) { + case NR_ALLOC_BATCH: + case NR_PAGES_SCANNED: + /* + * These are often seen to go negative in + * recent kernels, but not to go permanently + * negative. Whilst it would be nicer not to + * have exceptions, rooting them out would be + * another task, of rather low priority. + */ + break; + default: + pr_warn("%s: %s %ld\n", + __func__, vmstat_text[i], val); + err = -EINVAL; + break; + } + } + } + if (err) + return err; + if (write) + *ppos += *lenp; + else + *lenp = 0; + return 0; +} +#endif /* CONFIG_PROC_FS */ + static void vmstat_update(struct work_struct *w) { if (refresh_cpu_vm_stats(true)) { |
