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-rw-r--r--mm/memory-failure.c68
1 files changed, 68 insertions, 0 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5055b940df5f..ed6e91c87a54 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);