hwpoison-inject.c

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/* Inject a hwpoison memory failure on a arbitrary pfn */
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/hugetlb.h>
#include "internal.h"

static struct dentry *hwpoison_dir;

static int hwpoison_inject(void *data, u64 val)
{
    unsigned long pfn = val;
    struct page *p;
    struct page *hpage;
    int err;

    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;

    if (!hwpoison_filter_enable)
        goto inject;
    if (!pfn_valid(pfn))
        return -ENXIO;

    p = pfn_to_page(pfn);
    hpage = compound_head(p);
    /*
     * This implies unable to support free buddy pages.
     */
    if (!get_page_unless_zero(hpage))
        return 0;

    if (!PageLRU(p) && !PageHuge(p))
        shake_page(p, 0);
    /*
     * This implies unable to support non-LRU pages.
     */
    if (!PageLRU(p) && !PageHuge(p))
        return 0;

    /*
     * do a racy check with elevated page count, to make sure PG_hwpoison
     * will only be set for the targeted owner (or on a free page).
     * We temporarily take page lock for try_get_mem_cgroup_from_page().
     * memory_failure() will redo the check reliably inside page lock.
     */
    lock_page(hpage);
    err = hwpoison_filter(hpage);
    unlock_page(hpage);
    if (err)
        return 0;

inject:
    printk(KERN_INFO "Injecting memory failure at pfn %lx\n", pfn);
    return memory_failure(pfn, 18, MF_COUNT_INCREASED);
}

static int hwpoison_unpoison(void *data, u64 val)
{
    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;

    return unpoison_memory(val);
}

DEFINE_SIMPLE_ATTRIBUTE(hwpoison_fops, NULL, hwpoison_inject, "%lli\n");
DEFINE_SIMPLE_ATTRIBUTE(unpoison_fops, NULL, hwpoison_unpoison, "%lli\n");

static void pfn_inject_exit(void)
{
    if (hwpoison_dir)
        debugfs_remove_recursive(hwpoison_dir);
}

static int pfn_inject_init(void)
{
    struct dentry *dentry;

    hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
    if (hwpoison_dir == NULL)
        return -ENOMEM;

    /*
     * Note that the below poison/unpoison interfaces do not involve
     * hardware status change, hence do not require hardware support.
     * They are mainly for testing hwpoison in software level.
     */
    dentry = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
                      NULL, &hwpoison_fops);
    if (!dentry)
        goto fail;

    dentry = debugfs_create_file("unpoison-pfn", 0600, hwpoison_dir,
                     NULL, &unpoison_fops);
    if (!dentry)
        goto fail;

    dentry = debugfs_create_u32("corrupt-filter-enable", 0600,
                    hwpoison_dir, &hwpoison_filter_enable);
    if (!dentry)
        goto fail;

    dentry = debugfs_create_u32("corrupt-filter-dev-major", 0600,
                    hwpoison_dir, &hwpoison_filter_dev_major);
    if (!dentry)
        goto fail;

    dentry = debugfs_create_u32("corrupt-filter-dev-minor", 0600,
                    hwpoison_dir, &hwpoison_filter_dev_minor);
    if (!dentry)
        goto fail;

    dentry = debugfs_create_u64("corrupt-filter-flags-mask", 0600,
                    hwpoison_dir, &hwpoison_filter_flags_mask);
    if (!dentry)
        goto fail;

    dentry = debugfs_create_u64("corrupt-filter-flags-value", 0600,
                    hwpoison_dir, &hwpoison_filter_flags_value);
    if (!dentry)
        goto fail;

#ifdef CONFIG_MEMCG_SWAP
    dentry = debugfs_create_u64("corrupt-filter-memcg", 0600,
                    hwpoison_dir, &hwpoison_filter_memcg);
    if (!dentry)
        goto fail;
#endif

    return 0;
fail:
    pfn_inject_exit();
    return -ENOMEM;
}

module_init(pfn_inject_init);
module_exit(pfn_inject_exit);
MODULE_LICENSE("GPL");