mm: fix madivse_pageout mishandling on non-LRU page

MADV_PAGEOUT tries to isolate non-LRU pages and get the warning from isolate_lru_page below.
Fix it with checking PageLRU in advance.

------------[ cut here ]------------
trying to isolate tail page
WARNING: CPU: 0 PID: 6175 at mm/folio-compat.c:158 isolate_lru_page+0x130/0x140
Modules linked in:
CPU: 0 PID: 6175 Comm: syz-executor.0 Not tainted 5.18.12 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:isolate_lru_page+0x130/0x140

---
 mm/madvise.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

index 682e1d161aef..a3fc4cd32ed3 100644
@@ -452,8 +452,11 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 			continue;
 		}
 
-		/* Do not interfere with other mappings of this page */
-		if (page_mapcount(page) != 1)
+		/*
+		 * Do not interfere with other mappings of this page and
+		 * non-LRU page.
+		 */
+		if (!PageLRU(page) || page_mapcount(page) != 1)
 			continue;
 
 		VM_BUG_ON_PAGE(PageTransCompound(page), page);

2.37.2.672.g94769d06f0-goog