mm/memory-failure.c: remove obsolete comment in __soft_offline_page

Since commit add05cec ("mm: soft-offline: don't free target page in
successful page migration"), set_migratetype_isolate logic is removed.
Remove this obsolete comment.

Link: https://lkml.kernel.org/r/20220218090118.1105-8-linmiaohe@huawei.comSigned-off-by: NMiaohe Lin <linmiaohe@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/memory-failure.c

@@ -2167,10 +2167,6 @@ static int __soft_offline_page(struct page *page)
 		ret = invalidate_inode_page(page);
 	unlock_page(page);
 
-	/*
-	 * RED-PEN would be better to keep it isolated here, but we
-	 * would need to fix isolation locking first.
-	 */
 	if (ret) {
 		pr_info("soft_offline: %#lx: invalidated\n", pfn);
 		page_handle_poison(page, false, true);