mm/slub: add taint after the errors are printed

When running the kernel with panic_on_taint, the usual slub debug error
messages are not being printed when object corruption happens.  That's
because we panic in add_taint(), which is called before printing the
additional information.  This is a bit unfortunate as the error messages
are actually very useful, especially before a panic.  Let's fix this by
moving add_taint() after the errors are printed on the console.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Georgi Djakov <[email protected]>
Acked-by: Rafael Aquini <[email protected]>
Acked-by: David Rientjes <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Reviewed-by: Aaron Tomlin <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/slub.c

@@ -708,8 +708,6 @@ static void slab_bug(struct kmem_cache *s, char *fmt, ...)
 	pr_err("=============================================================================\n");
 	pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf);
 	pr_err("-----------------------------------------------------------------------------\n\n");
-
-	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 	va_end(args);
 }
 
@@ -790,6 +788,7 @@ void object_err(struct kmem_cache *s, struct page *page,
 
 	slab_bug(s, "%s", reason);
 	print_trailer(s, page, object);
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 }
 
 static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page,
@@ -807,6 +806,7 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page,
 	slab_bug(s, "%s", buf);
 	print_page_info(page);
 	dump_stack();
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 }
 
 static void init_object(struct kmem_cache *s, void *object, u8 val)
@@ -858,6 +858,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
 					fault, end - 1, fault - addr,
 					fault[0], value);
 	print_trailer(s, page, object);
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 
 skip_bug_print:
 	restore_bytes(s, what, value, fault, end);