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// SPDX-License-Identifier: GPL-2.0-only
/* 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 <linux/page-flags.h>
#include <linux/memcontrol.h>
#include "internal.h"
static u32 hwpoison_filter_enable;
static u32 hwpoison_filter_dev_major = ~0U;
static u32 hwpoison_filter_dev_minor = ~0U;
static u64 hwpoison_filter_flags_mask;
static u64 hwpoison_filter_flags_value;
static int hwpoison_filter_dev(struct page *p)
{
struct folio *folio = page_folio(p);
struct address_space *mapping;
dev_t dev;
if (hwpoison_filter_dev_major == ~0U &&
hwpoison_filter_dev_minor == ~0U)
return 0;
mapping = folio_mapping(folio);
if (mapping == NULL || mapping->host == NULL)
return -EINVAL;
dev = mapping->host->i_sb->s_dev;
if (hwpoison_filter_dev_major != ~0U &&
hwpoison_filter_dev_major != MAJOR(dev))
return -EINVAL;
if (hwpoison_filter_dev_minor != ~0U &&
hwpoison_filter_dev_minor != MINOR(dev))
return -EINVAL;
return 0;
}
static int hwpoison_filter_flags(struct page *p)
{
if (!hwpoison_filter_flags_mask)
return 0;
if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
hwpoison_filter_flags_value)
return 0;
else
return -EINVAL;
}
/*
* This allows stress tests to limit test scope to a collection of tasks
* by putting them under some memcg. This prevents killing unrelated/important
* processes such as /sbin/init. Note that the target task may share clean
* pages with init (eg. libc text), which is harmless. If the target task
* share _dirty_ pages with another task B, the test scheme must make sure B
* is also included in the memcg. At last, due to race conditions this filter
* can only guarantee that the page either belongs to the memcg tasks, or is
* a freed page.
*/
#ifdef CONFIG_MEMCG
static u64 hwpoison_filter_memcg;
static int hwpoison_filter_task(struct page *p)
{
if (!hwpoison_filter_memcg)
return 0;
if (page_cgroup_ino(p) != hwpoison_filter_memcg)
return -EINVAL;
return 0;
}
#else
static int hwpoison_filter_task(struct page *p) { return 0; }
#endif
static int hwpoison_filter(struct page *p)
{
if (!hwpoison_filter_enable)
return 0;
if (hwpoison_filter_dev(p))
return -EINVAL;
if (hwpoison_filter_flags(p))
return -EINVAL;
if (hwpoison_filter_task(p))
return -EINVAL;
return 0;
}
static struct dentry *hwpoison_dir;
static int hwpoison_inject(void *data, u64 val)
{
unsigned long pfn = val;
struct page *p;
struct folio *folio;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (!pfn_valid(pfn))
return -ENXIO;
p = pfn_to_page(pfn);
folio = page_folio(p);
if (!hwpoison_filter_enable)
goto inject;
shake_folio(folio);
/*
* This implies unable to support non-LRU pages except free page.
*/
if (!folio_test_lru(folio) && !folio_test_hugetlb(folio) &&
!is_free_buddy_page(p))
return 0;
/*
* do a racy check to make sure PG_hwpoison will only be set for
* the targeted owner (or on a free page).
* memory_failure() will redo the check reliably inside page lock.
*/
err = hwpoison_filter(&folio->page);
if (err)
return 0;
inject:
pr_info("Injecting memory failure at pfn %#lx\n", pfn);
err = memory_failure(pfn, MF_SW_SIMULATED);
return (err == -EOPNOTSUPP) ? 0 : err;
}
static int hwpoison_unpoison(void *data, u64 val)
{
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
return unpoison_memory(val);
}
DEFINE_DEBUGFS_ATTRIBUTE(hwpoison_fops, NULL, hwpoison_inject, "%lli\n");
DEFINE_DEBUGFS_ATTRIBUTE(unpoison_fops, NULL, hwpoison_unpoison, "%lli\n");
static void __exit pfn_inject_exit(void)
{
hwpoison_filter_enable = 0;
hwpoison_filter_unregister();
debugfs_remove_recursive(hwpoison_dir);
}
static int __init pfn_inject_init(void)
{
hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
/*
* 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.
*/
debugfs_create_file("corrupt-pfn", 0200, hwpoison_dir, NULL,
&hwpoison_fops);
debugfs_create_file("unpoison-pfn", 0200, hwpoison_dir, NULL,
&unpoison_fops);
debugfs_create_u32("corrupt-filter-enable", 0600, hwpoison_dir,
&hwpoison_filter_enable);
debugfs_create_u32("corrupt-filter-dev-major", 0600, hwpoison_dir,
&hwpoison_filter_dev_major);
debugfs_create_u32("corrupt-filter-dev-minor", 0600, hwpoison_dir,
&hwpoison_filter_dev_minor);
debugfs_create_u64("corrupt-filter-flags-mask", 0600, hwpoison_dir,
&hwpoison_filter_flags_mask);
debugfs_create_u64("corrupt-filter-flags-value", 0600, hwpoison_dir,
&hwpoison_filter_flags_value);
#ifdef CONFIG_MEMCG
debugfs_create_u64("corrupt-filter-memcg", 0600, hwpoison_dir,
&hwpoison_filter_memcg);
#endif
hwpoison_filter_register(hwpoison_filter);
return 0;
}
module_init(pfn_inject_init);
module_exit(pfn_inject_exit);
MODULE_DESCRIPTION("HWPoison pages injector");
MODULE_LICENSE("GPL");
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