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-rw-r--r--Documentation/vm/hwpoison.txt16
-rw-r--r--include/linux/mm.h1
-rw-r--r--include/linux/page-flags.h2
-rw-r--r--mm/hwpoison-inject.c36
-rw-r--r--mm/memory-failure.c68
5 files changed, 114 insertions, 9 deletions
diff --git a/Documentation/vm/hwpoison.txt b/Documentation/vm/hwpoison.txt
index 3ffadf8da61..f047e75acb2 100644
--- a/Documentation/vm/hwpoison.txt
+++ b/Documentation/vm/hwpoison.txt
@@ -98,10 +98,22 @@ madvise(MADV_POISON, ....)
hwpoison-inject module through debugfs
- /sys/debug/hwpoison/corrupt-pfn
-Inject hwpoison fault at PFN echoed into this file
+/sys/debug/hwpoison/
+corrupt-pfn
+
+Inject hwpoison fault at PFN echoed into this file.
+
+unpoison-pfn
+
+Software-unpoison page at PFN echoed into this file. This
+way a page can be reused again.
+This only works for Linux injected failures, not for real
+memory failures.
+
+Note these injection interfaces are not stable and might change between
+kernel versions
Architecture specific MCE injector
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 135e19198cd..8cdb941fc7b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1336,6 +1336,7 @@ enum mf_flags {
};
extern void memory_failure(unsigned long pfn, int trapno);
extern int __memory_failure(unsigned long pfn, int trapno, int flags);
+extern int unpoison_memory(unsigned long pfn);
extern int sysctl_memory_failure_early_kill;
extern int sysctl_memory_failure_recovery;
extern void shake_page(struct page *p);
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 49e907bd067..f9df6308af9 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -275,7 +275,7 @@ PAGEFLAG_FALSE(Uncached)
#ifdef CONFIG_MEMORY_FAILURE
PAGEFLAG(HWPoison, hwpoison)
-TESTSETFLAG(HWPoison, hwpoison)
+TESTSCFLAG(HWPoison, hwpoison)
#define __PG_HWPOISON (1UL << PG_hwpoison)
#else
PAGEFLAG_FALSE(HWPoison)
diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index e1d85137f08..6e35e563bf5 100644
--- a/mm/hwpoison-inject.c
+++ b/mm/hwpoison-inject.c
@@ -4,7 +4,7 @@
#include <linux/kernel.h>
#include <linux/mm.h>
-static struct dentry *hwpoison_dir, *corrupt_pfn;
+static struct dentry *hwpoison_dir;
static int hwpoison_inject(void *data, u64 val)
{
@@ -14,7 +14,16 @@ static int hwpoison_inject(void *data, u64 val)
return __memory_failure(val, 18, 0);
}
+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)
{
@@ -24,16 +33,31 @@ static void pfn_inject_exit(void)
static int pfn_inject_init(void)
{
+ struct dentry *dentry;
+
hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
if (hwpoison_dir == NULL)
return -ENOMEM;
- corrupt_pfn = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
+
+ /*
+ * 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 (corrupt_pfn == NULL) {
- pfn_inject_exit();
- return -ENOMEM;
- }
+ if (!dentry)
+ goto fail;
+
+ dentry = debugfs_create_file("unpoison-pfn", 0600, hwpoison_dir,
+ NULL, &unpoison_fops);
+ if (!dentry)
+ goto fail;
+
return 0;
+fail:
+ pfn_inject_exit();
+ return -ENOMEM;
}
module_init(pfn_inject_init);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5055b940df5..ed6e91c87a5 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -838,6 +838,16 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
* and in many cases impossible, so we just avoid it here.
*/
lock_page_nosync(p);
+
+ /*
+ * unpoison always clear PG_hwpoison inside page lock
+ */
+ if (!PageHWPoison(p)) {
+ action_result(pfn, "unpoisoned", IGNORED);
+ res = 0;
+ goto out;
+ }
+
wait_on_page_writeback(p);
/*
@@ -893,3 +903,61 @@ void memory_failure(unsigned long pfn, int trapno)
{
__memory_failure(pfn, trapno, 0);
}
+
+/**
+ * unpoison_memory - Unpoison a previously poisoned page
+ * @pfn: Page number of the to be unpoisoned page
+ *
+ * Software-unpoison a page that has been poisoned by
+ * memory_failure() earlier.
+ *
+ * This is only done on the software-level, so it only works
+ * for linux injected failures, not real hardware failures
+ *
+ * Returns 0 for success, otherwise -errno.
+ */
+int unpoison_memory(unsigned long pfn)
+{
+ struct page *page;
+ struct page *p;
+ int freeit = 0;
+
+ if (!pfn_valid(pfn))
+ return -ENXIO;
+
+ p = pfn_to_page(pfn);
+ page = compound_head(p);
+
+ if (!PageHWPoison(p)) {
+ pr_debug("MCE: Page was already unpoisoned %#lx\n", pfn);
+ return 0;
+ }
+
+ if (!get_page_unless_zero(page)) {
+ if (TestClearPageHWPoison(p))
+ atomic_long_dec(&mce_bad_pages);
+ pr_debug("MCE: Software-unpoisoned free page %#lx\n", pfn);
+ return 0;
+ }
+
+ lock_page_nosync(page);
+ /*
+ * This test is racy because PG_hwpoison is set outside of page lock.
+ * That's acceptable because that won't trigger kernel panic. Instead,
+ * the PG_hwpoison page will be caught and isolated on the entrance to
+ * the free buddy page pool.
+ */
+ if (TestClearPageHWPoison(p)) {
+ pr_debug("MCE: Software-unpoisoned page %#lx\n", pfn);
+ atomic_long_dec(&mce_bad_pages);
+ freeit = 1;
+ }
+ unlock_page(page);
+
+ put_page(page);
+ if (freeit)
+ put_page(page);
+
+ return 0;
+}
+EXPORT_SYMBOL(unpoison_memory);