mm: Remove bogus VM_BUG_ON

It is not safe to check page->index without holding the page lock.
It can be changed if the page is moved between the swap cache and the
page cache for a shmem file, for example.  There is a VM_BUG_ON below
which checks page->index is correct after taking the page lock.

Cc: stable@vger.kernel.org
Fixes: 5c211ba29deb ("mm: add and use find_lock_entries")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index dae481293b5d95742bf440351d0a79e5f95e9384..82a17c35eb96bcd4155d783f544a52a70269b1a7 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2093,7 +2093,6 @@ unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
                if (!xa_is_value(page)) {
                        if (page->index < start)
                                goto put;
-                       VM_BUG_ON_PAGE(page->index != xas.xa_index, page);
                        if (page->index + thp_nr_pages(page) - 1 > end)
                                goto put;
                        if (!trylock_page(page))