Merge tag 'netfs-lib-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowe...

[sfrench/cifs-2.6.git] / mm / internal.h

diff --git a/mm/internal.h b/mm/internal.h
index 83a07b2a7b1f701677b1ea9dca56da8bbaaa96dd..bbe900f9f095ac58b5c4661a5ae26602f48a3497 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -96,6 +96,26 @@ static inline void set_page_refcounted(struct page *page)
        set_page_count(page, 1);
 }
 
+/*
+ * When kernel touch the user page, the user page may be have been marked
+ * poison but still mapped in user space, if without this page, the kernel
+ * can guarantee the data integrity and operation success, the kernel is
+ * better to check the posion status and avoid touching it, be good not to
+ * panic, coredump for process fatal signal is a sample case matching this
+ * scenario. Or if kernel can't guarantee the data integrity, it's better
+ * not to call this function, let kernel touch the poison page and get to
+ * panic.
+ */
+static inline bool is_page_poisoned(struct page *page)
+{
+       if (PageHWPoison(page))
+               return true;
+       else if (PageHuge(page) && PageHWPoison(compound_head(page)))
+               return true;
+
+       return false;
+}
+
 extern unsigned long highest_memmap_pfn;
 
 /*