mm/swap: print bad swap offset entry in get_swap_device

If offset exceeds the si->max, print bad swap offset entry to help debug
the unexpected case.

Link: https://lkml.kernel.org/r/20220509131416.17553-6-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 570287b786cc86d1e61591c0cd129c35a20d33e6..f59abca5cea97ea5b90959402d4311e25c476802 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1271,6 +1271,7 @@ bad_nofile:
 out:
        return NULL;
 put_out:
+       pr_err("%s: %s%08lx\n", __func__, Bad_offset, entry.val);
        percpu_ref_put(&si->users);
        return NULL;
 }